Extracted platform config to platforms.json and automated image updates

.github/workflows/build-base-images.yml

@@ -1,7 +1,9 @@
 name: Build base images
 
 on:
-  workflow_dispatch:
+  schedule:
+    - cron: "0 0 * * 0" # Every Sunday at midnight UTC
+  workflow_dispatch: # Allows manual trigger
 
 jobs:
   build-and-push:

.github/workflows/update-base-images.yml

@@ -0,0 +1,29 @@
+name: Update base image versions
+
+on:
+  schedule:
+    - cron: "0 0 * * 1" # Every Monday at midnight UTC
+  workflow_dispatch: # Allows manual trigger
+
+jobs:
+  update:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+
+      - name: Update platforms.json
+        run: ./build-in-container.py --update
+
+      - name: Create pull request
+        uses: peter-evans/create-pull-request@v8
+        with:
+          commit-message: "Updated base image versions in platforms.json"
+          branch: update-base-images
+          title: "Updated base image versions"
+          body: |
+            Automated update of `image_version` in `platforms.json` to the
+            latest tags from ghcr.io.

build-in-container.md

@@ -38,19 +38,22 @@ specified, defaults will:
 | `--role`       | `agent` or `hub` (not required for `--push-image`)      |
 | `--build-type` | `DEBUG` or `RELEASE` (not required for `--push-image`)  |
 
+None of the above arguments are required for `--update`.
+
 ### Optional arguments
 
-| Option             | Default                          | Description                                                 |
-| ------------------ | -------------------------------- | ----------------------------------------------------------- |
-| `--output-dir`     | `./output`                       | Where to write output packages                              |
-| `--cache-dir`      | `~/.cache/cfengine/buildscripts` | Dependency cache directory                                  |
-| `--build-number`   | `1`                              | Build number for package versioning                         |
-| `--version`        | auto                             | Override version string                                     |
-| `--rebuild-image`  |                                  | Force rebuild of Docker image (bypasses Docker layer cache) |
-| `--push-image`     |                                  | Build image and push to registry, then exit                 |
-| `--shell`          |                                  | Drop into a bash shell inside the container for debugging   |
-| `--list-platforms` |                                  | List available platforms and exit                           |
-| `--source-dir`     | parent of `buildscripts/`        | Root directory containing repos                             |
+| Option             | Default                          | Description                                                         |
+| ------------------ | -------------------------------- | ------------------------------------------------------------------- |
+| `--output-dir`     | `./output`                       | Where to write output packages                                      |
+| `--cache-dir`      | `~/.cache/cfengine/buildscripts` | Dependency cache directory                                          |
+| `--build-number`   | `1`                              | Build number for package versioning                                 |
+| `--version`        | auto                             | Override version string                                             |
+| `--rebuild-image`  |                                  | Force rebuild of Docker image (bypasses Docker layer cache)         |
+| `--push-image`     |                                  | Build image and push to registry, then exit                         |
+| `--update`         |                                  | Fetch latest image versions from registry and update platforms.json |
+| `--shell`          |                                  | Drop into a bash shell inside the container for debugging           |
+| `--list-platforms` |                                  | List available platforms and exit                                   |
+| `--source-dir`     | parent of `buildscripts/`        | Root directory containing repos                                     |
 
 ## Supported platforms
 
@@ -62,8 +65,8 @@ specified, defaults will:
 | `debian-11` | `debian:11`    |
 | `debian-12` | `debian:12`    |
 
-Adding a new Debian/Ubuntu platform requires only a new entry in the `PLATFORMS`
-dict in `build-in-container.py`. Adding a non-debian based platform (e.g.,
+Adding a new Debian/Ubuntu platform requires only a new entry in `platforms.json`.
+Adding a non-debian based platform (e.g.,
 RHEL/CentOS) requires a new `container/Dockerfile.rhel` plus platform entries.
 
 ## How it works
@@ -112,8 +115,8 @@ hash and skips rebuilding when nothing has changed.
 
 ### Container registry
 
-Images are hosted at `ghcr.io/cfengine` and versioned via `IMAGE_VERSION` in
-`build-in-container.py`. To push a new image:
+Images are hosted at `ghcr.io/cfengine` and versioned per-platform via
+`image_version` in `platforms.json`. To push a new image:
 
 ```bash
 # Build and push a single platform
@@ -129,7 +132,24 @@ which handles authentication automatically.
 #### GitHub Actions workflow
 
 The `build-base-images.yml` workflow builds and pushes images for every
-supported platform. It is triggered manually via `workflow_dispatch`.
+supported platform. It runs weekly (Sunday at midnight UTC) and can also be
+triggered manually via `workflow_dispatch`.
+
+After the workflow pushes new images, update `platforms.json` to use them:
+
+```bash
+# Update all platforms to the latest registry version
+./build-in-container.py --update
+
+# Update a single platform
+./build-in-container.py --update --platform ubuntu-22
+```
+
+The `update-base-images.yml` workflow automates this step. It runs weekly
+(Monday at midnight UTC) and can also be triggered manually. It calls
+`./build-in-container.py --update` and opens a pull request with any
+`platforms.json` changes. This workflow requires `contents: write` and
+`pull-requests: write` permissions.
 
 The workflow authenticates to `ghcr.io` using the automatic `GITHUB_TOKEN`
 provided by GitHub Actions. For this to work:
@@ -140,16 +160,16 @@ provided by GitHub Actions. For this to work:
 - After the first push, each package defaults to private. To allow anonymous
   pulls, go to the package on GitHub (**your org → Packages**), open **Package
   settings**, and change the visibility to **Public**. This is a one-time step
-  per package — new tags (e.g. from bumping `IMAGE_VERSION`) inherit the
+  per package — new tags (e.g. from bumping `image_version`) inherit the
   existing visibility.
 
 ### Updating the toolchain
 
 1. Edit `container/Dockerfile.debian` as needed
 2. Test locally with `--rebuild-image`
-3. Bump `IMAGE_VERSION` in `build-in-container.py`
-4. Commit the Dockerfile change + version bump
-5. Push new images by triggering the GitHub Actions workflow
+3. Commit and merge the Dockerfile change
+4. Push new images by triggering the `build-base-images.yml` workflow
+5. Trigger the `update-base-images.yml` workflow to open a PR updating `platforms.json`
 
 ## Debugging
 

build-in-container.py

@@ -6,49 +6,26 @@
 """
 
 import argparse
+import datetime
+import functools
 import hashlib
+import json
 import logging
 import subprocess
 import sys
+import urllib.request
 from pathlib import Path
 
 log = logging.getLogger("build-in-container")
 
 IMAGE_REGISTRY = "ghcr.io/cfengine"
-IMAGE_VERSION = "1"
-
-PLATFORMS = {
-    "ubuntu-20": {
-        "image_tag": f"cfengine-builder-ubuntu-20:{IMAGE_VERSION}",
-        "base_image": "ubuntu:20.04",
-        "dockerfile": "Dockerfile.debian",
-        "extra_build_args": {"NCURSES_PKGS": "libncurses5 libncurses5-dev"},
-    },
-    "ubuntu-22": {
-        "image_tag": f"cfengine-builder-ubuntu-22:{IMAGE_VERSION}",
-        "base_image": "ubuntu:22.04",
-        "dockerfile": "Dockerfile.debian",
-        "extra_build_args": {},
-    },
-    "ubuntu-24": {
-        "image_tag": f"cfengine-builder-ubuntu-24:{IMAGE_VERSION}",
-        "base_image": "ubuntu:24.04",
-        "dockerfile": "Dockerfile.debian",
-        "extra_build_args": {},
-    },
-    "debian-11": {
-        "image_tag": f"cfengine-builder-debian-11:{IMAGE_VERSION}",
-        "base_image": "debian:11",
-        "dockerfile": "Dockerfile.debian",
-        "extra_build_args": {},
-    },
-    "debian-12": {
-        "image_tag": f"cfengine-builder-debian-12:{IMAGE_VERSION}",
-        "base_image": "debian:12",
-        "dockerfile": "Dockerfile.debian",
-        "extra_build_args": {},
-    },
-}
+
+
+@functools.cache
+def get_config():
+    """Load and cache platform configuration from platforms.json."""
+    config_path = Path(__file__).resolve().parent / "platforms.json"
+    return json.loads(config_path.read_text())
 
 
 def detect_source_dir():
@@ -88,7 +65,7 @@ def image_needs_rebuild(image_tag, current_hash):
 
 def build_image(platform_name, platform_config, script_dir, rebuild=False):
     """Build the Docker image for the given platform."""
-    image_tag = platform_config["image_tag"]
+    image_tag = f"{platform_config['image_name']}:{platform_config['image_version']}"
     dockerfile_name = platform_config["dockerfile"]
     dockerfile_path = script_dir / "container" / dockerfile_name
     current_hash = dockerfile_hash(dockerfile_path)
@@ -104,7 +81,7 @@ def build_image(platform_name, platform_config, script_dir, rebuild=False):
         "-f",
         str(dockerfile_path),
         "--build-arg",
-        f"BASE_IMAGE={platform_config['base_image']}",
+        f"BASE_IMAGE={platform_config['base_image']}@{platform_config['base_image_sha']}",
         "--label",
         f"dockerfile-hash={current_hash}",
         "-t",
@@ -132,7 +109,8 @@ def build_image(platform_name, platform_config, script_dir, rebuild=False):
 
 def registry_image_ref(platform_name):
     """Return the fully-qualified registry image reference for a platform."""
-    return f"{IMAGE_REGISTRY}/{PLATFORMS[platform_name]['image_tag']}"
+    platform = get_config()[platform_name]
+    return f"{IMAGE_REGISTRY}/{platform['image_name']}:{platform['image_version']}"
 
 
 def pull_image(platform_name):
@@ -152,24 +130,11 @@ def pull_image(platform_name):
     return ref
 
 
-def image_exists_in_registry(platform_name):
-    """Check if an image tag already exists in the registry."""
-    ref = registry_image_ref(platform_name)
-    result = subprocess.run(
-        ["docker", "manifest", "inspect", ref],
-        capture_output=True,
-        text=True,
-    )
-    return result.returncode == 0
-
-
 def push_image(platform_name, local_tag):
-    """Tag a local image with the registry reference and push it."""
-    ref = registry_image_ref(platform_name)
-
-    if image_exists_in_registry(platform_name):
-        log.error(f"Image {ref} already exists. Bump IMAGE_VERSION.")
-        sys.exit(1)
+    """Tag a local image with a timestamped version and push it."""
+    image_name = get_config()[platform_name]["image_name"]
+    version = datetime.datetime.now(datetime.timezone.utc).strftime("%Y%m%dT%H%M%SZ")
+    ref = f"{IMAGE_REGISTRY}/{image_name}:{version}"
 
     log.info(f"Tagging {local_tag} as {ref}...")
     result = subprocess.run(["docker", "tag", local_tag, ref])
@@ -183,6 +148,46 @@ def push_image(platform_name, local_tag):
         log.error("Docker push failed.")
         sys.exit(1)
 
+    log.info(f"Update image_version to \"{version}\" in platforms.json.")
+
+
+def latest_registry_version(image_name):
+    """Query ghcr.io for the latest tag of an image."""
+    # Anonymous token — no credentials needed for public images
+    token_url = f"https://ghcr.io/token?scope=repository:cfengine/{image_name}:pull"
+    token = json.loads(urllib.request.urlopen(token_url).read())["token"]
+
+    tags_url = f"https://ghcr.io/v2/cfengine/{image_name}/tags/list"
+    req = urllib.request.Request(
+        tags_url, headers={"Authorization": f"Bearer {token}"}
+    )
+    tags = json.loads(urllib.request.urlopen(req).read()).get("tags", [])
+    if not tags:
+        return None
+    return sorted(tags)[-1]
+
+
+def update_platform_versions(platform_name=None):
+    """Fetch latest image versions from the registry and update platforms.json."""
+    config = get_config()
+
+    platforms = [platform_name] if platform_name else list(config.keys())
+    for name in platforms:
+        image_name = config[name]["image_name"]
+        latest = latest_registry_version(image_name)
+        if latest is None:
+            log.warning(f"No tags found for {image_name}, skipping.")
+            continue
+        old = config[name]["image_version"]
+        if old == latest:
+            log.info(f"{name}: already at {latest}")
+        else:
+            config[name]["image_version"] = latest
+            log.info(f"{name}: {old} -> {latest}")
+
+    config_path = Path(__file__).resolve().parent / "platforms.json"
+    config_path.write_text(json.dumps(config, indent=2) + "\n")
+
 
 def run_container(args, image_tag, source_dir, script_dir):
     """Run the build inside a Docker container."""
@@ -252,7 +257,7 @@ def parse_args():
     )
     parser.add_argument(
         "--platform",
-        choices=list(PLATFORMS.keys()),
+        choices=list(get_config().keys()),
         help="Target platform",
     )
     parser.add_argument(
@@ -300,6 +305,11 @@ def parse_args():
         action="store_true",
         help="Build image and push to registry, then exit",
     )
+    parser.add_argument(
+        "--update",
+        action="store_true",
+        help="Fetch latest image version from registry and update platforms.json",
+    )
     parser.add_argument(
         "--shell",
         action="store_true",
@@ -318,11 +328,15 @@ def parse_args():
 
     if args.list_platforms:
         print("Available platforms:")
-        for name, config in PLATFORMS.items():
+        for name, config in get_config().items():
             print(f"  {name:15s}  ({config['base_image']})")
         sys.exit(0)
 
-    # --platform is always required (except --list-platforms handled above)
+    if args.update:
+        # --platform is optional for --update; updates all if omitted
+        return args
+
+    # --platform is always required (except --list-platforms/--update handled above)
     if not args.platform:
         parser.error("missing required argument --platform")
 
@@ -349,6 +363,10 @@ def main():
         format="%(message)s",
     )
 
+    if args.update:
+        update_platform_versions(args.platform)
+        return
+
     # Detect source directory
     if args.source_dir:
         source_dir = Path(args.source_dir).resolve()
@@ -357,7 +375,7 @@ def main():
 
     script_dir = source_dir / "buildscripts"
 
-    platform_config = PLATFORMS[args.platform]
+    platform_config = get_config()[args.platform]
 
     if args.push_image:
         image_tag = build_image(