add docs for generic oauth 2.0 connector

content/docs/connectors/_index.md

@@ -32,6 +32,7 @@ Dex implements the following connectors:
 | [OpenShift](/docs/connectors/openshift/) | no | yes | no | stable | |
 | [Atlassian Crowd](/docs/connectors/atlassian-crowd/) | yes | yes | yes * | beta | preferred_username claim must be configured through config |
 | [Gitea](/docs/connectors/gitea/) | yes | no | yes | alpha | |
+| [Generic OAuth 2.0](/docs/connectors/oauth/) | no | yes | yes | alpha |
 
 Stable, beta, and alpha are defined as:
 

content/docs/connectors/oauth.md

@@ -0,0 +1,74 @@
+---
+title: "Authentication Through an Generic OAuth 2.0 Provider"
+linkTitle: "Generic OAuth 2.0"
+description: ""
+date: 2021-03-15
+draft: false
+toc: true
+weight: 2050
+---
+
+## Overview
+
+Dex users can make use of this connector to work with standards-compliant [OAuth 2.0](https://oauth.net/2/) authorization providers, in case those authorization providers are not already in the Dex connectors list.
+
+## Configuration
+
+The following is an example of a configuration for using OAuth connector with Reddit.
+
+```yaml
+connectors:
+- type: oauth
+  # ID of OAuth 2.0 provider
+  id: reddit 
+  # Name of OAuth 2.0 provider
+  name: reddit
+  config:
+    # Connector config values starting with a "$" will read from the environment.
+    clientID: $REDDIT_CLIENT_ID
+    clientSecret: $REDDIT_CLIENT_SECRET
+    redirectURI: http://127.0.0.1:5556/callback
+
+    tokenURL: https://www.reddit.com/api/v1/access_token
+    authorizationURL: https://www.reddit.com/api/v1/authorize
+    userInfoURL: https: https://www.reddit.com/api/v1/me
+
+    # Optional: Specify whether to communicate to Auth provider without
+    # validating SSL certificates
+    # insecureSkipVerify: false
+
+    # Optional: The location of file containing SSL certificates to commmunicate
+    # to Auth provider
+    # rootCAs: /etc/ssl/reddit.pem
+
+    # Optional: List of scopes to request Auth provider for access user account
+    # scopes:
+    #  - identity
+
+    # Optional: Configurable keys for user ID look up
+    # Default: id
+    # userIDKey:
+
+    # Auth roviders return non-standard user identity profile
+    # Use claimMapping to map those user infomations to standard claims:
+    claimMapping:
+      # Optional: Configurable keys for user name look up
+      # Default: user_name
+      # userNameKey:
+
+      # Optional: Configurable keys for preferred username look up
+      # Default: preferred_username
+      # preferredUsernameKey:
+
+      # Optional: Configurable keys for user groups look up
+      # Default: groups
+      # groupsKey:
+
+      # Optional: Configurable keys for email look up
+      # Default: email
+      # emailKey:
+
+      # Optional: Configurable keys for email verified look up
+      # Default: email_verified
+      # emailVerifiedKey:
+```