landing: central container memory/load stats for all three sites

Collect RSS groups, top processes, and loadavg from inside each podman
container (not host /proc), merge into performance.memory, show compact
labels with cgroup limits and byte tooltips, and cover this in the test suite.

scripts/taler-landing/merge_resources.py

@@ -0,0 +1,106 @@
+#!/usr/bin/env python3
+"""Merge container resource snapshot into landing stats.json performance block.
+
+Usage:
+  merge_resources.py STATS.json RESOURCES.json [-o OUT.json]
+
+RESOURCES shape (from mem_snapshot_emit / collect_container_resources.sh):
+  { "ok": true, "loadavg": "0.1,0.2,0.3", "memory": { ... } }
+"""
+from __future__ import annotations
+
+import argparse
+import json
+import os
+import sys
+from pathlib import Path
+from typing import Any, Dict
+
+
+def compact_memory(mem: Dict[str, Any]) -> Dict[str, Any]:
+    """Ensure human labels + short top cmd for UI width."""
+    if not isinstance(mem, dict):
+        return mem
+    # Prefer explicit label (with limit); else human
+    if not mem.get("container_rss_label"):
+        h = mem.get("container_rss_human") or "—"
+        lim = mem.get("cgroup_limit_human")
+        if lim:
+            mem["container_rss_label"] = f"{h} / {lim}"
+        else:
+            mem["container_rss_label"] = h
+    tops = mem.get("top")
+    if isinstance(tops, list):
+        for t in tops:
+            if not isinstance(t, dict):
+                continue
+            cmd = str(t.get("cmd") or "")
+            if len(cmd) > 72:
+                t["cmd_full"] = cmd
+                t["cmd"] = cmd[:69] + "…"
+            # ensure human present
+            if not t.get("rss_human") and t.get("rss_bytes") is not None:
+                try:
+                    b = int(t["rss_bytes"])
+                    if b < 1024:
+                        t["rss_human"] = f"{b} B"
+                    elif b < 1048576:
+                        t["rss_human"] = f"{b/1024:.1f} KiB"
+                    elif b < 1073741824:
+                        t["rss_human"] = f"{b/1048576:.1f} MiB"
+                    else:
+                        t["rss_human"] = f"{b/1073741824:.2f} GiB"
+                except Exception:
+                    pass
+    return mem
+
+
+def merge(stats: Dict[str, Any], resources: Dict[str, Any]) -> Dict[str, Any]:
+    perf = stats.setdefault("performance", {})
+    if not isinstance(perf, dict):
+        perf = {}
+        stats["performance"] = perf
+
+    if resources.get("loadavg"):
+        perf["loadavg"] = resources["loadavg"]
+        perf["loadavg_source"] = "container"
+
+    mem = resources.get("memory")
+    if isinstance(mem, dict) and mem:
+        perf["memory"] = compact_memory(dict(mem))
+        perf["memory"]["source"] = resources.get("source") or "mem-snapshot"
+    return stats
+
+
+def main() -> int:
+    ap = argparse.ArgumentParser()
+    ap.add_argument("stats")
+    ap.add_argument("resources")
+    ap.add_argument("-o", "--out", default="")
+    args = ap.parse_args()
+
+    stats = json.loads(Path(args.stats).read_text(encoding="utf-8"))
+    resources = json.loads(Path(args.resources).read_text(encoding="utf-8"))
+    if not isinstance(stats, dict) or not stats.get("ok"):
+        print("skip: stats not ok", file=sys.stderr)
+        return 1
+    if not isinstance(resources, dict) or resources.get("ok") is False:
+        print("skip: resources not ok", file=sys.stderr)
+        return 1
+
+    merge(stats, resources)
+    out = Path(args.out) if args.out else Path(args.stats)
+    tmp = out.with_suffix(out.suffix + f".tmp.{os.getpid()}")
+    tmp.write_text(json.dumps(stats, indent=2, ensure_ascii=False) + "\n", encoding="utf-8")
+    tmp.replace(out)
+    mem = (stats.get("performance") or {}).get("memory") or {}
+    print(
+        f"merged memory container={mem.get('container_rss_human')} "
+        f"pg={mem.get('postgres_rss_human')} loadavg={stats.get('performance', {}).get('loadavg')}",
+        file=sys.stderr,
+    )
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())