feat(filters): add active_docker_container_count filter and use it for fair resource splits

Compute per-container CPU/RAM shares based on active services (web-/svc-*, enabled=true or undefined). Cast host facts to numbers, add safe min=1, and output compose-ready values. Include robust unit test.

Also: include resource.yml.j2 in base template and minor formatting tidy-up.

https://chatgpt.com/share/68d2d96c-9bf4-800f-bbec-d4f2c0051c06

filter_plugins/active_docker.py

@@ -0,0 +1,79 @@
+# -*- coding: utf-8 -*-
+"""
+Ansible filter to count active docker services for current host.
+
+Active means:
+- application key is in group_names
+- application key matches prefix regex (default: ^(web-|svc-).* )
+- under applications[app]['docker']['services'] each service is counted if:
+  - 'enabled' is True, OR
+  - 'enabled' is missing/undefined  (treated as active)
+
+Returns an integer. If ensure_min_one=True, returns at least 1.
+"""
+
+import re
+from typing import Any, Dict, Mapping, Iterable
+
+
+def _is_mapping(x: Any) -> bool:
+    # be liberal: Mapping covers dict-like; fallback to dict check
+    try:
+        return isinstance(x, Mapping)
+    except Exception:
+        return isinstance(x, dict)
+
+
+def active_docker_container_count(applications: Mapping[str, Any],
+                                  group_names: Iterable[str],
+                                  prefix_regex: str = r'^(web-|svc-).*',
+                                  ensure_min_one: bool = False) -> int:
+    if not _is_mapping(applications):
+        return 1 if ensure_min_one else 0
+
+    group_set = set(group_names or [])
+    try:
+        pattern = re.compile(prefix_regex)
+    except re.error:
+        pattern = re.compile(r'^(web-|svc-).*')  # fallback
+
+    count = 0
+
+    for app_key, app_val in applications.items():
+        # host selection + name prefix
+        if app_key not in group_set:
+            continue
+        if not pattern.match(str(app_key)):
+            continue
+
+        docker = app_val.get('docker') if _is_mapping(app_val) else None
+        services = docker.get('services') if _is_mapping(docker) else None
+        if not _is_mapping(services):
+            # sometimes roles define a single service name string; ignore
+            continue
+
+        for _svc_name, svc_cfg in services.items():
+            if not _is_mapping(svc_cfg):
+                # allow shorthand like: service: {} or image string -> counts as enabled
+                count += 1
+                continue
+            enabled = svc_cfg.get('enabled', True)
+            if isinstance(enabled, bool):
+                if enabled:
+                    count += 1
+            else:
+                # non-bool enabled -> treat "truthy" as enabled
+                if bool(enabled):
+                    count += 1
+
+    if ensure_min_one and count < 1:
+        return 1
+    return count
+
+
+class FilterModule(object):
+    def filters(self):
+        return {
+            # usage: {{ applications | active_docker_container_count(group_names) }}
+            'active_docker_container_count': active_docker_container_count,
+        }