update OneLogin IdP doc (#2533)

* update OneLogin IdP doc

* include 3rd party warning

docs/docs/identity-providers/one-login.md

@@ -1,65 +1,113 @@
 # OneLogin
 
-Log in to your [OneLogin](https://www.onelogin.com/) account and head to the dashboard.
+This doc describes how to create an OIDC app in [OneLogin] for Pomerium and connect to it. It assumes you have already [installed Pomerium].
+
+::: warning
+While we do our best to keep our documentation up to date, changes to third-party systems are outside our control. Refer to [Connect an OIDC enabled app](https://developers.onelogin.com/openid-connect/connect-to-onelogin) from OneLogin's documentation as needed, or [let us know](https://github.com/pomerium/pomerium/issues/new?assignees=&labels=&template=bug_report.md) if we need to re-visit this page.
+:::
 
 ## Create OpenID Connect App
 
-Click **Apps** on the top menu. Select the **Add apps** menu item.
+1. Log in to your [OneLogin](https://www.onelogin.com/) account and click on **Administration** at the top.
+
+1. Navigate to **Applications** on the top menu. Click the **Add App** button:
+
+   ![One Login Add a New App](./img/onelogin/one-login-add-app.png)
+
+1. On the **Find Application** page, search for **openid**. Select **Openid Connect** by OneLogin, Inc.
+
+   ![One Login Add a New App](./img/onelogin/one-login-add-open-id.png)
+
+1. On the App Configuration page, name the app and select a logo:
+
+   ![One Login select logo](./img/onelogin/one-login-select-logo.png)
+
+   Select **Save**.
 
-![One Login Add a New App](./img/one-login-add-app.png)
+1. From the **Configuration** tab, set set the **Redirect URI's** to Pomerium's redirect url (`https://${authenticate_service_url}/oauth2/callback`):
 
-On the **Find Application** page, search for **openid**. Select **Openid Connect** by OneLogin, Inc.
+   ![One Login set callback url](./img/onelogin/one-login-callback-url.png)
 
-![One Login Add a New App](./img/one-login-add-open-id.png)
+   Select **Save**.
 
-On the App Configuration page, **name the app** and **select a logo**. Select **Save**.
+1. Navigate to the **SSO** page. This section contains the **[Client ID]**, **[Client Secret]** and **[Identity Provider URL]** you'll use to configure Pomerium:
 
-![One Login select logo](./img/one-login-select-logo.png)
+   ![One Login SSO settings](./img/onelogin/one-login-sso-settings.png)
 
-Next, set set the **Redirect URI's** setting to be Pomerium's redirect url `https://${authenticate_service_url}/oauth2/callback`.
+1. Set the application type to **Web** and the token endpoint to be **POST**.
 
-![One Login set callback url](./img/one-login-callback-url.png)
+1. Under **Token Timeout settings** set **Refresh Token** to 60 minutes (or whatever value makes sense for your organization). Note, however, if you don't enable refresh tokens the user will be prompted to authenticate whenever the access token expires which can result in a poor user experience.
 
-Go to the **SSO** page. This section contains the **[Client ID]** and **[Client Secret]** you'll use to configure Pomerium.
+   Select **Save** to complete the application configuration.
 
-Set the application type to **Web** and the token endpoint to be **POST**.
+### Add Users
 
-Under **Token Timeout settings** set **Refresh Token** to 60 minutes (or whatever value makes sense for your organization). Note, however, if you don't enable refresh tokens the user will be prompted to authenticate whenever the access token expires which can result in a poor user experience.
+OneLogin will not make your new application accessible to members of your organization automatically. You can assign access to individual users (as shown below), or define rules / policies based on group membership.
 
-![One Login SSO settings](./img/one-login-sso-settings.png)
+![One Login Application Access](./img/onelogin/one-login-app-access.png)
 
 ## Service Account
 
-To use `allowed_groups` in a policy an `idp_service_account` needs to be set in the Pomerium configuration. The service account for OneLogin uses a **different** client ID and client secret from the one configured above. It can be created with "Read users" access under Developers/API Credentials:
+To use `allowed_groups` in a policy, an `idp_service_account` needs to be set in the Pomerium configuration. The service account for OneLogin uses a *different* client ID and client secret from the one configured above.
 
-![API Access](./img/one-login-api-access.png)
+1. From the **Administration** dashboard, navigate to **Developers → API Credentials** and select **New Credential**.
 
+1. Name the new credential and rive it "Read users" access:
 
-The format of the `idp_service_account` for OneLogin is a base64-encoded JSON document:
+![API Access](./img/onelogin/one-login-api-access.png)
+
+
+1. The format of the `idp_service_account` for OneLogin is a base64-encoded JSON document:
+
+   ```json
+   {
+   "client_id": "...",
+   "client_secret": "..."
+   }
+   ```
+
+   You can save the object as a temporary file to encode:
+
+   ```bash
+   cat tmp.json | base64 -w 0
+   ```
 
-```json
-{
-  "client_id": "...",
-  "client_secret": "..."
-}
-```
 A [Group's ID](https://developers.onelogin.com/openid-connect/api/user-info) will be used to affirm user group membership.
 
 ## Pomerium Configuration
 
+Update your Pomerium configuration:
+
+:::: tabs
+::: tab config.yaml
+```yaml
+idp_provider: "onelogin"
+idp_provider_url: "https://awesomecompany.onelogin.com/oidc/2"
+idp_client_id: "REDACTED" # Your OneLogin application ID
+idp_client_secret: "REDACTED" # Your OneLogin application secret
+idp_service_account: "REDACTED" # API credentials, base64-encoded
+```
+:::
+::: tab Environment Variables
 ```bash
 IDP_PROVIDER="onelogin"
-IDP_PROVIDER_URL="https://openid-connect.onelogin.com/oidc"
-IDP_CLIENT_ID="9e613ce0-1622-0137-452d-0a93c31f8392142934"
-IDP_CLIENT_SECRET="3e86ef0cc21b6dcf10c1d91e032568617d37e9fe1609ffd8042d3c25a560c36c"
+IDP_PROVIDER_URL="https://awesomecompany.onelogin.com/oidc/2"
+IDP_CLIENT_ID="REDACTED" # Your OneLogin application ID
+IDP_CLIENT_SECRET="REDACTED" # Your OneLogin application secret
+IDP_SERVICE_ACCOUNT="REDACTED" # API credentials, base64-encoded
 ```
+:::
+::::
 
 After reloading Pomerium, you should be able to see any login events from your OneLogin events dashboard.
 
-![One Login Events Dashboard](./img/one-login-events.png)
+![One Login Events Dashboard](./img/onelogin/one-login-events.png)
 
-[client id]: ../../reference/readme.md#identity-provider-client-id
-[client secret]: ../../reference/readme.md#identity-provider-client-secret
+[client id]: /reference/readme.md#identity-provider-client-id
+[client secret]: /reference/readme.md#identity-provider-client-secret
+[Identity Provider URL]: /reference/readme.md#identity-provider-url
 [environmental variables]: https://en.wikipedia.org/wiki/Environment_variable
 [oauth2]: https://oauth.net/2/
 [openid connect]: https://en.wikipedia.org/wiki/OpenID_Connect
+[OneLogin]: https://www.onelogin.com/
+[installed Pomerium]: /docs/install/readme.md