---
type: docs
title: "OAuth2 client credentials"
linkTitle: "OAuth2 client credentials"
description: "Use OAuth2 client credentials middleware to secure HTTP endpoints"
aliases:
- /developing-applications/middleware/supported-middleware/middleware-oauth2clientcredentials/
---

The OAuth2 client credentials [HTTP middleware]({{% ref middleware.md %}}) enables the [OAuth2 Client Credentials flow](https://tools.ietf.org/html/rfc6749#section-4.4) on a Web API without modifying the application. This design separates authentication/authorization concerns from the application, so that application operators can adopt and configure authentication/authorization providers without impacting the application code.

## Component format

```yaml
apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: oauth2clientcredentials
spec:
  type: middleware.http.oauth2clientcredentials
  version: v1
  metadata:
  - name: clientId
    value: "<your client ID>"
  - name: clientSecret
    value: "<your client secret>"
  - name: scopes
    value: "https://www.googleapis.com/auth/userinfo.email"
  - name: tokenURL
    value: "https://accounts.google.com/o/oauth2/token"
  - name: headerName
    value: "authorization"
  - name: pathFilter
    value: ".*/users/.*"
```

{{% alert title="Warning" color="warning" %}}
The above example uses secrets as plain strings. It is recommended to use a secret store for the secrets as described [here]({{% ref component-secrets.md %}}).
{{% /alert %}}

## Spec metadata fields

| Field      | Details | Example |
|------------|---------|---------|
| clientId | The client ID of your application that is created as part of a credential hosted by a OAuth-enabled platform
| clientSecret | The client secret of your application that is created as part of a credential hosted by a OAuth-enabled platform
| scopes | A list of space-delimited, case-sensitive strings of [scopes](https://tools.ietf.org/html/rfc6749#section-3.3) which are typically used for authorization in the application | `"https://www.googleapis.com/auth/userinfo.email"`
| tokenURL | The endpoint is used by the client to obtain an access token by presenting its authorization grant or refresh token | `"https://accounts.google.com/o/oauth2/token"`
| headerName | The authorization header name to forward to your application | `"authorization"`
| endpointParamsQuery | Specifies additional parameters for requests to the token endpoint | `true`
| authStyle | Optionally specifies how the endpoint wants the client ID & client secret sent. See the table of possible values below | `0`
| pathFilter | Applies the middleware only to requests matching the given path pattern | `".*/users/.*"`

### Possible values for `authStyle`

| Value | Meaning |
|-------|---------|
| `1`   | Sends the "client_id" and "client_secret" in the POST body as application/x-www-form-urlencoded parameters. |
| `2`   | Sends the "client_id" and "client_secret" using HTTP Basic Authorization. This is an optional style described in the [OAuth2 RFC 6749 section 2.3.1](https://tools.ietf.org/html/rfc6749#section-2.3.1). |
| `0`   | Means to auto-detect which authentication style the provider wants by trying both ways and caching the successful way for the future. |

## Dapr configuration

To be applied, the middleware must be referenced in a [configuration]({{% ref configuration-concept.md %}}). See [middleware pipelines]({{% ref "middleware.md#customize-processing-pipeline"%}}).

```yaml
apiVersion: dapr.io/v1alpha1
kind: Configuration
metadata:
  name: appconfig
spec:
  httpPipeline:
    handlers:
    - name: oauth2clientcredentials
      type: middleware.http.oauth2clientcredentials
```

## Request path filtering

The `pathFilter` field allows you to apply OAuth2 client credentials authentication selectively based on request paths using regex patterns. This enables implementing the least privilege principle by configuring multiple OAuth2 middlewares with different scopes for different API endpoints, ensuring services only receive the minimum permissions necessary for their intended operations.

### Example: Separate User and Admin Access

```yaml
# Read-only user access middleware
apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: oauth2clientcredentials-users
spec:
  type: middleware.http.oauth2clientcredentials
  version: v1
  metadata:
  - name: clientId
    value: "<your client ID>"
  - name: clientSecret
    value: "<your client secret>"
  - name: scopes
    value: "user:read profile:read"
  - name: tokenURL
    value: "https://accounts.google.com/o/oauth2/token"
  - name: headerName
    value: "authorization"
  - name: pathFilter
    value: "^/api/users/.*"
---
# Full admin access middleware  
apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: oauth2clientcredentials-admin
spec:
  type: middleware.http.oauth2clientcredentials
  version: v1
  metadata:
  - name: clientId
    value: "<your client ID>"
  - name: clientSecret
    value: "<your client secret>"
  - name: scopes
    value: "admin:read admin:write user:read user:write"
  - name: tokenURL
    value: "https://accounts.google.com/o/oauth2/token"
  - name: headerName
    value: "authorization"
  - name: pathFilter
    value: "^/api/admin/.*"
```

In this configuration:

## Related links
- [Middleware]({{% ref middleware.md %}})
- [Configuration concept]({{% ref configuration-concept.md %}})
- [Configuration overview]({{% ref configuration-overview.md %}})