# Proxy Support for MCP Servers

## Overview

MCPHub supports configuring proxy servers for MCP servers that need to access external resources through a proxy. This is particularly useful when:

- Your MCP servers need to install packages from external repositories
- Your network environment requires proxy for internet access
- You need to route MCP server traffic through a specific proxy

## How It Works

For **stdio-based MCP servers** (servers that spawn child processes), MCPHub automatically passes environment variables to the spawned process. This includes standard proxy environment variables:

- `HTTP_PROXY` / `http_proxy` - Proxy server for HTTP connections
- `HTTPS_PROXY` / `https_proxy` - Proxy server for HTTPS connections
- `NO_PROXY` / `no_proxy` - Comma-separated list of hosts that should bypass the proxy

## Configuration Methods

### Method 1: System-wide Environment Variables

Set proxy environment variables before starting MCPHub. These will be inherited by all MCP servers:

```bash
# Linux/macOS
export HTTP_PROXY="http://proxy.example.com:8080"
export HTTPS_PROXY="http://proxy.example.com:8080"
export NO_PROXY="localhost,127.0.0.1,.local"

# Start MCPHub
npm start
```

```powershell
# Windows PowerShell
$env:HTTP_PROXY="http://proxy.example.com:8080"
$env:HTTPS_PROXY="http://proxy.example.com:8080"
$env:NO_PROXY="localhost,127.0.0.1,.local"

# Start MCPHub
npm start
```

### Method 2: Per-Server Configuration

Configure proxy settings for specific MCP servers in `mcp_settings.json`:

```json
{
  "mcpServers": {
    "my-server": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-example"],
      "env": {
        "HTTP_PROXY": "http://proxy.example.com:8080",
        "HTTPS_PROXY": "http://proxy.example.com:8080",
        "NO_PROXY": "localhost,127.0.0.1"
      }
    }
  }
}
```

### Method 3: Using Environment Variable References

Combine per-server configuration with environment variable references for flexibility:

```json
{
  "mcpServers": {
    "my-server": {
      "type": "stdio",
      "command": "uvx",
      "args": ["mcp-server-fetch"],
      "env": {
        "HTTP_PROXY": "${COMPANY_HTTP_PROXY}",
        "HTTPS_PROXY": "${COMPANY_HTTPS_PROXY}",
        "NO_PROXY": "${COMPANY_NO_PROXY}"
      }
    }
  }
}
```

Then set the environment variables:

```bash
export COMPANY_HTTP_PROXY="http://proxy.example.com:8080"
export COMPANY_HTTPS_PROXY="http://proxy.example.com:8080"
export COMPANY_NO_PROXY="localhost,127.0.0.1,.local"
```

## Docker Usage

### Method 1: Docker Environment Variables

Pass proxy settings when running MCPHub container:

```bash
docker run \
  -e HTTP_PROXY="http://proxy.example.com:8080" \
  -e HTTPS_PROXY="http://proxy.example.com:8080" \
  -e NO_PROXY="localhost,127.0.0.1" \
  -v $(pwd)/mcp_settings.json:/app/mcp_settings.json \
  samanhappy/mcphub:latest
```

### Method 2: Docker Compose

Configure proxy in `docker-compose.yml`:

```yaml
version: '3.8'
services:
  mcphub:
    image: samanhappy/mcphub:latest
    environment:
      - HTTP_PROXY=http://proxy.example.com:8080
      - HTTPS_PROXY=http://proxy.example.com:8080
      - NO_PROXY=localhost,127.0.0.1,.local
    volumes:
      - ./mcp_settings.json:/app/mcp_settings.json
```

### Method 3: Docker Environment File

Create a `.env` file:

```bash
# .env
HTTP_PROXY=http://proxy.example.com:8080
HTTPS_PROXY=http://proxy.example.com:8080
NO_PROXY=localhost,127.0.0.1,.local
```

Use it with Docker:

```bash
docker run --env-file .env -v $(pwd)/mcp_settings.json:/app/mcp_settings.json samanhappy/mcphub:latest
```

Or with docker-compose.yml:

```yaml
version: '3.8'
services:
  mcphub:
    image: samanhappy/mcphub:latest
    env_file:
      - .env
    volumes:
      - ./mcp_settings.json:/app/mcp_settings.json
```

## Examples

### Example 1: NPM Packages with Proxy

Configure an MCP server that uses NPM packages through a proxy:

```json
{
  "mcpServers": {
    "playwright-server": {
      "type": "stdio",
      "command": "npx",
      "args": ["@playwright/mcp@latest", "--headless"],
      "env": {
        "HTTP_PROXY": "http://proxy.company.com:8080",
        "HTTPS_PROXY": "http://proxy.company.com:8080",
        "NO_PROXY": "localhost,127.0.0.1,.company.com"
      }
    }
  }
}
```

### Example 2: Python UVX with Proxy

Configure a Python-based MCP server that needs proxy for package installation:

```json
{
  "mcpServers": {
    "fetch-server": {
      "type": "stdio",
      "command": "uvx",
      "args": ["mcp-server-fetch"],
      "env": {
        "HTTP_PROXY": "http://proxy.company.com:8080",
        "HTTPS_PROXY": "http://proxy.company.com:8080",
        "NO_PROXY": "localhost,127.0.0.1,*.internal"
      }
    }
  }
}
```

### Example 3: Mixed Configuration

Some servers use proxy, others don't:

```json
{
  "mcpServers": {
    "external-api": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@external/mcp-server"],
      "env": {
        "HTTP_PROXY": "${EXTERNAL_PROXY}",
        "HTTPS_PROXY": "${EXTERNAL_PROXY}"
      }
    },
    "internal-service": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@internal/mcp-server"],
      "env": {
        "NO_PROXY": "*"
      }
    }
  }
}
```

## Proxy Authentication

If your proxy requires authentication, include credentials in the proxy URL:

```json
{
  "mcpServers": {
    "my-server": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "my-mcp-server"],
      "env": {
        "HTTP_PROXY": "http://username:password@proxy.example.com:8080",
        "HTTPS_PROXY": "http://username:password@proxy.example.com:8080"
      }
    }
  }
}
```

**Security Note**: For better security, use environment variable references to avoid storing credentials in configuration files:

```json
{
  "mcpServers": {
    "my-server": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "my-mcp-server"],
      "env": {
        "HTTP_PROXY": "${PROXY_URL_WITH_CREDENTIALS}"
      }
    }
  }
}
```

Then set the environment variable:

```bash
export PROXY_URL_WITH_CREDENTIALS="http://username:password@proxy.example.com:8080"
```

## Troubleshooting

### Proxy Not Working

1. **Verify proxy configuration**:
   ```bash
   echo $HTTP_PROXY
   echo $HTTPS_PROXY
   ```

2. **Check proxy connectivity**:
   ```bash
   curl -x http://proxy.example.com:8080 https://www.google.com
   ```

3. **Test with a simple command**:
   ```bash
   HTTP_PROXY=http://proxy.example.com:8080 curl https://api.github.com
   ```

4. **Check MCP server logs**:
   - Look for connection errors in MCPHub console output
   - Check if the MCP server reports proxy-related errors

### Certificate Issues

If using HTTPS proxy with self-signed certificates:

```json
{
  "mcpServers": {
    "my-server": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "my-mcp-server"],
      "env": {
        "HTTPS_PROXY": "http://proxy.example.com:8080",
        "NODE_TLS_REJECT_UNAUTHORIZED": "0"
      }
    }
  }
}
```

**Warning**: Disabling certificate validation (`NODE_TLS_REJECT_UNAUTHORIZED=0`) should only be used in development or trusted networks.

### Proxy for Package Installation Only

If you only need proxy for package installation (not runtime):

For NPM:
```bash
npm config set proxy http://proxy.example.com:8080
npm config set https-proxy http://proxy.example.com:8080
```

For Python/UV:
```bash
export UV_HTTP_PROXY=http://proxy.example.com:8080
```

## Limitations

### SSE and HTTP-based MCP Servers

The proxy configuration described here applies to **stdio-based MCP servers** (servers that spawn child processes).

For **SSE** or **HTTP-based** MCP servers, MCPHub itself acts as the HTTP client. In these cases:

1. Set proxy environment variables for the MCPHub process (not in `mcp_settings.json`)
2. The Node.js HTTP client will automatically use these proxy settings

Example for SSE servers:

```bash
# Set proxy for MCPHub process
export HTTP_PROXY="http://proxy.example.com:8080"
export HTTPS_PROXY="http://proxy.example.com:8080"

# Start MCPHub - it will use these settings for SSE/HTTP connections
npm start
```

## Best Practices

1. **Use environment variables** for proxy credentials to avoid storing them in configuration files
2. **Configure NO_PROXY** to exclude internal services and localhost
3. **Test proxy configuration** before deploying to production
4. **Document proxy requirements** for your deployment environment
5. **Use separate proxy configurations** for different MCP servers when needed
6. **Monitor proxy logs** for connection issues and performance

## Related Documentation

- [Environment Variables](../environment-variables.md) - Learn about environment variable expansion
- [Docker Setup](./docker-setup.mdx) - Docker-specific configuration
- [MCP Settings](./mcp-settings.mdx) - Complete configuration reference