dexop: add github container builds workflow

Author: skrobul

.github/workflows/build-dexop.yaml

@@ -0,0 +1,48 @@
+---
+name: build-container-images
+
+on:
+  workflow_dispatch:
+  pull_request:
+    paths:
+      - "go/dexop/**"
+  push:
+    tags:
+      - dexop-*
+    paths:
+      - "go/dexop/**"
+  merge_group:
+    types: [checks_requested]
+
+jobs:
+  build-ghcr-registry:
+    runs-on: ubuntu-latest
+    permissions:
+      packages: write
+      contents: read
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@b5ca514318bd6ebac0fb2aedd5d36ec1b5c232a2 # v3
+
+      - name: Login to ghcr.io
+        uses: docker/login-action@74a5d142397b4f367a81961eba4e8cd7edddf772 # v3
+        with:
+          registry: "ghcr.io"
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract tag name
+        id: extract_tag
+        run: echo "DEXOP_VERSION=${GITHUB_REF#refs/tags/}" >> $GITHUB_OUTPUT
+
+      - name: Build and deploy Dexop image
+        uses: docker/build-push-action@471d1dc4e07e5cdedd4c2171150001c434f0b7a4 # v6
+        with:
+          context: go/dexop/
+          file: go/dexop/Dockerfile
+          # push for all main branch commits
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ghcr.io/${{ github.repository }}/dexop:latest,ghcr.io/${{ github.repository }}/dexop:${{ env.DEXOP_VERSION }}
+          labels: |
+            org.opencontainers.image.version=${{ env.DEXOP_VERSION }}