cowboy:get_env(3)

Name

cowboy:get_env - Retrieve a listener's environment value

Description

get_env(Name :: ranch:ref(),
        Key  :: atom())
    -> any()

get_env(Name    :: ranch:ref(),
        Key     :: atom(),
        Default :: any())
    -> any()

Retrieve an environment value for a previously started listener.

This function may crash when the key is missing from the environment and a default value is not provided.

Arguments

Name

The name of the listener to access.

The name of the listener is the first argument given to the cowboy:start_clear(3), cowboy:start_tls(3) or ranch:start_listener(3) function.

Key

The key in the environment map. Common keys include dispatch and middlewares.

Default

The default value if the key is missing.

Return value

The environment value is returned on success.

If a default was provided and the key is missing, then the default value is returned.

An exit:badarg exception is thrown when the listener does not exist.

An exit:{badkey, Key} exception is thrown when the key requested is missing and no default was provided.

Changelog

• 2.11: Function introduced.

Examples

Dispatch = cowboy:get_env(example, dispatch).

See also

cowboy(3), cowboy:start_clear(3), cowboy:start_tls(3), cowboy:set_env(3), ranch:get_protocol_options(3)