Content
# OpenAPI-MCP: Dockerized MCP Server to allow your AI agent to access any API with existing api docs
[](https://pkg.go.dev/github.com/ckanthony/openapi-mcp)
[](https://github.com/ckanthony/openapi-mcp/actions/workflows/ci.yml)
[](https://codecov.io/gh/ckanthony/openapi-mcp)
**Generate MCP tool definitions directly from a Swagger/OpenAPI specification file.**
OpenAPI-MCP is a dockerized MCP server that reads a `swagger.json` or `openapi.yaml` file and generates a corresponding [Model Context Protocol (MCP)](https://modelcontextprotocol.io/introduction) toolset. This allows MCP-compatible clients like [Cursor](https://cursor.sh/) to interact with APIs described by standard OpenAPI specifications. Now you can enable your AI agent to access any API by simply providing its OpenAPI/Swagger specification - no additional coding required.
## Table of Contents
- [Why OpenAPI-MCP?](#why-openapi-mcp)
- [Features](#features)
- [Installation](#installation)
- [Using the Pre-built Docker Hub Image (Recommended)](#using-the-pre-built-docker-hub-image-recommended)
- [Building Locally (Optional)](#building-locally-optional)
- [Running the Weatherbit Example (Step-by-Step)](#running-the-weatherbit-example-step-by-step)
- [Command-Line Options](#command-line-options)
- [Environment Variables](#environment-variables)
## Demo
Run the demo yourself: [Running the Weatherbit Example (Step-by-Step)](#running-the-weatherbit-example-step-by-step)
## Why OpenAPI-MCP?
- **Standard Compliance:** Leverage your existing OpenAPI/Swagger documentation.
- **Automatic Tool Generation:** Create MCP tools without manual configuration for each endpoint.
- **Flexible API Key Handling:** Securely manage API key authentication for the proxied API without exposing keys to the MCP client.
- **Local & Remote Specs:** Works with local specification files or remote URLs.
- **Dockerized Tool:** Easily deploy and run as a containerized service with Docker.
## Features
- **OpenAPI v2 (Swagger) & v3 Support:** Parses standard specification formats.
- **Schema Generation:** Creates MCP tool schemas from OpenAPI operation parameters and request/response definitions.
- **Secure API Key Management:**
- Injects API keys into requests (`header`, `query`, `path`, `cookie`) based on command-line configuration.
- Loads API keys directly from flags (`--api-key`), environment variables (`--api-key-env`), or `.env` files located alongside local specs.
- Keeps API keys hidden from the end MCP client (e.g., the AI assistant).
- **Server URL Detection:** Uses server URLs from the spec as the base for tool interactions (can be overridden).
- **Filtering:** Options to include/exclude specific operations or tags (`--include-tag`, `--exclude-tag`, `--include-op`, `--exclude-op`).
- **Request Header Injection:** Pass custom headers (e.g., for additional auth, tracing) via the `REQUEST_HEADERS` environment variable.
## Installation
### Docker
The recommended way to run this tool is via [Docker](https://hub.docker.com/r/ckanthony/openapi-mcp).
#### Using the Pre-built Docker Hub Image (Recommended)
Alternatively, you can use the pre-built image available on [Docker Hub](https://hub.docker.com/r/ckanthony/openapi-mcp).
1. **Pull the Image:**
```bash
docker pull ckanthony/openapi-mcp:latest
```
2. **Run the Container:**
Follow the `docker run` examples above, but replace `openapi-mcp:latest` with `ckanthony/openapi-mcp:latest`.
#### Building Locally (Optional)
1. **Build the Docker Image Locally:**
```bash
# Navigate to the repository root
cd openapi-mcp
# Build the Docker image (tag it as you like, e.g., openapi-mcp:latest)
docker build -t openapi-mcp:latest .
```
2. **Run the Container:**
You need to provide the OpenAPI specification and any necessary API key configuration when running the container.
* **Example 1: Using a local spec file and `.env` file:**
- Create a directory (e.g., `./my-api`) containing your `openapi.json` or `swagger.yaml`.
- If the API requires a key, create a `.env` file in the *same directory* (e.g., `./my-api/.env`) with `API_KEY=your_actual_key` (replace `API_KEY` if your `--api-key-env` flag is different).
```bash
docker run -p 8080:8080 --rm \\
-v $(pwd)/my-api:/app/spec \\
--env-file $(pwd)/my-api/.env \\
openapi-mcp:latest \\
--spec /app/spec/openapi.json \\
--api-key-env API_KEY \\
--api-key-name X-API-Key \\
--api-key-loc header
```
*(Adjust `--spec`, `--api-key-env`, `--api-key-name`, `--api-key-loc`, and `-p` as needed.)*
* **Example 2: Using a remote spec URL and direct environment variable:**
```bash
docker run -p 8080:8080 --rm \\
-e SOME_API_KEY="your_actual_key" \\
openapi-mcp:latest \\
--spec https://petstore.swagger.io/v2/swagger.json \\
--api-key-env SOME_API_KEY \\
--api-key-name api_key \\
--api-key-loc header
```
* **Key Docker Run Options:**
* `-p <host_port>:8080`: Map a port on your host to the container's default port 8080.
* `--rm`: Automatically remove the container when it exits.
* `-v <host_path>:<container_path>`: Mount a local directory containing your spec into the container. Use absolute paths or `$(pwd)/...`. Common container path: `/app/spec`.
* `--env-file <path_to_host_env_file>`: Load environment variables from a local file (for API keys, etc.). Path is on the host.
* `-e <VAR_NAME>="<value>"`: Pass a single environment variable directly.
* `openapi-mcp:latest`: The name of the image you built locally.
* `--spec ...`: **Required.** Path to the spec file *inside the container* (e.g., `/app/spec/openapi.json`) or a public URL.
* `--port 8080`: (Optional) Change the internal port the server listens on (must match the container port in `-p`).
* `--api-key-env`, `--api-key-name`, `--api-key-loc`: Required if the target API needs an API key.
* (See `--help` for all command-line options by running `docker run --rm openapi-mcp:latest --help`)
## Running the Weatherbit Example (Step-by-Step)
This repository includes an example using the [Weatherbit API](https://www.weatherbit.io/). Here's how to run it using the public Docker image:
1. **Find OpenAPI Specs (Optional Knowledge):**
Many public APIs have their OpenAPI/Swagger specifications available online. A great resource for discovering them is [APIs.guru](https://apis.guru/). The Weatherbit specification used in this example (`weatherbitio-swagger.json`) was sourced from there.
2. **Get a Weatherbit API Key:**
* Go to [Weatherbit.io](https://www.weatherbit.io/) and sign up for an account (they offer a free tier).
* Find your API key in your Weatherbit account dashboard.
3. **Clone this Repository:**
You need the example files from this repository.
```bash
git clone https://github.com/ckanthony/openapi-mcp.git
cd openapi-mcp
```
4. **Prepare Environment File:**
* Navigate to the example directory: `cd example/weather`
* Copy the example environment file: `cp .env.example .env`
* Edit the new `.env` file and replace `YOUR_WEATHERBIT_API_KEY_HERE` with the actual API key you obtained from Weatherbit.
5. **Run the Docker Container:**
From the `openapi-mcp` **root directory** (the one containing the `example` folder), run the following command:
```bash
docker run -p 8080:8080 --rm \\
-v $(pwd)/example/weather:/app/spec \\
--env-file $(pwd)/example/weather/.env \\
ckanthony/openapi-mcp:latest \\
--spec /app/spec/weatherbitio-swagger.json \\
--api-key-env API_KEY \\
--api-key-name key \\
--api-key-loc query
```
* `-v $(pwd)/example/weather:/app/spec`: Mounts the local `example/weather` directory (containing the spec and `.env` file) to `/app/spec` inside the container.
* `--env-file $(pwd)/example/weather/.env`: Tells Docker to load environment variables (specifically `API_KEY`) from your `.env` file.
* `ckanthony/openapi-mcp:latest`: Uses the public Docker image.
* `--spec /app/spec/weatherbitio-swagger.json`: Points to the spec file inside the container.
* The `--api-key-*` flags configure how the tool should inject the API key (read from the `API_KEY` env var, named `key`, placed in the `query` string).
6. **Access the MCP Server:**
The MCP server should now be running and accessible at `http://localhost:8080` for compatible clients.
**Using Docker Compose (Example):**
A `docker-compose.yml` file is provided in the `example/` directory to demonstrate running the Weatherbit API example using the *locally built* image.
1. **Prepare Environment File:** Copy `example/weather/.env.example` to `example/weather/.env` and add your actual Weatherbit API key:
```dotenv
# example/weather/.env
API_KEY=YOUR_ACTUAL_WEATHERBIT_KEY
```
2. **Run with Docker Compose:** Navigate to the `example` directory and run:
```bash
cd example
# This builds the image locally based on ../Dockerfile
# It does NOT use the public Docker Hub image
docker-compose up --build
```
* `--build`: Forces Docker Compose to build the image using the `Dockerfile` in the project root before starting the service.
* Compose will read `example/docker-compose.yml`, build the image, mount `./weather`, read `./weather/.env`, and start the `openapi-mcp` container with the specified command-line arguments.
* The MCP server will be available at `http://localhost:8080`.
3. **Stop the service:** Press `Ctrl+C` in the terminal where Compose is running, or run `docker-compose down` from the `example` directory in another terminal.
## Command-Line Options
The `openapi-mcp` command accepts the following flags:
| Flag | Description | Type | Default |
|----------------------|---------------------------------------------------------------------------------------------------------------------|---------------|----------------------------------|
| `--spec` | **Required.** Path or URL to the OpenAPI specification file. | `string` | (none) |
| `--port` | Port to run the MCP server on. | `int` | `8080` |
| `--api-key` | Direct API key value (use `--api-key-env` or `.env` file instead for security). | `string` | (none) |
| `--api-key-env` | Environment variable name containing the API key. If spec is local, also checks `.env` file in the spec's directory. | `string` | (none) |
| `--api-key-name` | **Required if key used.** Name of the API key parameter (header, query, path, or cookie name). | `string` | (none) |
| `--api-key-loc` | **Required if key used.** Location of API key: `header`, `query`, `path`, or `cookie`. | `string` | (none) |
| `--include-tag` | Tag to include (can be repeated). If include flags are used, only included items are exposed. | `string slice`| (none) |
| `--exclude-tag` | Tag to exclude (can be repeated). Exclusions apply after inclusions. | `string slice`| (none) |
| `--include-op` | Operation ID to include (can be repeated). | `string slice`| (none) |
| `--exclude-op` | Operation ID to exclude (can be repeated). | `string slice`| (none) |
| `--base-url` | Manually override the target API server base URL detected from the spec. | `string` | (none) |
| `--name` | Default name for the generated MCP toolset (used if spec has no title). | `string` | "OpenAPI-MCP Tools" |
| `--desc` | Default description for the generated MCP toolset (used if spec has no description). | `string` | "Tools generated from OpenAPI spec" |
**Note:** You can get this list by running the tool with the `--help` flag (e.g., `docker run --rm ckanthony/openapi-mcp:latest --help`).
### Environment Variables
* `REQUEST_HEADERS`: Set this environment variable to a JSON string (e.g., `'{"X-Custom": "Value"}'`) to add custom headers to *all* outgoing requests to the target API.
