agent image: add sqlite3 + sync v1.3 (SQLite file backups, chunked upload, metrics)

- sqlite3 in the image so the agent can back up SQLite files (Vaultwarden etc.) via .dump.
- Sync backhaul-agent.py to v1.3: sqlite engine (sqlite:<path> target), chunked upload
  (large dumps past the CDN cap), live metrics, self-update UA fix.

backhaul-agent.py

@@ -22,18 +22,27 @@ import subprocess
 import sys
 import urllib.request
 
-VERSION = "1.0"
+VERSION = "1.3"
 RESULT_FILE = os.path.join(os.path.dirname(os.path.abspath(__file__)), ".dump-result.json")
 
 
 def targets():
-    """Parse BACKHAUL_TARGETS into dicts. Each: engine:host:port:db:user:pass."""
+    """Parse BACKHAUL_TARGETS into dicts. A networked DB is engine:host:port:db:user:pass;
+    a SQLite file is sqlite:<path> (a file bind-mounted into the agent, not a server)."""
     out = []
     for spec in os.environ.get("BACKHAUL_TARGETS", "").split(","):
         spec = spec.strip()
         if not spec:
             continue
         parts = spec.split(":")
+        if parts[0] == "sqlite":
+            path = ":".join(parts[1:]).strip()      # rejoin in case the path holds a ':'
+            if not path:
+                print(f"skipping sqlite target without a path: {spec}", file=sys.stderr)
+                continue
+            out.append({"engine": "sqlite", "path": path,
+                        "name": f"sqlite/{os.path.basename(path)}"})
+            continue
         if len(parts) < 6:
             print(f"skipping malformed target: {spec}", file=sys.stderr)
             continue
@@ -47,6 +56,10 @@ def targets():
 def db_version(t):
     """Fetch the engine version string so the app can pick a matching restore image."""
     try:
+        if t["engine"] == "sqlite":
+            out = subprocess.run(("sqlite3", "--version"),
+                                 capture_output=True, text=True, timeout=15).stdout
+            return "SQLite " + ((out.strip().split(" ")[0]) or "3")
         if t["engine"] == "postgres":
             env = dict(os.environ, PGPASSWORD=t["pw"])
             out = subprocess.run(("psql", "-h", t["host"], "-p", t["port"], "-U", t["user"],
@@ -65,8 +78,79 @@ def db_version(t):
     return t["engine"]
 
 
+def db_stats(t):
+    """Read-only live metrics for the dashboard's 'nerd stats' — size, tables, rows, index
+    footprint, connections, cache-hit ratio, the biggest tables, server version + uptime.
+    Best-effort: any failure returns None and never disturbs the heartbeat. Postgres only."""
+    if t["engine"] == "sqlite":
+        return _sqlite_stats(t)
+    if t["engine"] != "postgres":
+        return None
+    env = dict(os.environ, PGPASSWORD=t["pw"])
+
+    def q(sql):
+        r = subprocess.run(("psql", "-h", t["host"], "-p", t["port"], "-U", t["user"],
+                            "-d", t["db"], "-tAc", sql),
+                           capture_output=True, text=True, timeout=30, env=env)
+        return r.stdout.strip()
+
+    try:
+        top = q("SELECT COALESCE(json_agg(x),'[]') FROM (SELECT relname AS name, "
+                "pg_total_relation_size(relid) AS bytes, n_live_tup AS rows "
+                "FROM pg_stat_user_tables ORDER BY pg_total_relation_size(relid) DESC "
+                "LIMIT 10) x")
+        hit = q("SELECT round(100.0*sum(blks_hit)/NULLIF(sum(blks_hit)+sum(blks_read),0),2) "
+                "FROM pg_stat_database WHERE datname=current_database()")
+        up = q("SELECT EXTRACT(EPOCH FROM (now()-pg_postmaster_start_time()))::bigint")
+        return {
+            "size_bytes": int(q("SELECT pg_database_size(current_database())") or 0),
+            "tables": int(q("SELECT count(*) FROM pg_stat_user_tables") or 0),
+            "rows_est": int(float(q("SELECT COALESCE(SUM(n_live_tup),0) "
+                                    "FROM pg_stat_user_tables") or 0)),
+            "index_bytes": int(q("SELECT COALESCE(SUM(pg_indexes_size(relid)),0) "
+                                 "FROM pg_stat_user_tables") or 0),
+            "connections": int(q("SELECT count(*) FROM pg_stat_activity "
+                                 "WHERE datname=current_database()") or 0),
+            "cache_hit_pct": float(hit) if hit else None,
+            "server_version": q("SHOW server_version"),
+            "uptime_s": int(up) if up else None,
+            "top_tables": json.loads(top or "[]"),
+        }
+    except Exception:
+        return None
+
+
+def _sqlite_stats(t):
+    """Live metrics for a SQLite file: file size, table count, row totals, largest tables."""
+    def q(sql):
+        r = subprocess.run(("sqlite3", t["path"], sql),
+                           capture_output=True, text=True, timeout=30)
+        return r.stdout.strip()
+    try:
+        names = [n for n in q("SELECT name FROM sqlite_master WHERE type='table' "
+                              "AND name NOT LIKE 'sqlite_%' ORDER BY name").splitlines() if n]
+        top = []
+        rows = 0
+        for n in names:
+            c = int(q(f'SELECT count(*) FROM "{n}"') or 0)
+            rows += c
+            top.append({"name": n, "bytes": 0, "rows": c})
+        top.sort(key=lambda x: x["rows"], reverse=True)
+        size = os.path.getsize(t["path"]) if os.path.exists(t["path"]) else 0
+        return {"size_bytes": size, "tables": len(names), "rows_est": rows,
+                "index_bytes": 0, "connections": 0, "cache_hit_pct": None,
+                "server_version": "SQLite " + q("SELECT sqlite_version()"),
+                "uptime_s": None, "top_tables": top[:10]}
+    except Exception:
+        return None
+
+
 def dump_cmd(t):
     """The dump command + environment for an engine. Streams compressed to stdout."""
+    if t["engine"] == "sqlite":
+        # `.dump` runs in a read transaction → a consistent SQL snapshot even under writes.
+        # The file (and its -wal/-shm) must be readable in the agent container (bind-mount).
+        return (("sqlite3", t["path"], ".dump"), dict(os.environ))
     if t["engine"] == "postgres":
         env = dict(os.environ, PGPASSWORD=t["pw"])
         # custom format is already compressed and is what pg_restore wants
@@ -83,22 +167,60 @@ def dump_cmd(t):
     raise ValueError(f"unknown engine {t['engine']}")
 
 
+UPLOAD_CHUNK = 64 * 1024 * 1024  # keep each request well under Cloudflare's 100 MB body cap
+
+
+def _post_chunk(url, token, name, meta, upload_id, index, final, data):
+    """POST one slice of a dump. Each request has a normal Content-Length under the CDN limit,
+    so this works over the public HTTPS URL from any server, not just co-located ones."""
+    req = urllib.request.Request(
+        url.rstrip("/") + "/api/dump", data=bytes(data),
+        headers={"X-Agent-Token": token, "X-DB-Name": name, "X-DB-Meta": meta,
+                 "X-Upload-Id": upload_id, "X-Chunk-Index": str(index),
+                 "X-Chunk-Final": "1" if final else "0",
+                 "Content-Type": "application/octet-stream",
+                 "User-Agent": f"backhaul-agent/{VERSION}"})
+    with urllib.request.urlopen(req, timeout=3600) as resp:
+        return resp.status == 200
+
+
 def run_dump(t, url, token):
-    """Stream a dump of one target straight to the app's ingest endpoint — never buffer the
-    whole dump in memory or a temp file."""
+    """Stream a dump home in <100 MB slices so it passes the CDN's upload limit from any
+    server; the app reassembles by upload id and finalizes on the last slice. The dump is never
+    fully buffered — only one slice is held at a time."""
     cmd, env = dump_cmd(t)
     meta = json.dumps({"engine": t["engine"], "version": db_version(t)})
-    req = urllib.request.Request(
-        url.rstrip("/") + "/api/dump",
-        headers={"X-Agent-Token": token, "X-DB-Name": t["name"],
-                 "X-DB-Meta": meta, "Content-Type": "application/octet-stream",
-                 "Transfer-Encoding": "chunked", "User-Agent": f"backhaul-agent/{VERSION}"})
+    upload_id = os.urandom(8).hex()
     proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, env=env)
-    # feed the dump process's stdout straight into the HTTP request body
-    req.data = iter(lambda: proc.stdout.read(1 << 20), b"")
-    with urllib.request.urlopen(req, timeout=3600) as resp:
+    buf = bytearray()
+    index = 0
+    ok = True
+    try:
+        while True:
+            b = proc.stdout.read(1 << 20)
+            if not b:
+                break
+            buf += b
+            while len(buf) >= UPLOAD_CHUNK:
+                if not _post_chunk(url, token, t["name"], meta, upload_id, index, False,
+                                   buf[:UPLOAD_CHUNK]):
+                    ok = False
+                    break
+                del buf[:UPLOAD_CHUNK]
+                index += 1
+            if not ok:
+                break
         proc.wait()
-        return {"name": t["name"], "ok": resp.status == 200 and proc.returncode == 0}
+        if ok:                          # final slice finalizes the backup (even if empty)
+            ok = _post_chunk(url, token, t["name"], meta, upload_id, index, True, bytes(buf))
+    except Exception as e:
+        print("dump upload failed:", e, file=sys.stderr)
+        ok = False
+    finally:
+        if proc.poll() is None:
+            proc.kill()
+            proc.wait()
+    return {"name": t["name"], "ok": ok and proc.returncode == 0}
 
 
 def maybe_self_update(answer, url, token):
@@ -110,8 +232,10 @@ def maybe_self_update(answer, url, token):
         return
     me = os.path.abspath(__file__)
     try:
-        req = urllib.request.Request(url.rstrip("/") + "/api/agent-script",
-                                     headers={"X-Agent-Token": token})
+        req = urllib.request.Request(
+            url.rstrip("/") + "/api/agent-script",
+            headers={"X-Agent-Token": token,
+                     "User-Agent": f"backhaul-agent/{VERSION}"})  # else Cloudflare 403s urllib
         with urllib.request.urlopen(req, timeout=30) as r:
             source = r.read()
         text = source.decode()
@@ -131,9 +255,14 @@ def maybe_self_update(answer, url, token):
 def checkin(url, token, tgts, pending):
     """POST the heartbeat: which DBs we see + any finished dump result. The reply tells us
     what to do next and the latest agent version."""
+    stats = {}
+    for t in tgts:
+        s = db_stats(t)
+        if s:
+            stats[t["name"]] = s
     body = json.dumps({"agent_version": VERSION,
                        "databases": [{"name": t["name"], "engine": t["engine"]} for t in tgts],
-                       "results": pending}).encode()
+                       "results": pending, "stats": stats}).encode()
     req = urllib.request.Request(url.rstrip("/") + "/api/checkin", data=body,
                                  headers={"X-Agent-Token": token,
                                           "Content-Type": "application/json",