Add integration test for directly running the shim with docker

tests/docker-integration-test/Dockerfile.dind-containerd-spin-shim

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+ARG DOCKER_VERSION=27
+FROM docker:${DOCKER_VERSION}-dind
+
+ARG CONTAINERD_SPIN_SHIM_VERSION=v0.22.0
+ARG SHIM_FILE=""
+
+# Enable the containerd snapshotter
+RUN mkdir -p /etc/docker && \
+    echo '{ \
+  "features": { \
+    "containerd-snapshotter": true \
+  } \
+}' > /etc/docker/daemon.json
+
+# Download or use copied shim
+RUN apk add --no-cache curl && \
+    if [ -n "${SHIM_FILE}" ]; then \
+      echo "Will use local shim file..."; \
+    else \
+      echo "Downloading shim version ${CONTAINERD_SPIN_SHIM_VERSION}..." && \
+      curl -LRO https://github.com/spinframework/containerd-shim-spin/releases/download/${CONTAINERD_SPIN_SHIM_VERSION}/containerd-shim-spin-v2-linux-x86_64.tar.gz && \
+      tar -xzf containerd-shim-spin-v2-linux-x86_64.tar.gz -C /usr/local/bin/ && \
+      rm containerd-shim-spin-v2-linux-x86_64.tar.gz; \
+    fi
+
+# Expose port for the Spin application
+EXPOSE 8080
+
+CMD ["dockerd-entrypoint.sh"]

tests/docker-integration-test/docker-integration-test.sh

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+#! /bin/bash
+
+set -xeuo pipefail
+
+# Cleanup function
+cleanup() {
+  echo "Cleaning up..."
+  docker rm -f docker-test 2>/dev/null || true
+}
+
+usage() {
+  echo "Usage: $0"
+  echo "Environment variables:"
+  echo "  DOCKER_VERSION - The version of Docker to use (required). Examples: 27, 27.0, 27.0.1, etc"
+  echo "  CONTAINERD_SPIN_SHIM_VERSION - The version of the containerd spin shim to use (optional if SHIM_FILE is set). Example: v0.22.0"
+  echo "  SHIM_FILE - Path to a local containerd spin shim binary (optional if CONTAINERD_SPIN_SHIM_VERSION is set)"
+}
+# Set trap to cleanup on exit (success or failure)
+trap cleanup EXIT
+
+# Require that required environment variables are set
+if [ -z "$DOCKER_VERSION" ]; then
+  echo "Error: DOCKER_VERSION environment variable must be set."
+  exit 1
+fi
+
+# Require that exactly shim path environment variable is set
+if [ -z "${CONTAINERD_SPIN_SHIM_VERSION:-}" ] && [ -z "${SHIM_FILE:-}" ]; then
+  echo "Error: Either CONTAINERD_SPIN_SHIM_VERSION or SHIM_FILE must be set."
+  exit 1
+fi
+
+if [ -n "${SHIM_FILE:-}" ]; then
+  # TODO: figure out how to make this work
+  echo "Using SHIM_FILE at $SHIM_FILE"
+  cp "$SHIM_FILE" "$(dirname "$0")/containerd-shim-spin-v2"
+  SHIM_LOCATION_ARG="SHIM_FILE=containerd-shim-spin-v2"
+else
+  echo "Using CONTAINERD_SPIN_SHIM_VERSION at $CONTAINERD_SPIN_SHIM_VERSION"
+  SHIM_LOCATION_ARG="CONTAINERD_SPIN_SHIM_VERSION=$CONTAINERD_SPIN_SHIM_VERSION"
+fi
+
+docker build \
+    --build-arg $SHIM_LOCATION_ARG \
+    --build-arg DOCKER_VERSION=$DOCKER_VERSION \
+    -t docker-in-docker:$DOCKER_VERSION \
+    -f "$(dirname "$0")/Dockerfile.dind-containerd-spin-shim" .
+
+docker run -d --privileged \
+  --name docker-test \
+  -p 8080:8080 \
+  docker-in-docker:$DOCKER_VERSION
+
+# Wait for Docker to start
+sleep 5
+
+# Your docker exec command with timeout
+if ! timeout 10 docker exec docker-test docker run -d \
+  --name spin \
+  --runtime io.containerd.spin.v2 \
+  --platform wasi/wasm \
+  --publish 8080:80 \
+  ghcr.io/spinframework/containerd-shim-spin/examples/spin-rust-hello:v0.20.0 /; then
+  echo "✗ Failed to start Spin container (timed out or errored)"
+  exit 1
+fi
+
+echo "✓ Spin container started successfully"
+
+sleep 2
+
+# Test the endpoint
+result=$(curl -s localhost:8080/hello)
+if [ "$result" = "Hello world from Spin!" ]; then
+  echo "✓ Test passed: Got expected response"
+else
+  echo "✗ Test failed: Expected 'Hello world from Spin!' but got '$result'"
+fi