Use coordinated docs port with conflict checks and deployment-independent cache keys

scripts/deploy.py

@@ -5,6 +5,7 @@ import os
 from pathlib import Path
 import re
 import shutil
+import socket
 import subprocess
 import urllib.request
 from ci import APP, ROOT, fingerprint, run
@@ -29,6 +30,25 @@ def compose(release: Path, *args: str) -> None:
         "--env-file", str(release / "release.env"), "-f", str(release / "compose.yml"), *args)
 
 
+def check_port(port: int) -> None:
+    # An existing container belonging to this Compose service may retain its port.
+    own = run("docker", "ps", "-q", "--filter", f"label=com.docker.compose.project={APP}",
+              "--filter", "label=com.docker.compose.service=docs", capture=True)
+    if own:
+        for container in own.splitlines():
+            details = json.loads(run("docker", "inspect", container, capture=True))[0]
+            ports = details["NetworkSettings"]["Ports"].get("3000/tcp") or []
+            if any(item["HostPort"] == str(port) for item in ports):
+                print(f"Port {port} belongs to the current Tabularium service", flush=True)
+                return
+    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as probe:
+        try:
+            probe.bind(("0.0.0.0", port))
+        except OSError as error:
+            raise RuntimeError(f"Port {port} is already occupied; no service was changed") from error
+    print(f"Port {port} is available", flush=True)
+
+
 def main() -> None:
     if os.geteuid() != 0:
         raise RuntimeError("Deployment requires root on ces-control")
@@ -48,13 +68,14 @@ def main() -> None:
         run("docker", "image", "inspect", actual, capture=True)
         CONFIG.parent.mkdir(parents=True, exist_ok=True)
         if not CONFIG.exists():
-            CONFIG.write_text("TABULARIUM_BIND=0.0.0.0\nTABULARIUM_PORT=18132\n")
+            CONFIG.write_text("TABULARIUM_BIND=0.0.0.0\nTABULARIUM_PORT=18135\n")
             CONFIG.chmod(0o600)
         settings = dict(line.split("=", 1) for line in CONFIG.read_text().splitlines()
                         if line and not line.startswith("#"))
-        port = int(settings.get("TABULARIUM_PORT", "18132"))
+        port = int(settings.get("TABULARIUM_PORT", "18135"))
         if not 1024 <= port <= 65535:
             raise ValueError("Invalid port")
+        check_port(port)
         current = DEPLOY_ROOT / "current"
         previous = current.resolve() if current.is_symlink() else None
         release = DEPLOY_ROOT / "releases" / sha