chore: create unregistry-dind image for testing

Author: psviderski

.dockerignore

@@ -4,6 +4,7 @@
 # Allow files and directories.
 !cmd/
 !internal/
+!scripts/
 !go.*
 
 # Ignore unnecessary files inside allowed directories.

Dockerfile

@@ -12,13 +12,25 @@ COPY . .
 RUN GOOS=${TARGETOS} GOARCH=${TARGETARCH} go build -o unregistry ./cmd/unregistry
 
 
+# Unregistry in Docker-in-Docker image for e2e tests.
+FROM docker:28.2.2-dind AS unregistry-dind
+
+ENV UNREGISTRY_CONTAINERD_SOCK="/run/docker/containerd/containerd.sock"
+
+COPY scripts/dind-entrypoint.sh /usr/local/bin/entrypoint.sh
+COPY --from=builder /build/unregistry /usr/local/bin/
+
+EXPOSE 5000
+ENTRYPOINT ["entrypoint.sh"]
+CMD ["unregistry"]
+
 # Create a minimal image with the static binary built in the builder stage.
 FROM alpine:${ALPINE_VERSION}
 
-# TODO: remove when migrated to containerd storage.
-RUN mkdir -p /var/lib/unregistry
-
 COPY --from=builder /build/unregistry /usr/local/bin/
+
+EXPOSE 5000
 # Run as root user by default to allow access to the containerd socket. This in unfortunate as running as non-root user
 # requires changing the containerd socket permissions which still can be manually done by advanced users.
 ENTRYPOINT ["unregistry"]
+

scripts/dind-entrypoint.sh

@@ -0,0 +1,36 @@
+#!/bin/sh
+set -eu
+
+# Cleanup function to properly terminate background processes.
+cleanup() {
+    echo "Terminating container processes..."
+
+    # Terminate the main process if it has been started.
+    if [ -n "${MAIN_PID:-}" ]; then
+        kill "$MAIN_PID" 2>/dev/null || true
+    fi
+
+    # Terminate Docker daemon if PID file exists.
+    if [ -f /run/docker.pid ]; then
+        kill "$(cat /run/docker.pid)" 2>/dev/null || true
+    fi
+
+    # Wait for processes to terminate.
+    wait
+}
+trap cleanup INT TERM EXIT
+
+if [ "${DOCKER_CONTAINERD_STORE:-true}" = "true" ]; then
+    echo "Using containerd image store for Docker."
+    mkdir -p /etc/docker
+    echo '{"features": {"containerd-snapshotter": true}}' > /etc/docker/daemon.json
+else
+    echo "Using the default Docker image store."
+fi
+
+dind dockerd --host=tcp://0.0.0.0:2375 --tls=false &
+
+# Execute the passed command and wait for it while maintaining signal handling.
+"$@" &
+MAIN_PID=$!
+wait $MAIN_PID