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Version: 1.1.x

Environment Variables

MCPX can be configured via environment variables to control logging, authentication, metrics, configuration paths, and runtime behavior.

In order to change the environment variables from the default add the tag -e with the desired variable and updated value. For example, to change LOG_LEVEL to debug and disable metrics, run the following Docker command:

docker run --rm -e LOG_LEVEL=debug -e ENABLE_METRICS=false --pull always --privileged -v ./:/lunar/packages/mcpx-server/config -p 9000:9000 -p 5173:5173 -p 9001:9001 -p 3000:3000 --name mcpx us-central1-docker.pkg.dev/prj-common-442813/mcpx/mcpx:latest

Below is a list of supported variables, their meaning, expected input, and default values.

LOG_LEVEL​

Description: Sets the logging verbosity for MCPX.
Accepted Values: error, warn, info, http, verbose, debug, silly
Default: info

AUTH_KEY​

Description: Optional shared secret used for authenticating incoming connections to MCPX. When set, all requests must include the x-lunar-auth-key header matching this value. This will only be effective if auth.enabled is set to true in app.yaml Accepted Values: Any string
Default: None (authentication is disabled)

MCPX_PORT​

Description: Specifies the port MCPX will bind to for incoming HTTP traffic to MCPX.
Accepted Values: Any valid port number (integer)
Default: 9000

WEBSERVER_PORT​

Description: Sets the host URL of the Lunar AI Gateway MCPX should connect to.
Accepted Values: Any valid URL
Default: http://localhost:9001

ENABLE_METRICS​

Description: Controls whether metrics should be exposed (e.g. for Prometheus scraping).
Accepted Values: true, false (as strings)
Default: true

SERVE_METRICS_PORT​

Description: Defines the port on which MCPX serves its metrics endpoint.
Accepted Values: Any valid port number (integer)
Default: 3000

APP_CONFIG_PATH​

Description: Path to the YAML file containing application-level configuration (e.g., ACLs, rate limits).
Accepted Values: String path to a .yaml file
Default: config/app.yaml

SERVERS_CONFIG_PATH​

Description: Path to the JSON file that defines which MCP servers/tools should be spawned by MCPX.
Accepted Values: String path to a .json file
Default: config/mcp.json

LUNAR_API_KEY​

Description: Lunar.dev API Key used for interception
Accepted Values: API Key
Default: ""