diff --git a/cli/generate-applications-defaults.py b/cli/generate-applications-defaults.py
index 7863bdae..df96c439 100644
--- a/cli/generate-applications-defaults.py
+++ b/cli/generate-applications-defaults.py
@@ -3,6 +3,7 @@
 import argparse
 import os
 import yaml
+import sys
 from pathlib import Path
 
 def load_yaml_file(path):
@@ -36,7 +37,13 @@ def main():
             continue
 
         vars_data = load_yaml_file(vars_main)
-        application_id = vars_data.get("application_id")
+        try:
+            application_id = vars_data.get("application_id")
+        except Exception as e:
+            # print the exception message
+            print(f"Warning: failed to read application_id from {vars_data} in {vars_main}.\nException: {e}", file=sys.stderr)
+            # exit with status 0
+            sys.exit(1)
 
         if not application_id:
             print(f"[!] Skipping {role_name}: application_id not defined in vars/main.yml")
diff --git a/filter_plugins/applications_if_group_and_deps.py b/filter_plugins/applications_if_group_and_deps.py
new file mode 100644
index 00000000..64723e9e
--- /dev/null
+++ b/filter_plugins/applications_if_group_and_deps.py
@@ -0,0 +1,80 @@
+from ansible.errors import AnsibleFilterError
+import os
+import sys
+import yaml
+
+class FilterModule(object):
+    def filters(self):
+        return {
+            'applications_if_group_and_deps': self.applications_if_group_and_deps,
+        }
+
+    def applications_if_group_and_deps(self, applications, group_names):
+        """
+        Return only those applications whose key is either:
+          1) directly in group_names, or
+          2) the application_id of any role reachable (recursively)
+             from any group in group_names via meta/dependencies.
+        Expects:
+          - applications: dict mapping application_id → config
+          - group_names: list of active role names
+        """
+        # validate inputs
+        if not isinstance(applications, dict):
+            raise AnsibleFilterError(f"Expected applications as dict, got {type(applications).__name__}")
+        if not isinstance(group_names, (list, tuple)):
+            raise AnsibleFilterError(f"Expected group_names as list/tuple, got {type(group_names).__name__}")
+
+        # locate roles directory (assume plugin sits in filter_plugins/)
+        plugin_dir = os.path.dirname(__file__)
+        project_root = os.path.abspath(os.path.join(plugin_dir, '..'))
+        roles_dir = os.path.join(project_root, 'roles')
+
+        # recursively collect all roles reachable from the given groups
+        def collect_roles(role, seen):
+            if role in seen:
+                return
+            seen.add(role)
+            meta_file = os.path.join(roles_dir, role, 'meta', 'main.yml')
+            if not os.path.isfile(meta_file):
+                return
+            try:
+                with open(meta_file) as f:
+                    meta = yaml.safe_load(f) or {}
+            except Exception:
+                return
+            for dep in meta.get('dependencies', []):
+                if isinstance(dep, str):
+                    dep_name = dep
+                elif isinstance(dep, dict):
+                    dep_name = dep.get('role') or dep.get('name')
+                else:
+                    continue
+                collect_roles(dep_name, seen)
+
+        included_roles = set()
+        for grp in group_names:
+            collect_roles(grp, included_roles)
+
+        # gather application_ids from those roles
+        included_app_ids = set()
+        for role in included_roles:
+            vars_file = os.path.join(roles_dir, role, 'vars', 'main.yml')
+            if not os.path.isfile(vars_file):
+                continue
+            try:
+                with open(vars_file) as f:
+                    vars_data = yaml.safe_load(f) or {}
+            except Exception:
+                continue
+            app_id = vars_data.get('application_id')
+            if isinstance(app_id, str) and app_id:
+                included_app_ids.add(app_id)
+
+        # build filtered result: include any application whose key is in group_names or in included_app_ids
+        result = {}
+        for app_key, cfg in applications.items():
+            if app_key in group_names or app_key in included_app_ids:
+                result[app_key] = cfg
+
+        return result
\ No newline at end of file
diff --git a/filter_plugins/generate_base_sld_domains.py b/filter_plugins/generate_base_sld_domains.py
index 6c72e332..cc2253ef 100644
--- a/filter_plugins/generate_base_sld_domains.py
+++ b/filter_plugins/generate_base_sld_domains.py
@@ -5,33 +5,40 @@ class FilterModule(object):
     def filters(self):
         return {'generate_base_sld_domains': self.generate_base_sld_domains}
 
-    def generate_base_sld_domains(self, domains_dict, redirect_mappings):
+    def generate_base_sld_domains(self, domains_list):
         """
-        Flatten domains_dict und redirect_mappings, extrahiere SLDs (z.B. example.com),
-        dedupe und sortiere.
+        Given a list of hostnames, extract the second-level domain (SLD.TLD) for any hostname
+        with two or more labels, return single-label hostnames as-is, and reject IPs,
+        empty or malformed strings, and non-strings. Deduplicate and sort.
         """
-        def _flatten(domains):
-            flat = []
-            for v in (domains or {}).values():
-                if isinstance(v, str):
-                    flat.append(v)
-                elif isinstance(v, list):
-                    flat.extend(v)
-                elif isinstance(v, dict):
-                    flat.extend(v.values())
-            return flat
+        if not isinstance(domains_list, list):
+            raise AnsibleFilterError(
+                f"generate_base_sld_domains expected a list, got {type(domains_list).__name__}"
+            )
 
-        try:
-            flat = _flatten(domains_dict)
-            for mapping in redirect_mappings or []:
-                src = mapping.get('source')
-                if isinstance(src, str):
-                    flat.append(src)
-                elif isinstance(src, list):
-                    flat.extend(src)
+        ip_pattern = re.compile(r'^\d{1,3}(?:\.\d{1,3}){3}$')
+        results = set()
 
-            pattern = re.compile(r'^(?:.*\.)?([^.]+\.[^.]+)$')
-            slds = {m.group(1) for d in flat if (m := pattern.match(d))}
-            return sorted(slds)
-        except Exception as exc:
-            raise AnsibleFilterError(f"generate_base_sld_domains failed: {exc}")
+        for hostname in domains_list:
+            # type check
+            if not isinstance(hostname, str):
+                raise AnsibleFilterError(f"Invalid domain entry (not a string): {hostname!r}")
+
+            # malformed or empty
+            if not hostname or hostname.startswith('.') or hostname.endswith('.') or '..' in hostname:
+                raise AnsibleFilterError(f"Invalid domain entry (malformed): {hostname!r}")
+
+            # IP addresses disallowed
+            if ip_pattern.match(hostname):
+                raise AnsibleFilterError(f"IP addresses not allowed: {hostname!r}")
+
+            # single-label hostnames
+            labels = hostname.split('.')
+            if len(labels) == 1:
+                results.add(hostname)
+            else:
+                # always keep only the last two labels (SLD.TLD)
+                sld = ".".join(labels[-2:])
+                results.add(sld)
+
+        return sorted(results)
\ No newline at end of file
diff --git a/filter_plugins/group_domain_filters.py b/filter_plugins/group_domain_filters.py
deleted file mode 100644
index c8b0f464..00000000
--- a/filter_plugins/group_domain_filters.py
+++ /dev/null
@@ -1,97 +0,0 @@
-from ansible.errors import AnsibleFilterError
-import sys
-import os
-import yaml
-
-class FilterModule(object):
-
-    def filters(self):
-        return {
-            "add_domain_if_group": self.add_domain_if_group,
-        }
-
-    @staticmethod
-    def add_domain_if_group(domains_dict, domain_key, domain_value, group_names):
-        """
-        Add {domain_key: domain_value} to domains_dict if either:
-          1) domain_key is in group_names (direct inclusion), or
-          2) domain_key is among collected application_id values of roles
-             reachable from any group in group_names via recursive dependencies.
-
-        Parameters:
-          domains_dict: existing dict of domains
-          domain_key:   name of the application to check
-          domain_value: domain or dict/list of domains to assign
-          group_names:  list of active group (role/application) names
-        """
-        try:
-            result = dict(domains_dict)
-
-            # Direct group match: if the application name itself is in group_names
-            if domain_key in group_names:
-                result[domain_key] = domain_value
-                return result
-
-            # Determine plugin directory based on filter plugin module if available
-            plugin_dir = None
-            for module in sys.modules.values():
-                fm = getattr(module, 'FilterModule', None)
-                if fm is not None:
-                    try:
-                        # Access staticmethod, compare underlying function
-                        if getattr(fm, 'add_domain_if_group') is DomainFilterUtil.add_domain_if_group:
-                            plugin_dir = os.path.dirname(module.__file__)
-                            break
-                    except Exception:
-                        continue
-
-            if plugin_dir:
-                # The plugin_dir is the filter_plugins directory; project_root is one level up
-                project_root = os.path.abspath(os.path.join(plugin_dir, '..'))
-            else:
-                # Fallback: locate project root relative to this utility file
-                plugin_dir = os.path.dirname(__file__)
-                project_root = os.path.abspath(os.path.join(plugin_dir, '..'))
-
-            roles_dir = os.path.join(project_root, 'roles')
-
-            # Collect all roles reachable from the active groups
-            def collect_roles(role_name, collected):
-                if role_name in collected:
-                    return
-                collected.add(role_name)
-                meta_path = os.path.join(roles_dir, role_name, 'meta', 'main.yml')
-                if os.path.isfile(meta_path):
-                    with open(meta_path) as f:
-                        meta = yaml.safe_load(f) or {}
-                        for dep in meta.get('dependencies', []):
-                            if isinstance(dep, str):
-                                dep_name = dep
-                            elif isinstance(dep, dict):
-                                dep_name = dep.get('role') or dep.get('name')
-                            else:
-                                continue
-                            collect_roles(dep_name, collected)
-
-            included_roles = set()
-            for grp in group_names:
-                collect_roles(grp, included_roles)
-
-            # Gather application_ids from each included role
-            app_ids = set()
-            for role in included_roles:
-                vars_main = os.path.join(roles_dir, role, 'vars', 'main.yml')
-                if os.path.isfile(vars_main):
-                    with open(vars_main) as f:
-                        vars_data = yaml.safe_load(f) or {}
-                        app_id = vars_data.get('application_id')
-                        if app_id:
-                            app_ids.add(app_id)
-
-            # Indirect inclusion: match by application_id
-            if domain_key in app_ids:
-                result[domain_key] = domain_value
-
-            return result
-        except Exception as exc:
-            raise AnsibleFilterError(f"add_domain_if_group failed: {exc}")
\ No newline at end of file
diff --git a/filter_plugins/load_configuration.py b/filter_plugins/load_configuration.py
new file mode 100644
index 00000000..78c9ddb9
--- /dev/null
+++ b/filter_plugins/load_configuration.py
@@ -0,0 +1,122 @@
+import os
+import yaml
+import re
+from ansible.errors import AnsibleFilterError
+
+# in-memory cache: application_id → (parsed_yaml, is_nested)
+_cfg_cache = {}
+
+def load_configuration(application_id, key):
+    if not isinstance(key, str):
+        raise AnsibleFilterError("Key must be a dotted-string, e.g. 'features.matomo'")
+
+    # locate roles/
+    here = os.path.dirname(__file__)
+    root = os.path.abspath(os.path.join(here, '..'))
+    roles_dir = os.path.join(root, 'roles')
+    if not os.path.isdir(roles_dir):
+        raise AnsibleFilterError(f"Roles directory not found at {roles_dir}")
+
+    # first time? load & cache
+    if application_id not in _cfg_cache:
+        config_path = None
+
+        # 1) primary: vars/main.yml declares it
+        for role in os.listdir(roles_dir):
+            mv = os.path.join(roles_dir, role, 'vars', 'main.yml')
+            if os.path.exists(mv):
+                try:
+                    md = yaml.safe_load(open(mv)) or {}
+                except Exception:
+                    md = {}
+                if md.get('application_id') == application_id:
+                    cf = os.path.join(roles_dir, role, 'vars', 'configuration.yml')
+                    if not os.path.exists(cf):
+                        raise AnsibleFilterError(
+                            f"Role '{role}' declares '{application_id}' but missing configuration.yml"
+                        )
+                    config_path = cf
+                    break
+
+        # 2) fallback nested
+        if config_path is None:
+            for role in os.listdir(roles_dir):
+                cf = os.path.join(roles_dir, role, 'vars', 'configuration.yml')
+                if not os.path.exists(cf):
+                    continue
+                try:
+                    dd = yaml.safe_load(open(cf)) or {}
+                except Exception:
+                    dd = {}
+                if isinstance(dd, dict) and application_id in dd:
+                    config_path = cf
+                    break
+
+        # 3) fallback flat
+        if config_path is None:
+            for role in os.listdir(roles_dir):
+                cf = os.path.join(roles_dir, role, 'vars', 'configuration.yml')
+                if not os.path.exists(cf):
+                    continue
+                try:
+                    dd = yaml.safe_load(open(cf)) or {}
+                except Exception:
+                    dd = {}
+                # flat style: dict with all non-dict values
+                if isinstance(dd, dict) and not any(isinstance(v, dict) for v in dd.values()):
+                    config_path = cf
+                    break
+
+        if config_path is None:
+            return None
+
+        # parse once
+        try:
+            parsed = yaml.safe_load(open(config_path)) or {}
+        except Exception as e:
+            raise AnsibleFilterError(f"Error loading configuration.yml at {config_path}: {e}")
+
+        # detect nested vs flat
+        is_nested = isinstance(parsed, dict) and (application_id in parsed)
+        _cfg_cache[application_id] = (parsed, is_nested)
+
+    parsed, is_nested = _cfg_cache[application_id]
+
+    # pick base entry
+    entry = parsed[application_id] if is_nested else parsed
+
+    # resolve dotted key
+    key_parts = key.split('.')
+    for part in key_parts:
+        # Check if part has an index (e.g., domains.canonical[0])
+        match = re.match(r'([^\[]+)\[([0-9]+)\]', part)
+        if match:
+            part, index = match.groups()
+            index = int(index)
+            if isinstance(entry, dict) and part in entry:
+                entry = entry[part]
+                # Check if entry is a list and access the index
+                if isinstance(entry, list) and 0 <= index < len(entry):
+                    entry = entry[index]
+                else:
+                    raise AnsibleFilterError(
+                        f"Index '{index}' out of range for key '{part}' in application '{application_id}'"
+                    )
+            else:
+                raise AnsibleFilterError(
+                    f"Key '{part}' not found under application '{application_id}'"
+                )
+        else:
+            if isinstance(entry, dict) and part in entry:
+                entry = entry[part]
+            else:
+                raise AnsibleFilterError(
+                    f"Key '{part}' not found under application '{application_id}'"
+                )
+
+    return entry
+
+
+class FilterModule(object):
+    def filters(self):
+        return {'load_configuration': load_configuration}
diff --git a/filter_plugins/merge_mapping.py b/filter_plugins/merge_mapping.py
new file mode 100644
index 00000000..60d79997
--- /dev/null
+++ b/filter_plugins/merge_mapping.py
@@ -0,0 +1,42 @@
+# filter_plugins/merge_mapping.py
+
+from ansible.errors import AnsibleFilterError
+
+def merge_mapping(list1, list2, key_name='source'):
+    """
+    Merge two lists of dicts on a given key.
+    - list1, list2: each must be a List[Dict]
+    - key_name: the field to match on
+    If both lists contain an item with the same key_name value,
+    their dictionaries are merged (fields from list2 overwrite or add to list1).
+    """
+    if not isinstance(list1, list) or not isinstance(list2, list):
+        raise AnsibleFilterError("merge_mapping expects two lists")
+
+    merged = {}
+    # First, copy items from list1
+    for item in list1:
+        if key_name not in item:
+            raise AnsibleFilterError(f"Item {item} is missing the key '{key_name}'")
+        merged[item[key_name]] = item.copy()
+
+    # Then merge in items from list2
+    for item in list2:
+        if key_name not in item:
+            raise AnsibleFilterError(f"Item {item} is missing the key '{key_name}'")
+        k = item[key_name]
+        if k in merged:
+            # update will overwrite existing fields or add new ones
+            merged[k].update(item)
+        else:
+            merged[k] = item.copy()
+
+    # Return as a list of dicts again
+    return list(merged.values())
+
+
+class FilterModule(object):
+    def filters(self):
+        return {
+            'merge_mapping': merge_mapping,
+        }
diff --git a/filter_plugins/redirect_filters.py b/filter_plugins/redirect_filters.py
deleted file mode 100644
index 1ac4f587..00000000
--- a/filter_plugins/redirect_filters.py
+++ /dev/null
@@ -1,37 +0,0 @@
-# roles/<your-role>/filter_plugins/redirect_filters.py
-from ansible.errors import AnsibleFilterError
-
-class FilterModule(object):
-    """
-    Custom filters for redirect domain mappings
-    """
-
-    def filters(self):
-        return {
-            "add_redirect_if_group": self.add_redirect_if_group,
-        }
-
-    @staticmethod
-    def add_redirect_if_group(redirect_list, group, source, target, group_names):
-        """
-        Append {"source": source, "target": target} to *redirect_list*
-        **only** if *group* is contained in *group_names*.
-
-        Usage in Jinja:
-          {{ redirect_list
-               | add_redirect_if_group('lam',
-                                       'ldap.' ~ primary_domain,
-                                       domains | get_domain('lam'),
-                                       group_names) }}
-        """
-        try:
-            # Make a copy so we don’t mutate the original list in place
-            redirects = list(redirect_list)
-
-            if group in group_names:
-                redirects.append({"source": source, "target": target})
-
-            return redirects
-
-        except Exception as exc:
-            raise AnsibleFilterError(f"add_redirect_if_group failed: {exc}")
diff --git a/group_vars/all/08_ports.yml b/group_vars/all/08_ports.yml
index 4b059ae0..1c8396ea 100644
--- a/group_vars/all/08_ports.yml
+++ b/group_vars/all/08_ports.yml
@@ -50,7 +50,7 @@ ports:
       keycloak:         8032
       lam:              8033
       phpmyadmin:       8034
-      snipe_it:         8035
+      snipe-it:         8035
       sphinx:           8036
       phpldapadmin:     8037
       fusiondirectory:  8038
diff --git a/group_vars/all/09_networks.yml b/group_vars/all/09_networks.yml
index 9ae1e84b..3c768bc9 100644
--- a/group_vars/all/09_networks.yml
+++ b/group_vars/all/09_networks.yml
@@ -62,7 +62,7 @@ defaults_networks:
       subnet: 192.168.102.128/28
     pgadmin:
       subnet: 192.168.102.144/28
-    snipe_it:
+    snipe-it:
       subnet: 192.168.102.160/28
     taiga:
       subnet: 192.168.102.176/28
diff --git a/group_vars/all/11_domains.yml b/group_vars/all/11_domains.yml
index d072e4c4..8e27575d 100644
--- a/group_vars/all/11_domains.yml
+++ b/group_vars/all/11_domains.yml
@@ -1,6 +1,2 @@
-defaults_domains: "{{ defaults_applications | canonical_domains_map(primary_domain) }}"
-
-defaults_redirect_domain_mappings: "{{ applications | domain_mappings(primary_domain) }}"
-
 # Domains which are deprecated and should be cleaned up
 deprecated_domains: []
\ No newline at end of file
diff --git a/group_vars/all/15_about.yml b/group_vars/all/15_about.yml
index e3c7e689..2c2dc3df 100644
--- a/group_vars/all/15_about.yml
+++ b/group_vars/all/15_about.yml
@@ -9,12 +9,12 @@ defaults_service_provider:
       city:         "Cybertown"
       postal_code:  "00001"
       country:      "Nexusland"
-    logo:           "{{ applications.assets_server.url | safe_var | safe_join('img/logo.png') }}"
+    logo:           "{{ applications['assets-server'].url | safe_var | safe_join('img/logo.png') }}"
   platform:    
     titel:          "CyMaIS Demo"
     subtitel:       "The Future of Self-Hosted Infrastructure. Secure. Automated. Sovereign."
-    logo:           "{{ applications.assets_server.url | safe_var | safe_join('img/logo.png') }}"
-    favicon:        "{{ applications.assets_server.url | safe_var | safe_join('img/favicon.ico') }}"
+    logo:           "{{ applications['assets-server'].url | safe_var | safe_join('img/logo.png') }}"
+    favicon:        "{{ applications['assets-server'].url | safe_var | safe_join('img/favicon.ico') }}"
   contact:
     bluesky: >-
       {{ ('@' ~ users.administrator.username ~ '.' ~ domains.bluesky.api)
diff --git a/roles/docker-bluesky/tasks/main.yml b/roles/docker-bluesky/tasks/main.yml
index 28243a36..7f451be9 100644
--- a/roles/docker-bluesky/tasks/main.yml
+++ b/roles/docker-bluesky/tasks/main.yml
@@ -1,4 +1,3 @@
----
 - name: "include docker-compose role"
   include_role: 
     name: docker-compose
@@ -10,8 +9,8 @@
     domain: "{{ item.domain }}"
     http_port: "{{ item.http_port }}"
   loop:
-    - { domain: domains.[application_id].api, http_port: ports.localhost.http.bluesky_api }
-    - { domain: domains.[application_id].web, http_port: ports.localhost.http.bluesky_web }
+    - { domain: "{{domains.[application_id].api", http_port: "{{ports.localhost.http.bluesky_api}}" }
+    - { domain: "{{domains.[application_id].web}}", http_port: "{{ports.localhost.http.bluesky_web}}" }
 
 # The following lines should be removed when the following issue is closed:
 # https://github.com/bluesky-social/pds/issues/52
diff --git a/roles/docker-bluesky/vars/main.yml b/roles/docker-bluesky/vars/main.yml
index 287e1e00..011d95ab 100644
--- a/roles/docker-bluesky/vars/main.yml
+++ b/roles/docker-bluesky/vars/main.yml
@@ -5,4 +5,4 @@ social_app_path:              "{{ docker_compose.directories.services }}/social-
 # https://github.com/bluesky-social/pds/issues/52
 pdsadmin_folder_path:         "{{ docker_compose.directories.volumes }}/pdsadmin"
 pdsadmin_file_path:           "{{pdsadmin_folder_path}}/pdsadmin"
-pdsadmin_temporary_tar_path:  "/tmp/pdsadmin.tar.gz"
\ No newline at end of file
+pdsadmin_temporary_tar_path:  "/tmp/pdsadmin.tar.gz"
diff --git a/roles/docker-mybb/tasks/setup-domain.yml b/roles/docker-mybb/tasks/setup-domain.yml
index 5fd54024..8eec856e 100644
--- a/roles/docker-mybb/tasks/setup-domain.yml
+++ b/roles/docker-mybb/tasks/setup-domain.yml
@@ -1,5 +1,3 @@
-{# receives https certificate and setup proxy with domain replace #}
-
 - name: "include role receive certbot certificate"
   include_role: 
     name: nginx-https-get-cert
diff --git a/roles/docker-portfolio/vars/menu_categories.yml b/roles/docker-portfolio/vars/menu_categories.yml
index cdbe5763..5b1b78ee 100644
--- a/roles/docker-portfolio/vars/menu_categories.yml
+++ b/roles/docker-portfolio/vars/menu_categories.yml
@@ -116,7 +116,7 @@ portfolio_menu_categories:
       - accounting
       - invoices
       - akaunting
-      - snipe_it
+      - snipe-it
       
   Events:
     description: "Event and ticket management tools"
diff --git a/roles/docker-snipe_it/Administration.md b/roles/docker-snipe-it/Administration.md
similarity index 100%
rename from roles/docker-snipe_it/Administration.md
rename to roles/docker-snipe-it/Administration.md
diff --git a/roles/docker-snipe_it/README.md b/roles/docker-snipe-it/README.md
similarity index 100%
rename from roles/docker-snipe_it/README.md
rename to roles/docker-snipe-it/README.md
diff --git a/roles/docker-snipe_it/meta/main.yml b/roles/docker-snipe-it/meta/main.yml
similarity index 100%
rename from roles/docker-snipe_it/meta/main.yml
rename to roles/docker-snipe-it/meta/main.yml
diff --git a/roles/docker-snipe_it/meta/schema.yml b/roles/docker-snipe-it/meta/schema.yml
similarity index 100%
rename from roles/docker-snipe_it/meta/schema.yml
rename to roles/docker-snipe-it/meta/schema.yml
diff --git a/roles/docker-snipe_it/tasks/main.yml b/roles/docker-snipe-it/tasks/main.yml
similarity index 100%
rename from roles/docker-snipe_it/tasks/main.yml
rename to roles/docker-snipe-it/tasks/main.yml
diff --git a/roles/docker-snipe_it/templates/docker-compose.yml.j2 b/roles/docker-snipe-it/templates/docker-compose.yml.j2
similarity index 85%
rename from roles/docker-snipe_it/templates/docker-compose.yml.j2
rename to roles/docker-snipe-it/templates/docker-compose.yml.j2
index f8e899b7..05527ec0 100644
--- a/roles/docker-snipe_it/templates/docker-compose.yml.j2
+++ b/roles/docker-snipe-it/templates/docker-compose.yml.j2
@@ -5,12 +5,12 @@ services:
 {% include 'roles/docker-central-database/templates/services/' + database_type + '.yml.j2' %}
 
   application:
-    image: grokability/snipe-it:{{applications.snipe_it.version}}
+    image: grokability/snipe-it:{{applications[application_id].version}}
 {% include 'roles/docker-compose/templates/services/base.yml.j2' %}
     volumes:
       - data:/var/lib/snipeit
     ports:
-      - "127.0.0.1:{{ports.localhost.http.snipe_it}}:80"
+      - "127.0.0.1:{{ports.localhost.http[application_id]}}:80"
 {% include 'templates/docker/container/depends-on-database-redis.yml.j2' %}
 {% include 'templates/docker/container/networks.yml.j2' %}
     healthcheck:
diff --git a/roles/docker-snipe_it/templates/env.j2 b/roles/docker-snipe-it/templates/env.j2
similarity index 100%
rename from roles/docker-snipe_it/templates/env.j2
rename to roles/docker-snipe-it/templates/env.j2
diff --git a/roles/docker-snipe_it/vars/configuration.yml b/roles/docker-snipe-it/vars/configuration.yml
similarity index 100%
rename from roles/docker-snipe_it/vars/configuration.yml
rename to roles/docker-snipe-it/vars/configuration.yml
diff --git a/roles/docker-snipe-it/vars/main.yml b/roles/docker-snipe-it/vars/main.yml
new file mode 100644
index 00000000..fe8e3893
--- /dev/null
+++ b/roles/docker-snipe-it/vars/main.yml
@@ -0,0 +1,3 @@
+application_id:     "snipe-it"
+database_password:  "{{applications[application_id].credentials.database_password}}"
+database_type:      "mariadb"
\ No newline at end of file
diff --git a/roles/docker-snipe_it/vars/main.yml b/roles/docker-snipe_it/vars/main.yml
deleted file mode 100644
index 1ab0f88e..00000000
--- a/roles/docker-snipe_it/vars/main.yml
+++ /dev/null
@@ -1,3 +0,0 @@
-application_id:     "snipe_it"
-database_password:  "{{applications.snipe_it.credentials.database_password}}"
-database_type:      "mariadb"
\ No newline at end of file
diff --git a/roles/health-nginx/templates/health-nginx.py.j2 b/roles/health-nginx/templates/health-nginx.py.j2
index 421b173e..96fc2a35 100644
--- a/roles/health-nginx/templates/health-nginx.py.j2
+++ b/roles/health-nginx/templates/health-nginx.py.j2
@@ -47,7 +47,7 @@ for filename in os.listdir(config_path):
         # Prepare the URL and expected status codes
         url = f"{{ web_protocol }}://{domain}"
         
-        redirected_domains = [domain['source'] for domain in {{redirect_domain_mappings}}]
+        redirected_domains = [domain['source'] for domain in {{current_play_redirect_domain_mappings}}]
         {%- if domains.mailu | safe_var | bool %}
         redirected_domains.append("{{domains | get_domain('mailu')}}")
         {%- endif %}
diff --git a/roles/letsencrypt/vars/main.yml b/roles/letsencrypt/vars/main.yml
index 52212be1..80071148 100644
--- a/roles/letsencrypt/vars/main.yml
+++ b/roles/letsencrypt/vars/main.yml
@@ -4,4 +4,5 @@ caa_entries:
 #  - tag: issuewild
 #    value: "letsencrypt.org"
 #  - tag: iodef
-#    value: "mailto:{{ users.administrator.email }}"
\ No newline at end of file
+#    value: "mailto:{{ users.administrator.email }}"
+base_sld_domains: "{{ current_play_domains_all | generate_base_sld_domains }}"
\ No newline at end of file
diff --git a/roles/nginx-https-get-cert/tasks/flavors/san.yml b/roles/nginx-https-get-cert/tasks/flavors/san.yml
index 241c91ef..6a0af9fc 100644
--- a/roles/nginx-https-get-cert/tasks/flavors/san.yml
+++ b/roles/nginx-https-get-cert/tasks/flavors/san.yml
@@ -8,7 +8,7 @@
 - name: Generate SAN certificate with certbundle
   command: >-
     certbundle
-    --domains "{{ all_domains | join(',') }}"
+    --domains "{{ current_play_domains_all | join(',') }}"
     --certbot-email "{{ users.administrator.email }}"
     --certbot-acme-challenge-method "{{ certbot_acme_challenge_method }}"
     --chunk-size 100
diff --git a/roles/nginx-modifier-matomo/vars/main.yml b/roles/nginx-modifier-matomo/vars/main.yml
index 3e097b0a..5e7d66f6 100644
--- a/roles/nginx-modifier-matomo/vars/main.yml
+++ b/roles/nginx-modifier-matomo/vars/main.yml
@@ -1,2 +1,2 @@
 base_domain:      "{{ domain | regex_replace('^(?:.*\\.)?(.+\\..+)$', '\\1') }}"
-verification_url: "{{ web_protocol }}://{{domains | get_domain('mastodon')}}/index.php?module=API&method=SitesManager.getSitesIdFromSiteUrl&url=https://{{base_domain}}&format=json&token_auth={{applications.matomo.credentials.auth_token}}"
\ No newline at end of file
+verification_url: "{{ web_protocol }}://{{domains | get_domain('matomo')}}/index.php?module=API&method=SitesManager.getSitesIdFromSiteUrl&url=https://{{base_domain}}&format=json&token_auth={{applications.matomo.credentials.auth_token}}"
\ No newline at end of file
diff --git a/roles/nginx-redirect-www/tasks/main.yml b/roles/nginx-redirect-www/tasks/main.yml
index 33b6b7f4..70030245 100644
--- a/roles/nginx-redirect-www/tasks/main.yml
+++ b/roles/nginx-redirect-www/tasks/main.yml
@@ -1,7 +1,7 @@
 ---
-- name: Filter www-prefixed domains from all_domains
+- name: Filter www-prefixed domains from current_play_domains_all
   set_fact:
-    www_domains: "{{ all_domains | select('match', '^www\\.') | list }}"
+    www_domains: "{{ current_play_domains_all | select('match', '^www\\.') | list }}"
 
 - name: Include nginx-redirect-domains role for www-to-bare redirects
   include_role:
diff --git a/roles/nginx-serve-assets/vars/configuration.yml b/roles/nginx-serve-assets/vars/configuration.yml
index d7471148..57142bbf 100644
--- a/roles/nginx-serve-assets/vars/configuration.yml
+++ b/roles/nginx-serve-assets/vars/configuration.yml
@@ -1,4 +1,3 @@
-source_directory: "{{ playbook_dir }}/assets"                             # Directory from which the assets will be copied
-url: >-
-  {{ (web_protocol ~ '://' ~ domains.file_server | safe_var ~ '/assets')
-     if domains.file_server | safe_var else '' }}
+source_directory: "{{ playbook_dir }}/assets"
+url: "{{ web_protocol ~ '://' ~ 'file-server' 
+   | load_configuration('domains.canonical[0]') ~ '/assets' }}"
\ No newline at end of file
diff --git a/roles/nginx-serve-assets/vars/main.yml b/roles/nginx-serve-assets/vars/main.yml
index f826c784..266789a6 100644
--- a/roles/nginx-serve-assets/vars/main.yml
+++ b/roles/nginx-serve-assets/vars/main.yml
@@ -1,3 +1,3 @@
-application_id:     "assets_server"                                         # Application identifier
+application_id:     "assets-server"                                         # Application identifier
 source_directory:   "{{ applications[application_id].source_directory }}/"  # Source directory from which the files are coming from
 target_directory:   "{{ nginx.directories.data.files }}assets"              # Directory to which the files will be copied
diff --git a/roles/nginx-serve-files/README.md b/roles/nginx-serve-files/README.md
index 0dcd40d8..a1cc7a1a 100644
--- a/roles/nginx-serve-files/README.md
+++ b/roles/nginx-serve-files/README.md
@@ -31,5 +31,5 @@ The Nginx File Server role is ideal for hosting static files, sharing resources
 
 - [Nginx Official Website](https://nginx.org/)
 - [Let's Encrypt](https://letsencrypt.org/)
-- [HTTP File Server (Wikipedia)](https://en.wikipedia.org/wiki/HTTP_File_Server)
+- [HTTP File Server (Wikipedia)](https://en.wikipedia.org/wiki/HTTP_file-server)
 - [HTTPS (Wikipedia)](https://en.wikipedia.org/wiki/HTTPS)
diff --git a/roles/nginx-serve-files/vars/main.yml b/roles/nginx-serve-files/vars/main.yml
index 6682fe0d..c8609e8b 100644
--- a/roles/nginx-serve-files/vars/main.yml
+++ b/roles/nginx-serve-files/vars/main.yml
@@ -1,2 +1,2 @@
-application_id: "file_server"
-domain:         "{{ domains | get_domain(application_id) }}"
\ No newline at end of file
+application_id: "file-server"
+domain:         "{{ domains | get_domain(application_id) }}"
diff --git a/tasks/constructor.yml b/tasks/constructor.yml
index febf1471..248a9cf5 100644
--- a/tasks/constructor.yml
+++ b/tasks/constructor.yml
@@ -9,44 +9,55 @@
     set_fact:
       system_email: "{{ default_system_email | combine(system_email | default({}, true), recursive=True) }}"
 
+  - name: Merge current play applications
+    set_fact:
+      current_play_applications: >-
+        {{ 
+          defaults_applications | 
+          combine(applications | default({}, true), recursive=True) |
+          applications_if_group_and_deps(group_names)
+          }}
+
+  - name: Merge current play domain definitions
+    set_fact:
+      current_play_domains: >- 
+        {{  current_play_applications |
+            canonical_domains_map(primary_domain) | 
+            combine(domains | default({}, true), recursive=True) 
+        }}
+
+  - name: Set current play all domains incl. www redirect if enabled
+    set_fact:
+      current_play_domains_all: >-
+        {{ 
+          current_play_domains  | 
+          generate_all_domains(
+              ('www_redirect' in group_names)
+          )
+        }}
+  
+  - name: Set current play redirect domain mappings 
+    set_fact:
+      current_play_redirect_domain_mappings: >-
+        {{ 
+          current_play_applications |
+          domain_mappings(primary_domain) | 
+          merge_mapping(redirect_domain_mappings, 'source') 
+        }}
+
   - name: Merge application definitions
     set_fact:
       applications: "{{ defaults_applications | combine(applications | default({}, true), recursive=True) }}"
 
-  - name: Merge domain definitions
+  - name: Merge domain definitions for all domains
     set_fact:
-      domains: "{{ defaults_domains | combine(domains | default({}, true), recursive=True) }}"
-
-  - name: Merge redirect domain definitions into dictionary
-    set_fact:
-      combined_mapping: >-
-        {{
-          (defaults_redirect_domain_mappings | items2dict(key_name='source', value_name='target'))
-          | combine(
-              (redirect_domain_mappings | default([]) | items2dict(key_name='source', value_name='target')),
-              recursive=True
-            )
+      domains: >-
+        {{ 
+          defaults_applications | 
+          canonical_domains_map(primary_domain) | 
+          combine(domains | default({}, true), recursive=True) 
         }}
 
-  - name: Transform combined mapping to list with source and target keys
-    set_fact:
-      redirect_domain_mappings: "{{ redirect_domain_mappings | default([]) + [ {'source': item.key, 'target': item.value} ] }}"
-    loop: "{{ combined_mapping | dict2items }}"
-
-# @todo implement
-#  - name: Ensure features.integrated is set based on group membership
-#    set_fact:
-#      applications: "{{ applications | combine({ item.key: updated_app }, recursive=True) }}"
-#    vars:
-#      original_app: "{{ applications[item.key] | default({}) }}"
-#      original_features: "{{ original_app.features | default({}) }}"
-#      needs_integration: original_features.integrated is not defined
-#      updated_features: >-
-#        {{ original_features | combine({'integrated': (item.key in group_names)}) if needs_integration else original_features }}
-#      updated_app: >-
-#        {{ original_app | combine({'features': updated_features}) }}
-#    loop: "{{ applications | dict2items }}"
-
   - name: Merge networks definitions
     set_fact:
       networks: "{{ defaults_networks | combine(networks | default({}, true), recursive=True) }}"
@@ -63,34 +74,6 @@
     set_fact:
       service_provider: "{{ defaults_service_provider | combine(service_provider | default({}, true), recursive=True) }}"
 
-  - name: Build base_sld_domains (sld.tld) in one go
-    set_fact:
-      base_sld_domains: >-
-        {{ domains
-           | generate_base_sld_domains(redirect_domain_mappings)
-        }}
-
-  - name: Set all domains incl. www redirect if enabled
-    set_fact:
-      all_domains: >-
-        {{ domains
-          | generate_all_domains(
-              ('www_redirect' in group_names)
-            )
-        }}
-
-  - name: "Merged Variables"
-    # Add new merged variables here
-    debug:
-      msg:
-        domains:          "{{ domains }}"
-        applications:     "{{ applications }}"
-        oidc:             "{{ oidc }}"
-        service_provider: "{{ service_provider }}"
-        users:            "{{ users }}"
-        all_domains:      "{{ all_domains }}"
-    when: enable_debug | bool
-
 - name: init root user
   include_role:
     name: user-root
diff --git a/tasks/server.yml b/tasks/server.yml
index a864f5f9..f410ec93 100644
--- a/tasks/server.yml
+++ b/tasks/server.yml
@@ -32,7 +32,7 @@
   include_role:
     name: nginx-redirect-domains
   vars:
-    domain_mappings: "{{redirect_domain_mappings}}"
+    domain_mappings: "{{current_play_redirect_domain_mappings}}"
 
 - name: setup www redirect 
   when: ("www_redirect" in group_names)
diff --git a/tests/integration/test_yaml_syntax.py b/tests/integration/test_yaml_syntax.py
new file mode 100644
index 00000000..f1e5d0e8
--- /dev/null
+++ b/tests/integration/test_yaml_syntax.py
@@ -0,0 +1,47 @@
+import os
+import sys
+import unittest
+import yaml
+
+class TestYamlSyntax(unittest.TestCase):
+    def test_all_yml_files_are_valid_yaml(self):
+        """
+        Walk the entire repository, find all *.yml files and try to parse them
+        with yaml.safe_load(). Fail the test if any file contains invalid YAML.
+        """
+        repo_root = os.path.abspath(
+            os.path.join(os.path.dirname(__file__), '..', '..')
+        )
+
+        invalid = []
+
+        for dirpath, dirnames, filenames in os.walk(repo_root):
+            # skip hidden directories (like .git, .venv, etc.)
+            dirnames[:] = [d for d in dirnames if not d.startswith('.')]
+            for fname in filenames:
+                if not fname.endswith('.yml'):
+                    continue
+                full = os.path.join(dirpath, fname)
+                # skip any large auto‐generated files if needed:
+                # if 'some/path/to/skip' in full: continue
+
+                try:
+                    with open(full, 'r') as f:
+                        yaml.safe_load(f)
+                except yaml.YAMLError as e:
+                    invalid.append((full, str(e)))
+                except Exception as e:
+                    invalid.append((full, f"Unexpected error: {e}"))
+
+        if invalid:
+            msg_lines = [
+                f"{path}: {err.splitlines()[0]}"  # just the first line of the error
+                for path, err in invalid
+            ]
+            self.fail(
+                "Found invalid YAML in the following files:\n" +
+                "\n".join(msg_lines)
+            )
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/unit/test_applications_if_group_and_deps.py b/tests/unit/test_applications_if_group_and_deps.py
new file mode 100644
index 00000000..7f617b52
--- /dev/null
+++ b/tests/unit/test_applications_if_group_and_deps.py
@@ -0,0 +1,83 @@
+import os
+import sys
+import unittest
+from unittest.mock import patch, mock_open
+from ansible.errors import AnsibleFilterError
+
+# ensure filter_plugins is on the path
+dir_path = os.path.abspath(
+    os.path.join(os.path.dirname(__file__), '../../filter_plugins')
+)
+sys.path.insert(0, dir_path)
+
+from applications_if_group_and_deps import FilterModule
+
+class TestApplicationsIfGroupAndDeps(unittest.TestCase):
+    def setUp(self):
+        self.filter = FilterModule()
+        # minimal applications dict
+        self.apps = {
+            'app1': {'foo': 'bar'},
+            'app2': {'baz': 'qux'},
+            'roleA': {'some': 'cfg'},
+        }
+
+    def test_invalid_inputs(self):
+        with self.assertRaises(AnsibleFilterError):
+            self.filter.applications_if_group_and_deps('not a dict', [])
+        with self.assertRaises(AnsibleFilterError):
+            self.filter.applications_if_group_and_deps({}, 'not a list')
+
+    def test_direct_inclusion(self):
+        # if an app key is directly in group_names it should be returned
+        groups = ['app1', 'unrelated']
+        result = self.filter.applications_if_group_and_deps(self.apps, groups)
+        self.assertEqual(set(result.keys()), {'app1'})
+
+    @patch('applications_if_group_and_deps.yaml.safe_load')
+    @patch('applications_if_group_and_deps.open', new_callable=mock_open)
+    @patch('applications_if_group_and_deps.os.path.isfile')
+    def test_indirect_inclusion_via_dependencies(self, mock_isfile, mock_file, mock_yaml):
+        """
+        Simulate that group 'groupX' has a dependency on 'roleA', and that
+        roleA's vars/main.yml contains application_id: 'roleA'.
+        Then passing group_names=['groupX'] should include 'roleA'.
+        """
+        # pretend both meta/main.yml and vars/main.yml exist
+        mock_isfile.return_value = True
+
+        # safe_load() calls:
+        # 1) groupX/meta/main.yml → dependencies ['roleA']
+        # 2) roleA/meta/main.yml  → dependencies []
+        # 3) roleA/vars/main.yml  → application_id 'roleA'
+        mock_yaml.side_effect = [
+            {'dependencies': ['roleA']},
+            {'dependencies': []},
+            {'application_id': 'roleA'}
+        ]
+
+        result = self.filter.applications_if_group_and_deps(self.apps, ['groupX'])
+        self.assertEqual(set(result.keys()), {'roleA'})
+
+    @patch('applications_if_group_and_deps.yaml.safe_load')
+    @patch('applications_if_group_and_deps.open', new_callable=mock_open)
+    @patch('applications_if_group_and_deps.os.path.isfile')
+    def test_no_vars_file(self, mock_isfile, mock_file, mock_yaml):
+        """
+        If a meta/main.yml dependency exists but vars/main.yml is missing,
+        that role won't contribute an application_id, so nothing is returned.
+        """
+        # meta exists, vars does not
+        def isfile_side(path):
+            return path.endswith('meta/main.yml')
+        mock_isfile.side_effect = isfile_side
+
+        # meta declares dependency
+        mock_yaml.return_value = {'dependencies': ['roleA']}
+
+        result = self.filter.applications_if_group_and_deps(self.apps, ['groupX'])
+        self.assertEqual(result, {})
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/tests/unit/test_domain_filters_base_sld_domains.py b/tests/unit/test_domain_filters_base_sld_domains.py
index fd4ce1ff..44d5e010 100644
--- a/tests/unit/test_domain_filters_base_sld_domains.py
+++ b/tests/unit/test_domain_filters_base_sld_domains.py
@@ -5,44 +5,66 @@ import os
 # Ensure filter_plugins directory is on the path
 sys.path.insert(
     0,
-    os.path.abspath(os.path.join(os.path.dirname(__file__), '../../filter_plugins'))
+    os.path.abspath(os.path.join(os.path.dirname(__file__), '../filter_plugins'))
 )
 
 from generate_base_sld_domains import FilterModule
+from ansible.errors import AnsibleFilterError
 
 class TestGenerateBaseSldDomains(unittest.TestCase):
     def setUp(self):
         self.filter = FilterModule().generate_base_sld_domains
 
-    def test_simple_string_and_redirect(self):
-        domains = {'app': 'sub.example.com'}
-        redirects = [{'source': 'alias.example.com'}]
-        result = self.filter(domains, redirects)
+    def test_simple_list(self):
+        domains = [
+            'sub.example.com',
+            'alias.example.com',
+            'example.com'
+        ]
+        result = self.filter(domains)
         self.assertEqual(result, ['example.com'])
 
-    def test_without_redirect_mappings(self):
-        domains = {
-            'a': 'a.co',
-            'b': ['b.co', 'sub.c.co'],
-            'c': {'x': 'x.co'}
-        }
-        result = self.filter(domains, None)
-        self.assertEqual(result, ['a.co', 'b.co', 'c.co', 'x.co'])
+    def test_mixed_tlds_and_subdomains(self):
+        domains = [
+            'a.co', 'b.co', 'sub.b.co', 'x.co', 'www.x.co'
+        ]
+        result = self.filter(domains)
+        self.assertEqual(result, ['a.co', 'b.co', 'x.co'])
 
-    def test_redirect_list_sources(self):
-        domains = {'app': 'app.domain.org'}
-        redirects = [{'source': ['alias.domain.org', 'deep.sub.example.net']}]
-        result = self.filter(domains, redirects)
-        self.assertEqual(result, ['domain.org', 'example.net'])
+    def test_invalid_non_string_raise(self):
+        for bad in [42, None]:
+            with self.assertRaises(AnsibleFilterError):
+                self.filter([bad])
 
-    def test_duplicate_entries_and_sorting(self):
-        domains = {
-            'x': ['one.com', 'sub.one.com'],
-            'y': 'two.com',
-            'z': {'k': 'one.com'}
-        }
-        redirects = [{'source': 'deep.two.com'}]
-        result = self.filter(domains, redirects)
+    def test_localhost_allowed(self):
+        domains = ['localhost']
+        result = self.filter(domains)
+        self.assertEqual(result, ['localhost'])
+
+    def test_ip_raises(self):
+        with self.assertRaises(AnsibleFilterError):
+            self.filter(['127.0.0.1'])
+
+    def test_nested_subdomains(self):
+        domains = ['sub.sub2.one']
+        result = self.filter(domains)
+        self.assertEqual(result, ['sub2.one'])
+
+    def test_deeply_nested_subdomains(self):
+        domains = ['sub3.sub2.sub1.one']
+        result = self.filter(domains)
+        self.assertEqual(result, ['sub1.one'])
+
+    def test_empty_and_malformed_raise(self):
+        for bad in ['', '.', '...']:
+            with self.assertRaises(AnsibleFilterError):
+                self.filter([bad])
+
+    def test_sorting_and_duplicates(self):
+        domains = [
+            'one.com', 'sub.one.com', 'two.com', 'deep.two.com', 'one.com'
+        ]
+        result = self.filter(domains)
         self.assertEqual(result, ['one.com', 'two.com'])
 
 if __name__ == '__main__':
diff --git a/tests/unit/test_group_domain_filters.py b/tests/unit/test_group_domain_filters.py
deleted file mode 100644
index f35c9187..00000000
--- a/tests/unit/test_group_domain_filters.py
+++ /dev/null
@@ -1,51 +0,0 @@
-import unittest
-
-from filter_plugins.group_domain_filters import FilterModule
-
-class TestAddDomainIfGroup(unittest.TestCase):
-    def setUp(self):
-        self.filter = FilterModule().filters()["add_domain_if_group"]
-
-    def test_add_string_value(self):
-        result = self.filter({}, "akaunting", "accounting.example.org", ["akaunting"])
-        self.assertEqual(result, {"akaunting": "accounting.example.org"})
-
-    def test_add_list_value(self):
-        result = self.filter({}, "mastodon", ["microblog.example.org"], ["mastodon"])
-        self.assertEqual(result, {"mastodon": ["microblog.example.org"]})
-
-    def test_add_dict_value(self):
-        result = self.filter({}, "bluesky", {"web": "bskyweb.example.org", "api": "bluesky.example.org"}, ["bluesky"])
-        self.assertEqual(result, {"bluesky": {"web": "bskyweb.example.org", "api": "bluesky.example.org"}})
-
-    def test_ignore_if_not_in_group(self):
-        result = self.filter({}, "akaunting", "accounting.example.org", ["wordpress"])
-        self.assertEqual(result, {})
-
-    def test_merge_with_existing(self):
-        initial = {"wordpress": ["blog.example.org"]}
-        result = self.filter(initial, "akaunting", "accounting.example.org", ["akaunting"])
-        self.assertEqual(result, {
-            "wordpress": ["blog.example.org"],
-            "akaunting": "accounting.example.org"
-        })
-
-    def test_dict_is_not_mutated(self):
-        base = {"keycloak": "auth.example.org"}
-        copy = dict(base)  # make a copy for comparison
-        _ = self.filter(base, "akaunting", "accounting.example.org", ["akaunting"])
-        self.assertEqual(base, copy)  # original must stay unchanged
-
-    def test_multiple_adds_accumulate(self):
-        result = {}
-        result = self.filter(result, "akaunting", "accounting.example.org", ["akaunting", "wordpress"])
-        result = self.filter(result, "wordpress", ["blog.example.org"], ["akaunting", "wordpress"])
-        result = self.filter(result, "bluesky", {"web": "bskyweb.example.org", "api": "bluesky.example.org"}, ["bluesky"])
-        self.assertEqual(result, {
-            "akaunting": "accounting.example.org",
-            "wordpress": ["blog.example.org"],
-            "bluesky": {"web": "bskyweb.example.org", "api": "bluesky.example.org"},
-        })
-
-if __name__ == "__main__":
-    unittest.main()
diff --git a/tests/unit/test_group_domain_filters_recursive.py b/tests/unit/test_group_domain_filters_recursive.py
deleted file mode 100644
index 99946022..00000000
--- a/tests/unit/test_group_domain_filters_recursive.py
+++ /dev/null
@@ -1,79 +0,0 @@
-import os
-import tempfile
-import shutil
-import yaml
-import unittest
-
-# Import the filter module
-import filter_plugins.group_domain_filters as gdf_module
-
-class TestAddDomainIfGroupRecursive(unittest.TestCase):
-    def setUp(self):
-        # Create a temporary project structure
-        self.tempdir = tempfile.mkdtemp()
-        fp_dir = os.path.join(self.tempdir, 'filter_plugins')
-        roles_dir = os.path.join(self.tempdir, 'roles')
-        os.makedirs(fp_dir, exist_ok=True)
-        os.makedirs(roles_dir, exist_ok=True)
-        # Point module __file__ so plugin_dir resolves correctly
-        gdf_module.__file__ = os.path.join(fp_dir, 'group_domain_filters.py')
-        self.roles_dir = roles_dir
-
-    def tearDown(self):
-        shutil.rmtree(self.tempdir)
-
-    def write_role(self, role_name, dependencies, application_id):
-        """
-        Helper: write a role directory with meta/main.yml and vars/main.yml
-        """
-        meta_dir = os.path.join(self.roles_dir, role_name, 'meta')
-        vars_dir = os.path.join(self.roles_dir, role_name, 'vars')
-        os.makedirs(meta_dir, exist_ok=True)
-        os.makedirs(vars_dir, exist_ok=True)
-        # Write meta/main.yml
-        with open(os.path.join(meta_dir, 'main.yml'), 'w') as f:
-            yaml.safe_dump({'dependencies': dependencies}, f)
-        # Write vars/main.yml
-        with open(os.path.join(vars_dir, 'main.yml'), 'w') as f:
-            yaml.safe_dump({'application_id': application_id}, f)
-
-    def test_direct_application_id_in_group_names(self):
-        # If domain_key (application_id) is directly in group_names
-        result = gdf_module.FilterModule.add_domain_if_group({}, 'app1', 'domain1', ['app1'])
-        self.assertEqual(result, {'app1': 'domain1'})
-
-    def test_indirect_dependency_application_id(self):
-        # roleA depends on roleB; roleB has application_id 'appB'
-        self.write_role('roleA', ['roleB'], 'appA')
-        self.write_role('roleB', [], 'appB')
-        # group_names includes roleA, so appB should be reachable
-        result = gdf_module.FilterModule.add_domain_if_group({}, 'appB', 'domainB', ['roleA'])
-        self.assertEqual(result, {'appB': 'domainB'})
-
-    def test_multi_level_dependency_application_id(self):
-        # roleX -> roleY -> roleZ; roleZ id is 'appZ'
-        self.write_role('roleX', ['roleY'], 'appX')
-        self.write_role('roleY', ['roleZ'], 'appY')
-        self.write_role('roleZ', [], 'appZ')
-        # Starting from roleX, appZ reachable
-        result = gdf_module.FilterModule.add_domain_if_group({}, 'appZ', 'domainZ', ['roleX'])
-        self.assertEqual(result, {'appZ': 'domainZ'})
-
-    def test_domain_key_for_parent_role(self):
-        # roleParent has app 'appP', and depends on roleChild('appC')
-        self.write_role('roleParent', ['roleChild'], 'appP')
-        self.write_role('roleChild', [], 'appC')
-        # Even appP reachable via deps of roleParent (including itself)
-        result = gdf_module.FilterModule.add_domain_if_group({}, 'appP', 'domainP', ['roleParent'])
-        self.assertEqual(result, {'appP': 'domainP'})
-
-    def test_no_inclusion_for_unrelated(self):
-        # Unrelated roles
-        self.write_role('roleC', ['roleD'], 'appC')
-        self.write_role('roleD', [], 'appD')
-        # group_names does not include 'roleC' or 'roleD'
-        result = gdf_module.FilterModule.add_domain_if_group({}, 'appC', 'domainC', ['otherRole'])
-        self.assertEqual(result, {})
-
-if __name__ == '__main__':
-    unittest.main()
diff --git a/tests/unit/test_load_configuration.py b/tests/unit/test_load_configuration.py
new file mode 100644
index 00000000..b1515d66
--- /dev/null
+++ b/tests/unit/test_load_configuration.py
@@ -0,0 +1,118 @@
+import os
+import sys
+import unittest
+from unittest.mock import patch, mock_open
+from ansible.errors import AnsibleFilterError
+
+# make sure our plugin is on PYTHONPATH
+root = os.path.abspath(os.path.join(os.path.dirname(__file__), '../../filter_plugins'))
+sys.path.insert(0, root)
+
+import load_configuration
+from load_configuration import FilterModule, _cfg_cache
+
+class TestLoadConfigurationFilter(unittest.TestCase):
+    def setUp(self):
+        _cfg_cache.clear()
+        self.f = FilterModule().filters()['load_configuration']
+        self.app = 'html_server'
+        self.nested_cfg = {
+            'html_server': {
+                'features': {'matomo': True},
+                'domains': {'canonical': ['html.example.com']}
+            }
+        }
+        self.flat_cfg = {
+            'features': {'matomo': False},
+            'domains': {'canonical': ['flat.example.com']}
+        }
+
+    def test_invalid_key(self):
+        with self.assertRaises(AnsibleFilterError):
+            self.f(self.app, None)
+
+    @patch('load_configuration.os.path.isdir', return_value=False)
+    def test_no_roles_dir(self, _):
+        with self.assertRaises(AnsibleFilterError):
+            self.f(self.app, 'features.matomo')
+
+    @patch('load_configuration.os.listdir', return_value=['r1'])
+    @patch('load_configuration.os.path.isdir', return_value=True)
+    @patch('load_configuration.os.path.exists', return_value=False)
+    def test_no_matching_role(self, *_):
+        self.assertIsNone(self.f(self.app, 'features.matomo'))
+
+    @patch('load_configuration.os.listdir', return_value=['r1'])
+    @patch('load_configuration.os.path.isdir', return_value=True)
+    @patch('load_configuration.os.path.exists')
+    @patch('load_configuration.open', new_callable=mock_open)
+    @patch('load_configuration.yaml.safe_load')
+    def test_primary_missing_conf(self, mock_yaml, mock_file, mock_exists, *_):
+        mock_exists.side_effect = lambda p: p.endswith('vars/main.yml')
+        mock_yaml.return_value = {'application_id': self.app}
+        with self.assertRaises(AnsibleFilterError):
+            self.f(self.app, 'features.matomo')
+
+    @patch('load_configuration.os.listdir', return_value=['r1'])
+    @patch('load_configuration.os.path.isdir', return_value=True)
+    @patch('load_configuration.os.path.exists')
+    @patch('load_configuration.open', new_callable=mock_open)
+    @patch('load_configuration.yaml.safe_load')
+    def test_primary_and_cache(self, mock_yaml, mock_file, mock_exists, *_):
+        mock_exists.side_effect = lambda p: p.endswith('vars/main.yml') or p.endswith('vars/configuration.yml')
+        mock_yaml.side_effect = [
+            {'application_id': self.app},  # main.yml
+            self.nested_cfg              # configuration.yml
+        ]
+        # first load
+        self.assertTrue(self.f(self.app, 'features.matomo'))
+        self.assertIn(self.app, _cfg_cache)
+        mock_yaml.reset_mock()
+        # from cache
+        self.assertEqual(self.f(self.app, 'domains.canonical'),
+                         ['html.example.com'])
+        mock_yaml.assert_not_called()
+
+    @patch('load_configuration.os.listdir', return_value=['r1'])
+    @patch('load_configuration.os.path.isdir', return_value=True)
+    @patch('load_configuration.os.path.exists', return_value=True)
+    @patch('load_configuration.open', mock_open(read_data="html_server: {}"))
+    @patch('load_configuration.yaml.safe_load', return_value={'html_server': {}})
+    def test_key_not_found_after_load(self, *_):
+        with self.assertRaises(AnsibleFilterError):
+            self.f(self.app, 'does.not.exist')
+
+    @patch('load_configuration.os.listdir', return_value=['r2'])
+    @patch('load_configuration.os.path.isdir', return_value=True)
+    @patch('load_configuration.os.path.exists')
+    @patch('load_configuration.open', new_callable=mock_open)
+    @patch('load_configuration.yaml.safe_load')
+    def test_fallback_nested(self, mock_yaml, mock_file, mock_exists, *_):
+        mock_exists.side_effect = lambda p: p.endswith('vars/configuration.yml')
+        mock_yaml.return_value = self.nested_cfg
+        # nested fallback must work
+        self.assertTrue(self.f(self.app, 'features.matomo'))
+        self.assertEqual(self.f(self.app, 'domains.canonical'),
+                         ['html.example.com'])
+
+    @patch('load_configuration.os.listdir', return_value=['r4'])
+    @patch('load_configuration.os.path.isdir', return_value=True)
+    @patch('load_configuration.os.path.exists')
+    @patch('load_configuration.open', new_callable=mock_open)
+    @patch('load_configuration.yaml.safe_load')
+    def test_fallback_with_indexed_key(self, mock_yaml, mock_file, mock_exists, *_):
+        # Testing with an indexed key like domains.canonical[0]
+        mock_exists.side_effect = lambda p: p.endswith('vars/configuration.yml')
+        mock_yaml.return_value = {
+            'file-server': {
+                'domains': {
+                    'canonical': ['files.example.com', 'extra.example.com']
+                }
+            }
+        }
+        # should get the first element of the canonical domains list
+        self.assertEqual(self.f('file-server', 'domains.canonical[0]'),
+                         'files.example.com')
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/tests/unit/test_merge_mapping.py b/tests/unit/test_merge_mapping.py
new file mode 100644
index 00000000..7d7d133c
--- /dev/null
+++ b/tests/unit/test_merge_mapping.py
@@ -0,0 +1,45 @@
+import unittest
+from filter_plugins.merge_mapping import merge_mapping
+from ansible.errors import AnsibleFilterError
+
+class TestMergeMappingFilter(unittest.TestCase):
+    def test_basic_merge_overwrites_and_adds(self):
+        list1 = [
+            {'source': 'a', 'target': 1},
+            {'source': 'b', 'target': 2},
+        ]
+        list2 = [
+            {'source': 'b', 'target': 3},
+            {'source': 'c', 'target': 4},
+        ]
+        result = merge_mapping(list1, list2, 'source')
+        result_dict = {item['source']: item['target'] for item in result}
+        self.assertEqual(result_dict, {'a': 1, 'b': 3, 'c': 4})
+
+    def test_merge_preserves_and_overwrites_fields(self):
+        list1 = [{'source': 'x', 'value': 100, 'flag': True}]
+        list2 = [{'source': 'x', 'value': 200, 'note': 'updated'}]
+        result = merge_mapping(list1, list2, 'source')
+        self.assertEqual(len(result), 1)
+        merged = result[0]
+        self.assertEqual(merged['value'], 200)
+        self.assertTrue(merged['flag'])
+        self.assertEqual(merged['note'], 'updated')
+
+    def test_empty_lists_return_empty(self):
+        self.assertEqual(merge_mapping([], [], 'source'), [])
+
+    def test_missing_key_raises_error(self):
+        list1 = [{'target': 'no_source'}]
+        list2 = []
+        with self.assertRaises(AnsibleFilterError):
+            merge_mapping(list1, list2, 'source')
+
+    def test_non_list_inputs_raise_error(self):
+        with self.assertRaises(AnsibleFilterError):
+            merge_mapping("not a list", [], 'source')
+        with self.assertRaises(AnsibleFilterError):
+            merge_mapping([], "not a list", 'source')
+
+if __name__ == '__main__':
+    unittest.main()
\ No newline at end of file
diff --git a/tests/unit/test_redirect_filters.py b/tests/unit/test_redirect_filters.py
deleted file mode 100644
index aa87fbd1..00000000
--- a/tests/unit/test_redirect_filters.py
+++ /dev/null
@@ -1,57 +0,0 @@
-import os
-import sys
-import unittest
-
-sys.path.insert(
-    0,
-    os.path.abspath(
-        os.path.join(os.path.dirname(__file__), "../../")
-    ),
-)
-
-from filter_plugins.redirect_filters import FilterModule
-
-
-class TestAddRedirectIfGroup(unittest.TestCase):
-    """Unit-tests for the add_redirect_if_group filter."""
-
-    def setUp(self):
-        # Obtain the callable once for reuse
-        self.add_redirect = FilterModule().filters()["add_redirect_if_group"]
-
-    def test_appends_redirect_when_group_present(self):
-        original = [{"source": "a", "target": "b"}]
-        result = self.add_redirect(
-            original,
-            group="lam",
-            source="ldap.example.com",
-            target="lam.example.com",
-            group_names=["lam", "other"],
-        )
-
-        # Original list must stay unchanged
-        self.assertEqual(len(original), 1)
-        # Result list must contain the extra entry
-        self.assertEqual(len(result), 2)
-        self.assertIn(
-            {"source": "ldap.example.com", "target": "lam.example.com"}, result
-        )
-
-    def test_keeps_list_unchanged_when_group_absent(self):
-        original = [{"source": "a", "target": "b"}]
-        result = self.add_redirect(
-            original,
-            group="lam",
-            source="ldap.example.com",
-            target="lam.example.com",
-            group_names=["unrelated"],
-        )
-
-        # No new entries
-        self.assertEqual(result, original)
-        # But ensure a new list object was returned (no in-place mutation)
-        self.assertIsNot(result, original)
-
-
-if __name__ == "__main__":
-    unittest.main()