streamline multi-arch build, part of #81

.github/workflows/ci.yaml

@@ -36,14 +36,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
-    - name: Create a new container builder
-      run: docker buildx create --name builder && docker buildx use builder
-    - name: Build the container image
-      run: docker buildx build --platform linux/amd64 --tag $IMAGE_NAME .
     - name: Log into GitHub Container Registry
       run: echo "${{ secrets.REGISTRY_ACCESS_TOKEN }}" | docker login https://ghcr.io -u ${{ github.actor }} --password-stdin
-    - name: Push image to GitHub Container Registry
+    - name: Build the container image
       run: |
         LATEST_TAG=ghcr.io/meeb/$IMAGE_NAME:latest
-        docker tag $IMAGE_NAME $LATEST_TAG
-        docker push $LATEST_TAG
+        docker buildx create --name builder
+        docker buildx use builder
+        docker buildx build --platform linux/amd64 --tag $IMAGE_NAME --push .