Configuration

The CLI and both MCP transports share the same startup configuration. Choose a file for local work, environment injection for containers, and flags for explicit per-process overrides.

Precedence

Values are applied in this order, with later layers taking priority:

Built-in defaults → optional dotenv file → process environment → CLI flags

The default file is .env in the current working directory. Parent directories are not searched. A missing default file is allowed; an unreadable or malformed file fails startup without printing its contents.

mcp-gmap-rs --env-file /etc/mcp-gmap/runtime.env serve http
mcp-gmap-rs --no-env-file tools

MCP_ENV_FILE selects a file too, while --env-file takes precedence. An explicitly selected file must exist. --no-env-file disables file loading, including MCP_ENV_FILE; it conflicts with --env-file. Dotenv parsing does not mutate the process environment.

Override a mounted configuration

GOOGLE_MAPS_LANGUAGE=en
GOOGLE_MAPS_TIMEOUT=30
GOOGLE_MAPS_ENABLED_TOOLS=maps_search_places,maps_place_details

With that file mounted, an environment variable changes the language and a flag changes the timeout:

GOOGLE_MAPS_LANGUAGE=fr mcp-gmap-rs \
  --env-file /etc/mcp-gmap/runtime.env --timeout 15 tools

Repeated --allowed-host and --allowed-origin flags replace their corresponding file/environment lists as a whole. An explicitly empty environment value also overrides the file: it can clear an optional token or list, while an empty timeout is invalid.

Control the tool surface

GOOGLE_MAPS_ENABLED_TOOLS or --enabled-tools accepts comma-separated logical names such as maps_weather,maps_air_quality, or * for all tools. Unknown names fail startup. Disabled tools disappear from discovery and cannot be called. Discovery and schema inspection need no credentials, but a requested API operation must have the appropriate Google credential.

Application settings are read at startup. Restart after changing environment values, credential JSON or Kubernetes Secret/ConfigMap configuration. Native TLS certificate, key and client-CA files are the exception: they support SIGHUP reload.

See the complete configuration reference for all 21 settings, defaults, flags and ranges. Website language selection does not change GOOGLE_MAPS_LANGUAGE, which controls Google response text.