feat: Auto-start Docker daemon when installed in container (#370)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: samanhappy <2755122+samanhappy@users.noreply.github.com>
Co-authored-by: samanhappy <samanhappy@gmail.com>

.github/DOCKER_CLI_TEST.md

@@ -1,6 +1,6 @@
-# Docker CLI Installation Test Procedure
+# Docker Engine Installation Test Procedure
 
-This document describes how to test the Docker CLI installation feature added with the `INSTALL_EXT=true` build argument.
+This document describes how to test the Docker Engine installation feature added with the `INSTALL_EXT=true` build argument.
 
 ## Test 1: Build with INSTALL_EXT=false (default)
 
@@ -12,7 +12,7 @@ docker build -t mcphub:base .
 docker run --rm mcphub:base docker --version
 ```
 
-**Expected Result**: `docker: not found` error (Docker CLI is NOT installed)
+**Expected Result**: `docker: not found` error (Docker is NOT installed)
 
 ## Test 2: Build with INSTALL_EXT=true
 
@@ -26,13 +26,44 @@ docker run --rm mcphub:extended docker --version
 
 **Expected Result**: Docker version output (e.g., `Docker version 27.x.x, build xxxxx`)
 
-## Test 3: Docker-in-Docker Workflow
+## Test 3: Docker-in-Docker with Auto-start Daemon
 
 ```bash
 # Build with extended features
 docker build --build-arg INSTALL_EXT=true -t mcphub:extended .
 
-# Run with Docker socket mounted
+# Run with privileged mode (allows Docker daemon to start)
+docker run -d \
+  --name mcphub-test \
+  --privileged \
+  -p 3000:3000 \
+  mcphub:extended
+
+# Wait a few seconds for daemon to start
+sleep 5
+
+# Test Docker commands from inside the container
+docker exec mcphub-test docker ps
+docker exec mcphub-test docker images
+docker exec mcphub-test docker info
+
+# Cleanup
+docker stop mcphub-test
+docker rm mcphub-test
+```
+
+**Expected Result**: 
+- Docker daemon should auto-start inside the container
+- Docker commands should work without mounting the host's Docker socket
+- `docker info` should show the container's own Docker daemon
+
+## Test 4: Docker-in-Docker with Host Socket (Alternative)
+
+```bash
+# Build with extended features
+docker build --build-arg INSTALL_EXT=true -t mcphub:extended .
+
+# Run with Docker socket mounted (uses host's daemon)
 docker run -d \
   --name mcphub-test \
   -p 3000:3000 \
@@ -48,9 +79,11 @@ docker stop mcphub-test
 docker rm mcphub-test
 ```
 
-**Expected Result**: Docker commands should work and show the host's containers and images
+**Expected Result**: 
+- Docker daemon should NOT auto-start (socket already exists from host)
+- Docker commands should work and show the host's containers and images
 
-## Test 4: Verify Image Size
+## Test 5: Verify Image Size
 
 ```bash
 # Build both versions
@@ -63,9 +96,9 @@ docker images mcphub:*
 
 **Expected Result**: 
 - The `extended` image should be larger than the `base` image
-- The size difference should be reasonable (Docker CLI adds ~60-80MB)
+- The size difference should be reasonable (Docker Engine adds ~100-150MB)
 
-## Test 5: Architecture Support
+## Test 6: Architecture Support
 
 ```bash
 # On AMD64/x86_64
@@ -77,12 +110,15 @@ docker build --build-arg INSTALL_EXT=true --platform linux/arm64 -t mcphub:exten
 
 **Expected Result**: 
 - Both builds should succeed
-- AMD64 includes Chrome/Playwright + Docker CLI
-- ARM64 includes Docker CLI only (Chrome installation is skipped)
+- AMD64 includes Chrome/Playwright + Docker Engine
+- ARM64 includes Docker Engine only (Chrome installation is skipped)
 
 ## Notes
 
-- The Docker CLI installation follows the official Docker documentation
+- The Docker Engine installation follows the official Docker documentation
+- Includes full Docker daemon (`dockerd`), CLI (`docker`), and containerd
+- The daemon auto-starts when running in privileged mode
 - The installation uses the Debian Bookworm repository
 - All temporary files are cleaned up to minimize image size
 - The feature is opt-in via the `INSTALL_EXT` build argument
+- `iptables` is installed as it's required for Docker networking