Squash image layers to save disk space (#366)

Related: containers/podman#5806

Author: ssbarnea

.github/actions/build-test/action.yml

@@ -46,7 +46,7 @@ runs:
         ansible-builder create -f ${{ github.workspace }}/execution-environment.yml --output-filename Containerfile -v3
 
     - name: Build base image for ${{ matrix.platform }}
-      uses: docker/build-push-action@v5
+      uses: docker/build-push-action@v6
       id: build-base
       with:
         context: context
@@ -66,7 +66,7 @@ runs:
 
     - name: Build final image for ${{ matrix.platform }}
       id: build-final
-      uses: docker/build-push-action@v5
+      uses: docker/build-push-action@v6
       with:
         context: ${{ github.workspace }}/final
         provenance: false
@@ -80,6 +80,12 @@ runs:
         cache-from: type=gha,scope=build-${{ env.PLATFORM_PAIR }}
         cache-to: type=gha,scope=build-${{ env.PLATFORM_PAIR }}
 
+    - name: Squash image layers to save disk space
+      shell: bash
+      run: |
+        python3 -m pip install --upgrade docker-squash
+        docker-squash ${{ inputs.namespace }}/${{ inputs.final_image }}:test
+
     - name: Run tests against the container
       shell: bash
       run: |
@@ -90,7 +96,7 @@ runs:
     - name: Push the built image to ${{ inputs.registry }} by digest for ${{ matrix.platform }}
       id: push-final
       if: inputs.push == 'true'
-      uses: docker/build-push-action@v5
+      uses: docker/build-push-action@v6
       with:
         context: ${{ github.workspace }}/final
         provenance: false

.gitignore

@@ -176,3 +176,4 @@ _readthedocs
 
 # ansible-builder
 context
+collections

tox.ini

@@ -122,8 +122,8 @@ commands_pre =
 commands =
     python -m build --outdir {toxinidir}/final/dist/ --wheel {toxinidir}
     ansible-builder create -f execution-environment.yml --output-filename Containerfile -v3
-    podman build context/ --tag community-ansible-dev-tools-base:latest
-    podman build final/ --tag community-ansible-dev-tools:test
+    podman build --squash-all context/ --tag community-ansible-dev-tools-base:latest
+    podman build --squash-all final/ --tag community-ansible-dev-tools:test
     pytest --only-container --image-name community-ansible-dev-tools:test
 allowlist_externals =
     podman