update go-version to 1.21, add build & push docker workflow

.github/workflows/build-push-staging.yml

@@ -0,0 +1,58 @@
+name: 'build & push docker staging'
+
+on:
+  pull_request_target:
+    branches: [main]
+    types:
+      - closed
+
+jobs:
+  if_merged:
+    if: github.event.pull_request.merged == true
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Setup golang environment
+        uses: actions/setup-go@v4
+        with:
+          go-version: '1.21'
+
+      - name: Install dependencies
+        run: go mod tidy
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ secrets.DOCKER_ENDPOINT }}
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+
+      - name: set build env variables
+        shell: bash
+        run: |
+          REPO_VERSION=$(git rev-parse --git-dir > /dev/null 2>&1 && git fetch -q origin --tags && git describe --always --dirty --tags)
+          REPO_REV=$(git rev-parse --git-dir > /dev/null 2>&1 && git rev-parse HEAD 2>/dev/null)
+          BUILD_DATE=$(date -u +%FT%T)
+          echo "REPO_VERSION=$REPO_VERSION" >> $GITHUB_ENV
+          echo "REPO_REV=$REPO_REV" >> $GITHUB_ENV
+          echo "BUILD_DATE=$BUILD_DATE" >> $GITHUB_ENV
+
+      - name: Build and push
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          build-args: |
+            VERSION=${{ env.REPO_VERSION }}
+            REPO_REV=${{ env.REPO_REV }}
+            DATE=${{ env.BUILD_DATE }}
+          tags: ${{ secrets.DOCKER_ENDPOINT }}${{ secrets.DOCKER_REPO }}/fishymetrics:${{ env.REPO_VERSION }}

.github/workflows/pr-prechecks.yml

@@ -10,12 +10,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup golang environment
         uses: actions/setup-go@v4
         with:
-          go-version: '1.19'
+          go-version: '1.21'
 
       - name: Install dependencies
         run: go mod tidy
@@ -36,12 +36,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup golang environment
         uses: actions/setup-go@v4
         with:
-          go-version: '1.19'
+          go-version: '1.21'
 
       - name: Install dependencies
         run: go mod tidy