# `ReqClientCredentials`
[🔗](https://github.com/jswanner/req_client_credentials/blob/v0.3.1/lib/req_client_credentials.ex#L1)

`Req` plugin for [OAuth 2.0 client credentials flow][rfc] authentication. This
plugin accepts all the options of `Req` itself under the `:client_credentials`
key. The access token will be cached and reused for subsequent requests, if
the response to the authenticated `:url` returns a 401 response then this
plugin will refresh the access token (only refreshes one time). If an
`:audience` is included in `:form` or `:json` option for `:client_credentials`
then this plugin will only run if the host and port of the authenticated
`:url` match that of the `:audience`. The `:url` option within
`:client_credentials` is the URL this plugin will make a POST request to for
creating a bearer token.

[rfc]: https://datatracker.ietf.org/doc/html/rfc6749#section-4.4

# `attach`

Runs the plugin.

## Usage

    Req.new(url: "https://api.example.com/path")
    |> ReqClientCredentials.attach()
    |> Req.get!(
      client_credentials: [
        form: [
          audience: "https://api.example.com",
          client_id: System.get_env("EXAMPLE_CLIENT_ID"),
          client_secret: System.get_env("EXAMPLE_CLIENT_SECRET")
        ],
        url: "https://auth.example.com/oauth/token",
      ]
    )
    #=> %Req.Response{}

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*Consult [api-reference.md](api-reference.md) for complete listing*