ci: improve environment handling

.github/workflows/build-and-publish.yml

@@ -12,14 +12,16 @@ jobs:
   # define job to build and publish docker image
 
   build-docker-image:
-    name: Build Docker image and push to repositories
+    name: "Build docker image"
     # run only when code is compiling and tests are passing
     runs-on: ubuntu-latest
 
     # steps to perform in job
     steps:
       - name: Set current date as env variable
-        run: echo "BUILD_VERSION=v$(date +'%Y%m%d_%H%M')" >> $GITHUB_ENV
+        run: |
+          export BUILD_VERSION=v$(date +'%Y%m%d_%H%M')
+          echo "BUILD_VERSION=$BUILD_VERSION" >> $GITHUB_ENV
 
       - name: Checkout code
         uses: actions/checkout@v2
@@ -28,10 +30,7 @@ jobs:
         id: buildx
         uses: docker/setup-buildx-action@v1
 
-      - name: Image digest
-        run: echo ${{ steps.docker_build.outputs.digest }}
-
-      - name: Build image and push to Docker Hub and GitHub Container Registry
+      - name: Build image and save as file
         uses: docker/build-push-action@v2
         with:
           # relative path to the place where source code with Dockerfile
@@ -43,17 +42,22 @@ jobs:
             glenux/teaching-boilerplate:latest
           outputs: type=docker,dest=/tmp/teaching-boilerplate.image.tar
 
-      - name: Set current date as env variable
-        run: echo "BUILD_VERSION=v$(date +'%Y%m%d_%H%M')" >> /tmp/env
+      - name: Image digest
+        run: echo ${{ steps.docker_build.outputs.digest }}
+
+      - name: Save important variables as extra.env
+        run: |
+          echo "BUILD_VERSION=$BUILD_VERSION" >> /tmp/extra.env
+          cat /tmp/extra.env
 
       - name: Upload artifact
         uses: actions/upload-artifact@v2
         with:
-          name: myimage
-          path: /tmp/teaching-boilerplate.image.tar
+          name: teaching-boilerplate-image
+          path: /tmp/
 
   test-docker-image:
-    name: Build Docker image and push to repositories
+    name: "Test docker image (build PDF and HTML)"
     needs: build-docker-image
     runs-on: ubuntu-latest
 
@@ -61,6 +65,21 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v2
 
+      - name: Download artifact
+        uses: actions/download-artifact@v2
+        with:
+          name: teaching-boilerplate-image
+          path: /tmp
+
+      - name: Load environment
+        run: |
+          cat /tmp/extra.env >> $GITHUB_ENV
+
+      - name: Load image
+        run: |
+          docker load --input /tmp/myimage.tar
+          docker image ls -a
+
       - name: Build HTML for docs
         run: ./scripts/gx-teaching . build-docs-html
 
@@ -75,14 +94,28 @@ jobs:
 
   push-docker-image:
     needs: test-docker-image
-    name: Build Docker image and push to repositories
+    name: "Push docker image to registry"
     runs-on: ubuntu-latest
     steps:
-      # setup Docker buld action
+      - name: Download artifact
+        uses: actions/download-artifact@v2
+        with:
+          name: teaching-boilerplate-image
+          path: /tmp
+
+      - name: Load environment
+        run: |
+          cat /tmp/extra.env >> $GITHUB_ENV
+
       - name: Set up Docker Buildx
         id: buildx
         uses: docker/setup-buildx-action@v1
 
+      - name: Load image
+        run: |
+          docker load --input /tmp/myimage.tar
+          docker image ls -a
+
       - name: Login to DockerHub
         uses: docker/login-action@v1
         with: