🛡️ mcp-secret-launcher

Stop leaking API tokens! Secure your MCP servers by fetching secrets from your OS keyring instead of storing them in plaintext mcp.json.

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🚀 Why Use This?

MCP server configurations typically require sensitive tokens in plaintext env blocks. This makes them visible to anyone with file access and easy to accidentally commit. mcp-secret-launcher solves this by:

• 🔒 Keyring Integration: Uses GNOME Keyring (Linux), Keychain (macOS), or Credential Manager (Windows).
• 🔑 AWS SSO Support: Automatically handles AWS SSO login and injects temporary credentials.
• 💨 Zero overhead: Replaces itself with the target process via execvp on Unix.
• 🛠️ Seamless Integration: Works with any MCP client (Kiro, VS Code, etc.) with a simple one-line change.

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⚡ Quick Start

1. Install

cargo build --release
cp target/release/mcp-secret-launcher ~/.local/bin/

2. Store a Secret

mcp-secret-launcher set --profile my-server --key API_KEY
# Enter secret value: [secure input]

3. Update mcp.json

Update your server configuration to use the launcher:

 {
   "mcpServers": {
     "my-server": {
-      "command": "uvx",
-      "args": ["my-server-command"],
-      "env": { "API_KEY": "YOUR_SECRET_IN_PLAINTEXT" }
+      "command": "mcp-secret-launcher",
+      "args": ["run", "--profile", "my-server", "--", "uvx", "my-server-command"],
+      "env": { "NON_SECRET_VAR": "public-value" }
     }
   }
 }

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🌟 Key Features

🔐 Platform Native Security

No new databases or config files. We use what's already on your machine:

• Linux: Secret Service API (via DBus)
• macOS: Apple Keychain
• Windows: Windows Credential Manager

☁️ AWS SSO Magic

Launching an AWS-based MCP server? Tired of manual aws sso login?

mcp-secret-launcher aws-auth \
  --sso-url https://my-sso.awsapps.com/start \
  --region us-east-1 \
  --account-id 123456789012 \
  --role-name DeveloperRole \
  -- uvx mcp-server-aws

The launcher will handle the browser-based auth flow and inject AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, etc., directly into the server's memory.

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🛡️ Defense in Depth

For maximum security, combine mcp-secret-launcher with mcp-guard:

• mcp-secret-launcher (Layer 3/4): Protects your credentials by keeping them in the OS keyring.
• mcp-guard (Layer 7): Protects your resources by intercepting tool calls and enforcing Human-In-The-Loop (HITL) approval.

Complete Security Stack:

"my-server": {
  "command": "mcp-guard",
  "args": [
    "--policy", "guard-policy.toml",
    "--",
    "mcp-secret-launcher", "run", "--profile", "my-server",
    "--",
    "uvx", "my-server-command"
  ]
}

In this setup, mcp-guard acts as the primary proxy, and mcp-secret-launcher initializes the environment before the server starts.

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📖 Learn More

Guide	Description
📂 Usage Guide	Detailed CLI commands and mcp.json examples.
🏗️ Architecture	How the secret injection and process replacement works.
👩‍💻 Development	Setup instructions for contributors.

⚖️ License

Distributed under the MIT License. See LICENSE for more information.