ci: build head docker images on changes in main

Enables a docker build step on every commit to the main branch.
Each docker image will have a tag `head-<architecture>`. E.g.: vcluster-oss:head-arm64v8 or vcluster-oss:head-amd64

Author: sydorovdmytro

.github/workflows/update-cache.yaml

@@ -23,6 +23,9 @@ jobs:
 
       - run: git fetch --force --tags
 
+      - name: Set branch name
+        run: echo "CI_BRANCH=${GITHUB_REF#refs/heads/}" >> $GITHUB_ENV
+
       - name: Set up Go
         uses: actions/setup-go@v5
         id: cache
@@ -40,8 +43,8 @@ jobs:
         run: |
           set -x
           # Build syncer
-          TELEMETRY_PRIVATE_KEY="" goreleaser build --single-target --snapshot --id vcluster --clean --output ./vcluster
+          CI_BRANCH="${CI_BRANCH}" TELEMETRY_PRIVATE_KEY="" goreleaser build --single-target --snapshot --id vcluster --clean --output ./vcluster
           # Build cli
-          TELEMETRY_PRIVATE_KEY="" goreleaser build --single-target --snapshot --id vcluster-cli --clean --output ./vcluster
+          CI_BRANCH="${CI_BRANCH}" TELEMETRY_PRIVATE_KEY="" goreleaser build --single-target --snapshot --id vcluster-cli --clean --output ./vcluster
           # Build tests for cache
           go test -mod=vendor -test.v -c ./test/e2e

.goreleaser.yaml

@@ -10,6 +10,7 @@ before:
     - '{{ if not .IsSnapshot }}just generate-vcluster-latest-images {{ .Version }}{{ else }}echo "Skipping generate-vcluster-latest-images"{{ end }}'
     - '{{ if not .IsSnapshot }}just generate-vcluster-optional-images{{ else }}echo "Skipping generate-vcluster-optional-images"{{ end }}'
     - '{{ if not .IsSnapshot }}just generate-matrix-specific-images {{ .Version }}{{ else }}echo "Skipping generate-matrix-specific-images"{{ end }}'
+    - '{{ if or .IsSnapshot (eq .Env.CI_BRANCH "main") }}echo "Building head images for main branch commit $(git rev-parse --short HEAD)"{{ end }}'
 
 source:
   format: tar.gz
@@ -182,6 +183,8 @@ dockers:
       - '{{ if eq .Prerelease "" }}ghcr.io/loft-sh/vcluster-oss:latest-amd64{{ end }}'
       - '{{ if eq .Prerelease "" }}ghcr.io/loft-sh/vcluster-oss:{{ .Major }}-amd64{{ end }}'
       - '{{ if eq .Prerelease "" }}ghcr.io/loft-sh/vcluster-oss:{{ .Major }}.{{ .Minor }}-amd64{{ end }}'
+      # Add head tag for main branch
+      - '{{ if or .IsSnapshot (eq .Env.CI_BRANCH "main") }}ghcr.io/loft-sh/vcluster-oss:head-amd64{{ end }}'
     use: buildx
     dockerfile: Dockerfile.release
     ids:
@@ -199,6 +202,8 @@ dockers:
       - '{{ if eq .Prerelease "" }}ghcr.io/loft-sh/vcluster-oss:latest-arm64v8{{ end }}'
       - '{{ if eq .Prerelease "" }}ghcr.io/loft-sh/vcluster-oss:{{ .Major }}-arm64v8{{ end }}'
       - '{{ if eq .Prerelease "" }}ghcr.io/loft-sh/vcluster-oss:{{ .Major }}.{{ .Minor }}-arm64v8{{ end }}'
+      # Add head tag for main branch
+      - '{{ if or .IsSnapshot (eq .Env.CI_BRANCH "main") }}ghcr.io/loft-sh/vcluster-oss:head-arm64v8{{ end }}'
     use: buildx
     goarch: arm64
     dockerfile: Dockerfile.release
@@ -303,6 +308,21 @@ docker_manifests:
       - loftsh/vcluster-cli:{{ .Major }}-arm64v8
     skip_push: auto
 
+  # --- Head multi arch manifest ---
+  - name_template: ghcr.io/loft-sh/vcluster-oss:head
+    image_templates:
+      - ghcr.io/loft-sh/vcluster-oss:head-amd64
+      - ghcr.io/loft-sh/vcluster-oss:head-arm64v8
+    # Only push on main branch
+    skip_push: '{{ and (ne .Env.CI_BRANCH "main") (not .IsSnapshot) }}'
+
+  # --- Head multi arch manifest for vcluster-cli ---
+  - name_template: ghcr.io/loft-sh/vcluster-cli:head
+    image_templates:
+      - ghcr.io/loft-sh/vcluster-cli:head-amd64
+      - ghcr.io/loft-sh/vcluster-cli:head-arm64v8
+    # Only push on main branch
+    skip_push: '{{ and (ne .Env.CI_BRANCH "main") (not .IsSnapshot) }}'
 docker_signs:
   - cmd: cosign
     env: