Use the autoupdate label for image updates

playbooks/filesystem/common/usr/local/sbin/pod-service-auto-update

@@ -14,28 +14,50 @@ import getpass
 import json
 import subprocess
 
+
+def podman_ps():
+    out = subprocess.run(["podman", "ps", "--format", "json"], capture_output=True, check=True)
+    return json.loads(out.stdout)
+
+
+def podman_image_inspect(image):
+    out = subprocess.run(["podman", "image", "inspect", "--format", "json", image],
+                         capture_output=True, check=True)
+    inspect = json.loads(out.stdout)
+    assert inspect
+    if len(inspect) > 1:
+        raise ValueError("podman image inspect returned multiple entries")
+    return inspect[0]
+
+def podman_pull(image):
+    subprocess.run(["podman", "pull", image], capture_output=True, check=True)
+
 if __name__ == "__main__":
-    out = subprocess.run(["podman", "images", "--format", "json"], capture_output=True, check=True)
-    images = json.loads(out.stdout)
+    containers = podman_ps()
+
+    images = set()
+    for container in containers:
+        labels = container.get("Labels", None)
+        if labels is None:
+            continue
+        autoupdate = labels.get("io.containers.autoupdate", None)
+        if (autoupdate is None) or (autoupdate == "disabled"):
+            continue
+        if autoupdate != "image":
+            raise ValueError(f"unrecognised autopdate label: {autoupdate}")
+        images.add(container["Image"])
 
     updated = []
     for image in images:
-        if not image["Names"]:
-            continue
-        if len(image["Names"]) > 1:
-            raise ValueError(f"Multiple names available for image: {image['Names']}")
-        name = image["Names"][0]
+        inspect = podman_image_inspect(image)
+        original_digest = inspect["Digest"]
 
-        subprocess.run(["podman", "pull", name], capture_output=True, check=True)
+        podman_pull(image)
 
-        out = subprocess.run(["podman", "inspect", "--format", "json", name],
-                             capture_output=True, check=True)
-        inspect = json.loads(out.stdout)
-        assert inspect
-        if len(inspect) > 1:
-            raise ValueError("Podman inspect returned multiple entries")
+        inspect = podman_image_inspect(image)
+        new_digest = inspect["Digest"]
 
-        if inspect[0]["Digest"] != image["Digest"]:
+        if new_digest != original_digest:
             updated.append(name)
 
     if updated: