Add the Alertmanager ROCK to OCI Factory (#12)

* prepare repo for oci-factory

* add workflow to open PRs to oci-factory as a test

* build rock 0.24 to trigger new CI on 0.25

* enable manual action for release to oci-factory as a test

* return to build 0.25

* add badge for future oci-releases

* use workflow from main

* fix alertmanager link in README

.github/workflows/pull-request.yaml

@@ -0,0 +1,16 @@
+name: Pull Requests
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+on:
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  pull-request:
+    name: PR
+    uses: canonical/observability/.github/workflows/rock-pull-request.yaml@main
+    secrets: inherit

.github/workflows/rock-release-dev.yaml

@@ -0,0 +1,18 @@
+name: "Publish ROCK to GHCR:dev"
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+on:
+  workflow_dispatch: {}
+  push:
+    branches:
+      - main
+
+jobs:
+  build:
+    uses: canonical/observability/.github/workflows/rock-release-dev.yaml@main
+    secrets: inherit
+    with:
+      rock-name: alertmanager

.github/workflows/rock-release-oci-factory.yaml

@@ -0,0 +1,13 @@
+name: Open a PR to OCI Factory
+
+on:
+  workflow_dispatch: {} # TODO: Test to see if this works
+  push:
+    branches:
+      - main
+
+jobs:
+  build:
+    uses: canonical/observability/.github/workflows/rock-release-oci-factory.yaml@main
+    with:
+      rock-name: alertmanager

.github/workflows/update-rock.yaml → .github/workflows/rock-update.yaml

@@ -7,7 +7,7 @@ on:
 
 jobs:
   build:
-    uses: canonical/observability/.github/workflows/update-rock.yaml@main
+    uses: canonical/observability/.github/workflows/rock-update.yaml@main
     with:
       rock-name: alertmanager
       source-repo: prometheus/alertmanager

README.md

@@ -1,31 +1,16 @@
 # alertmanager-rock
 
-[![Build ROCK](https://github.com/canonical/alertmanager-rock/actions/workflows/build-rock.yaml/badge.svg)](https://github.com/canonical/alertmanager-rock/actions/workflows/build-rock.yaml)
+[![Open a PR to OCI Factory](https://github.com/canonical/alertmanager-rock/actions/workflows/rock-release-oci-factory.yaml/badge.svg)](https://github.com/canonical/alertmanager-rock/actions/workflows/rock-release-oci-factory.yaml)
+[![Publish to GHCR:dev](https://github.com/canonical/alertmanager-rock/actions/workflows/rock-release-dev.yaml/badge.svg)](https://github.com/canonical/alertmanager-rock/actions/workflows/rock-release-dev.yaml)
+[![Update ROCK](https://github.com/canonical/alertmanager-rock/actions/workflows/rock-update.yaml/badge.svg)](https://github.com/canonical/alertmanager-rock/actions/workflows/rock-update.yaml)
 
-Build an alertmanager image using
-[rockcraft](https://github.com/canonical/rockcraft), maintaining the same file
-hierarchy as the
-[`prometheus/alertmanager`](https://github.com/prometheus/alertmanager/blob/main/Dockerfile)
-image.
+[ROCKs](https://canonical-rockcraft.readthedocs-hosted.com/en/latest/) for [Alertmanager](https://prometheus.io/docs/alerting/latest/alertmanager/).  
+This repository holds all the necessary files to build ROCKs for the upstream versions we support. The Alertmanager ROCK is used by the [alertmanager-k8s-operator](https://github.com/canonical/alertmanager-k8s-operator) charm.
 
-## Usage
-```shell
-rockcraft pack -v
-```
+The ROCKs on this repository are built with [OCI Factory](https://github.com/canonical/oci-factory/), which also takes care of periodically rebuilding the images.
 
-## Manual verification
-```shell
-tar tf alertmanager_0.24.0_amd64.rock
-tar -O -xf alertmanager_0.24.0_amd64.rock oci-layout
+Automation takes care of:
+* validating PRs, by simply trying to build the ROCK;
+* pulling upstream releases, creating a PR with the necessary files to be manually reviewed;
+* releasing to GHCR at [ghcr.io/canonical/alertmanager:dev](https://ghcr.io/canonical/alertmanager:dev), when merging to main, for development purposes.
 
-skopeo --insecure-policy copy oci-archive:alertmanager_0.24.0_amd64.rock docker-daemon:alertmanager:0.24.0
-dive alertmanager:0.24.0
-
-docker run --rm -d -p 9093:9093 alertmanager:0.24.0
-curl localhost:9093/api/v1/alerts
-```
-
-## Build automation
-This repo has workflows in place to:
-- update `rockcraft.yaml` when new versions of alertmanager are published;
-- publish a new rock on every merge.