Add CI workflow

.github/workflows/controller-sharding.yaml

@@ -0,0 +1,79 @@
+name: controller-sharding
+
+on:
+  release:
+    types:
+    - published
+  push:
+    branches:
+    - '*'
+    tags:
+    - v*
+    paths-ignore:
+    - "webhosting-operator/**"
+    - "**.md"
+  pull_request:
+    paths-ignore:
+    - "webhosting-operator/**"
+    - "**.md"
+
+jobs:
+  verify:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+    - uses: actions/setup-go@v4
+      with:
+        go-version-file: go.mod
+    - name: Verify
+      run: make verify
+
+  images:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - uses: actions/setup-go@v4
+      with:
+        go-version-file: go.mod
+    - uses: ko-build/setup-ko@v0.6
+      with:
+        version: v0.15.0
+    - name: Prepare image metadata
+      id: meta
+      # generate comma-separated tags and labels for image build (similar to docker/metadata-action)
+      run: |
+        short_ref=${{ github.ref_name }}
+        if ${{ github.event_name == 'pull_request' }} ; then
+          # for PR events, ref_name is '<pr-number>/merge' but tags may not contain /
+          short_ref=pr-${{ github.event.pull_request.number }}
+        fi
+
+        tags=(
+          $short_ref
+          sha-$( echo ${{ github.sha }} | head -c7 )
+        )
+
+        if ${{ github.ref_name == 'master' }} ; then
+          tags+=( latest )
+        fi
+
+        echo "tags=$(IFS=, ; echo "${tags[*]}")" >> $GITHUB_OUTPUT
+
+        labels=(
+          org.opencontainers.image.created=$( date -u +%Y-%m-%dT%H:%M:%SZ )
+          org.opencontainers.image.licenses=Apache-2.0
+          org.opencontainers.image.revision=${{ github.sha }}
+          org.opencontainers.image.source=https://github.com/${{ github.repository }}
+          org.opencontainers.image.url=https://github.com/${{ github.repository }}
+          org.opencontainers.image.version=$short_ref
+        )
+
+        echo "labels=$(IFS=, ; echo "${labels[*]}")" >> $GITHUB_OUTPUT
+    - name: ko build
+      run: |
+        set -ex
+
+        ko build --push=${{ github.event_name != 'pull_request' }} --sbom none --base-import-paths --platform linux/amd64,linux/arm64 \
+          --tags "${{ steps.meta.outputs.tags }}" --image-label "${{ steps.meta.outputs.labels }}" \
+          ./cmd/sharder