build: Build the docker image as a part of CI.

Rather than relying on a different build workflow to have run on master,
build the image(s) we need for testing within this workflow.  To reduce
test time, use the github actions cache to cache intermediate layers.

See https://docs.docker.com/build/cache/backends/gha/ for mre details.

Author: feanil

.github/workflows/ci.yml

@@ -17,33 +17,20 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
-      - name: Configure AWS credentials
-        uses: aws-actions/configure-aws-credentials@v4
-        with:
-          aws-access-key-id: ${{ secrets.TOOLS_EDX_ECR_USER_AWS_ACCESS_KEY_ID }}
-          aws-secret-access-key: ${{ secrets.TOOLS_EDX_ECR_USER_AWS_SECRET_ACCESS_KEY }}
-          aws-region: us-east-1
-
-      - name: Login to Amazon ECR
-        id: login-ecr
-        uses: aws-actions/amazon-ecr-login@v2
-
       - name: Parse custom apparmor profile
         run: sudo apparmor_parser -r -W apparmor-profiles/home.sandbox.codejail_sandbox-python3.bin.python
 
-      - name: Pull codejail CI image
-        run: docker pull 257477529851.dkr.ecr.us-east-1.amazonaws.com/openedx-codejail:latest
-
       - name: Build latest code changes into CI image
         run: |
-          docker build --cache-from 257477529851.dkr.ecr.us-east-1.amazonaws.com/openedx-codejail \
-            -t 257477529851.dkr.ecr.us-east-1.amazonaws.com/openedx-codejail \
+          docker build -t openedx-codejail \
+            --cache-to type=gha \
+            --cache-from type=gha \
             --build-arg python_version=${{ matrix.python_version }} .
 
       - name: Run container with custom apparmor profile and codejail CI image
         run: |
           docker run --name=codejail --privileged -d --security-opt apparmor=apparmor_profile \
-            257477529851.dkr.ecr.us-east-1.amazonaws.com/openedx-codejail tail -f /dev/null
+            openedx-codejail tail -f /dev/null
 
       - name: Run Non Proxy Tests
         run: docker exec -t codejail bash -c 'make clean && make test_no_proxy'