Use isolated docker config in test sandbox (#700)

* Introduce DOCKER_CONFIG_FILE in test-suite

* Set DOCKER_CONFIG_FILE in CI

---------

Co-authored-by: Frederik Ring <frederik.ring@gmail.com>

.github/workflows/test.yml

@@ -23,6 +23,8 @@ jobs:
         uses: docker/setup-buildx-action@v2
 
       - name: Run Tests
+        env:
+          DOCKER_CONFIG_FILE: /home/runner/.docker/config.json
         working-directory: ./test
         run: |
           BUILD_IMAGE=1 ./test.sh

test/README.md

@@ -41,6 +41,15 @@ IMAGE_TAG=v2.30.0 ./test.sh
 
 By default, two local images are created that persist the image data and provide it to containers at runtime.
 
+#### `DOCKER_CONFIG_FILE`
+
+By default, the sandbox uses an empty Docker config file (`./docker-config.json`).
+To use host credentials (e.g. in CI), set `DOCKER_CONFIG_FILE` to the desired `config.json` location:
+
+```sh
+DOCKER_CONFIG_FILE=${HOME}/.docker/config.json ./test.sh
+```
+
 ## Understanding the test setup
 
 The test setup runs each test case in an isolated Docker container, which itself is running an otherwise unused Docker daemon.

test/docker-compose.yml

@@ -10,7 +10,7 @@ services:
       retries: 50
     volumes:
       - ./:/code
-      - ${HOME}/.docker/config.json:/root/.docker/config.json
+      - ${DOCKER_CONFIG_FILE:-./docker-config.json}:/root/.docker/config.json
       - ${TARBALL:-.}:/cache/image.tar.gz
       - docker_volume_backup_test_sandbox_image:/var/lib/docker/image
       - docker_volume_backup_test_sandbox_containerd:/var/lib/docker/containerd
@@ -20,7 +20,7 @@ services:
     hostname: worker1
     volumes:
       - ./:/code
-      - ${HOME}/.docker/config.json:/root/.docker/config.json
+      - ${DOCKER_CONFIG_FILE:-./docker-config.json}:/root/.docker/config.json
       - ${TARBALL:-.}:/cache/image.tar.gz
       - docker_volume_backup_test_sandbox_image:/var/lib/docker/image
       - docker_volume_backup_test_sandbox_containerd_1:/var/lib/docker/containerd
@@ -31,7 +31,7 @@ services:
     hostname: worker2
     volumes:
       - ./:/code
-      - ${HOME}/.docker/config.json:/root/.docker/config.json
+      - ${DOCKER_CONFIG_FILE:-./docker-config.json}:/root/.docker/config.json
       - ${TARBALL:-.}:/cache/image.tar.gz
       - docker_volume_backup_test_sandbox_image:/var/lib/docker/image
       - docker_volume_backup_test_sandbox_containerd_2:/var/lib/docker/containerd

test/docker-config.json

@@ -0,0 +1 @@
+{}