Make docker build action more consistent. (#4)

Author: Gerrit91

.github/workflows/main.yml

@@ -1,10 +1,16 @@
-name: build
+---
+name: Docker Build Action
 on:
+  pull_request:
+    branches:
+      - main
+  release:
+    types:
+      - published
   push:
     branches:
-      - "main"
-    tags:
-      - 'v*'
+      - main
+
 env:
   REGISTRY: ghcr.io
   IMAGE_NAME: ${{ github.repository }}
@@ -14,7 +20,6 @@ jobs:
     name: Build
     runs-on: ubuntu-latest
     steps:
-
     - name: Set up Go 1.18
       uses: actions/setup-go@v2
       with:
@@ -36,21 +41,15 @@ jobs:
         username: ${{ github.actor }}
         password: ${{ secrets.GITHUB_TOKEN }}
 
-    - name: Extract metadata (tags, labels) for Docker
-      id: meta
-      uses: docker/metadata-action@v3
-      with:
-        images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
-        tags: |
-          type=ref,event=branch
-          type=ref,event=pr
-          type=semver,pattern={{version}}
-          type=semver,pattern={{major}}.{{minor}}
+    - name: Make tag
+      run: |
+        [ "${GITHUB_EVENT_NAME}" == 'pull_request' ] && echo "tag=${GITHUB_HEAD_REF##*/}" >> $GITHUB_ENV || true
+        [ "${GITHUB_EVENT_NAME}" == 'release' ] && echo "tag=${GITHUB_REF##*/}" >> $GITHUB_ENV || true
+        [ "${GITHUB_EVENT_NAME}" == 'push' ] && echo "tag=latest" >> $GITHUB_ENV || true
 
-    - name: Build and push Docker image
+    - name: Build and push image
       uses: docker/build-push-action@v2
       with:
         context: .
         push: true
-        tags: ${{ steps.meta.outputs.tags }}
-        labels: ${{ steps.meta.outputs.labels }}
+        tags: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ env.tag }}