feat(filters): enforce safe Node.js heap sizing via reusable filter

- Add node_autosize filter (node_max_old_space_size) using get_app_conf
- Raise error when mem_limit < min_mb to prevent OOM-kill misconfigurations
- Wire Whiteboard NODE_OPTIONS and increase mem_limit to 1g; set cpus=1
- Refactor PeerTube to use the same filter; simplify vars
- Add unit tests; keep integration filters usage green

Context: https://chatgpt.com/share/690e0499-6a94-800f-b8ed-2c5124690103

filter_plugins/node_autosize.py

@@ -0,0 +1,141 @@
+# filter_plugins/node_autosize.py
+# Reuse app config to derive sensible Node.js heap sizes for containers.
+#
+# Usage example (Jinja):
+#   {{ applications | node_max_old_space_size('web-app-nextcloud', 'whiteboard') }}
+#
+# Heuristics (defaults):
+#   - candidate = 35% of mem_limit
+#   - min       = 768 MB (required minimum)
+#   - cap       = min(3072 MB, 60% of mem_limit)
+#
+# NEW: If mem_limit (container cgroup RAM) is smaller than min_mb, we raise an
+# exception — to prevent a misconfiguration where Node's heap could exceed the cgroup
+# and be OOM-killed.
+
+from __future__ import annotations
+import re
+from ansible.errors import AnsibleFilterError
+
+# Import the shared config resolver from module_utils
+try:
+    from module_utils.config_utils import get_app_conf, AppConfigKeyError
+except Exception as e:
+    raise AnsibleFilterError(
+        f"Failed to import get_app_conf from module_utils.config_utils: {e}"
+    )
+
+_SIZE_RE = re.compile(r"^\s*(\d+(?:\.\d+)?)\s*([kmgtp]?i?b?)?\s*$", re.IGNORECASE)
+_MULT = {
+    "": 1,
+    "b": 1,
+    "k": 10**3, "kb": 10**3,
+    "m": 10**6, "mb": 10**6,
+    "g": 10**9, "gb": 10**9,
+    "t": 10**12, "tb": 10**12,
+    "p": 10**15, "pb": 10**15,
+    "kib": 1024,
+    "mib": 1024**2,
+    "gib": 1024**3,
+    "tib": 1024**4,
+    "pib": 1024**5,
+}
+
+
+def _to_bytes(val):
+    """Convert numeric or string memory limits (e.g. '512m', '2GiB') to bytes."""
+    if val is None or val == "":
+        return None
+    if isinstance(val, (int, float)):
+        return int(val)
+    if not isinstance(val, str):
+        raise AnsibleFilterError(f"Unsupported mem_limit type: {type(val).__name__}")
+    m = _SIZE_RE.match(val)
+    if not m:
+        raise AnsibleFilterError(f"Unrecognized mem_limit string: {val!r}")
+    num = float(m.group(1))
+    unit = (m.group(2) or "").lower()
+    if unit not in _MULT:
+        raise AnsibleFilterError(f"Unknown unit in mem_limit: {unit!r}")
+    return int(num * _MULT[unit])
+
+
+def _mb(bytes_val: int) -> int:
+    """Return decimal MB (10^6) as integer — Node expects MB units."""
+    return int(round(bytes_val / 10**6))
+
+
+def _compute_old_space_mb(
+    total_mb: int, pct: float, min_mb: int, hardcap_mb: int, safety_cap_pct: float
+) -> int:
+    """
+    Compute Node.js old-space heap (MB) with safe minimum and cap handling.
+
+    NOTE: The calling function ensures total_mb >= min_mb; here we only
+    apply the sizing heuristics and caps.
+    """
+    candidate = int(total_mb * float(pct))
+    safety_cap = int(total_mb * float(safety_cap_pct))
+    final_cap = min(int(hardcap_mb), safety_cap)
+
+    # Enforce minimum first; only apply cap if it's above the minimum
+    candidate = max(candidate, int(min_mb))
+    if final_cap >= int(min_mb):
+        candidate = min(candidate, final_cap)
+
+    # Never below a tiny hard floor
+    return max(candidate, 128)
+
+
+def node_max_old_space_size(
+    applications: dict,
+    application_id: str,
+    service_name: str,
+    pct: float = 0.35,
+    min_mb: int = 768,
+    hardcap_mb: int = 3072,
+    safety_cap_pct: float = 0.60,
+) -> int:
+    """
+    Derive Node.js --max-old-space-size (MB) from the service's mem_limit in app config.
+
+    Looks up: docker.services.<service_name>.mem_limit for the given application_id.
+
+    Raises:
+        AnsibleFilterError if mem_limit is missing/invalid OR if mem_limit (MB) < min_mb.
+    """
+    try:
+        mem_limit = get_app_conf(
+            applications=applications,
+            application_id=application_id,
+            config_path=f"docker.services.{service_name}.mem_limit",
+            strict=True,
+            default=None,
+        )
+    except AppConfigKeyError as e:
+        raise AnsibleFilterError(str(e))
+
+    if mem_limit in (None, False, ""):
+        raise AnsibleFilterError(
+            f"mem_limit not set for application '{application_id}', service '{service_name}'"
+        )
+
+    total_bytes = _to_bytes(mem_limit)
+    total_mb = _mb(total_bytes)
+
+    # NEW: guardrail — refuse to size a heap larger than the cgroup limit
+    if total_mb < int(min_mb):
+        raise AnsibleFilterError(
+            f"mem_limit ({total_mb} MB) is below the required minimum heap ({int(min_mb)} MB) "
+            f"for application '{application_id}', service '{service_name}'. "
+            f"Increase mem_limit or lower min_mb."
+        )
+
+    return _compute_old_space_mb(total_mb, pct, min_mb, hardcap_mb, safety_cap_pct)
+
+
+class FilterModule(object):
+    def filters(self):
+        return {
+            "node_max_old_space_size": node_max_old_space_size,
+        }