fix: respect NODE_DB_PATH environment variable in Docker (fixes #40)

- Fixed docker-entrypoint.sh to use NODE_DB_PATH instead of hardcoded paths
- Added log_message() helper to prevent stdio mode output corruption
- Fixed directory creation race condition with proper ownership
- Added path validation to ensure NODE_DB_PATH ends with .db
- Updated rebuild.ts to respect NODE_DB_PATH environment variable
- Added comprehensive documentation for custom database paths
- Bumped version to 2.7.16

The bug was caused by hardcoded /app/data/nodes.db paths in the Docker
entrypoint script that ignored the NODE_DB_PATH environment variable.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

docs/DOCKER_README.md

@@ -64,6 +64,7 @@ docker run -d \
 | `PORT` | HTTP server port | `3000` | No |
 | `NODE_ENV` | Environment: `development` or `production` | `production` | No |
 | `LOG_LEVEL` | Logging level: `debug`, `info`, `warn`, `error` | `info` | No |
+| `NODE_DB_PATH` | Custom database path (v2.7.16+) | `/app/data/nodes.db` | No |
 
 *Either `AUTH_TOKEN` or `AUTH_TOKEN_FILE` must be set for HTTP mode. If both are set, `AUTH_TOKEN` takes precedence.
 
@@ -342,6 +343,28 @@ docker run --rm \
   alpine tar xzf /backup/n8n-mcp-backup.tar.gz -C /target
 ```
 
+### Custom Database Path (v2.7.16+)
+
+You can specify a custom database location using `NODE_DB_PATH`:
+
+```bash
+# Use custom path within mounted volume
+docker run -d \
+  --name n8n-mcp \
+  -e MCP_MODE=http \
+  -e AUTH_TOKEN=your-token \
+  -e NODE_DB_PATH=/app/data/custom/my-nodes.db \
+  -v n8n-mcp-data:/app/data \
+  -p 3000:3000 \
+  ghcr.io/czlonkowski/n8n-mcp:latest
+```
+
+**Important Notes:**
+- The path must end with `.db`
+- For data persistence, ensure the path is within a mounted volume
+- Paths outside mounted volumes will be lost on container restart
+- The directory will be created automatically if it doesn't exist
+
 ## 🐛 Troubleshooting
 
 ### Common Issues
@@ -506,4 +529,4 @@ services:
 
 ---
 
-*Last updated: June 2025 - Docker implementation v1.0*
+*Last updated: July 2025 - Docker implementation v1.1*

docs/DOCKER_TROUBLESHOOTING.md

@@ -5,6 +5,7 @@ This guide helps resolve common issues when running n8n-mcp with Docker, especia
 ## Table of Contents
 - [Common Issues](#common-issues)
   - [502 Bad Gateway Errors](#502-bad-gateway-errors)
+  - [Custom Database Path Not Working](#custom-database-path-not-working-v27160)
   - [Container Name Conflicts](#container-name-conflicts)
   - [n8n API Connection Issues](#n8n-api-connection-issues)
 - [Docker Networking](#docker-networking)
@@ -13,6 +14,41 @@ This guide helps resolve common issues when running n8n-mcp with Docker, especia
 
 ## Common Issues
 
+### Custom Database Path Not Working (v2.7.16+)
+
+**Symptoms:**
+- `NODE_DB_PATH` environment variable is set but ignored
+- Database always created at `/app/data/nodes.db`
+- Custom path setting has no effect
+
+**Root Cause:** Fixed in v2.7.16. Earlier versions had hardcoded paths in docker-entrypoint.sh.
+
+**Solutions:**
+
+1. **Update to v2.7.16 or later:**
+```bash
+docker pull ghcr.io/czlonkowski/n8n-mcp:latest
+```
+
+2. **Ensure path ends with .db:**
+```bash
+# Correct
+NODE_DB_PATH=/app/data/custom/my-nodes.db
+
+# Incorrect (will be rejected)
+NODE_DB_PATH=/app/data/custom/my-nodes
+```
+
+3. **Use path within mounted volume for persistence:**
+```yaml
+services:
+  n8n-mcp:
+    environment:
+      NODE_DB_PATH: /app/data/custom/nodes.db
+    volumes:
+      - n8n-mcp-data:/app/data  # Ensure parent directory is mounted
+```
+
 ### 502 Bad Gateway Errors
 
 **Symptoms:**