PG-2238 - Add the OIDC topic (#930)

This PR reorganizes the authentication methods in Solutions, adding a folder to future proof the authentication methods, and adds the OIDC topic.

Author: Andriciuc

docs/solutions.md

@@ -30,11 +30,11 @@ Dealing with spatial data? Learn how you can store and manipulate it.
 
 </div><div data-banner markdown>
 
-### :material-account-lock: LDAP authentication
+### :material-account-lock: Authentication
 
-Need a central authentication solution? Learn how you can manage users and access control using LDAP directories.
+Need centralized authentication? Learn how to integrate PostgreSQL with identity providers such as LDAP directories or OpenID Connect.
 
-[LDAP authentication :material-arrow-right:](ldap.md){.md-button}
+[Authentication :material-arrow-right:](solutions/authentication/overview.md){.md-button}
 
 </div>
 </div>

docs/ldap.md docs/solutions/authentication/ldap.mddocs/ldap.md renamed to docs/solutions/authentication/ldap.md

@@ -0,0 +1,79 @@
+# OIDC authentication
+
+[OpenID Connect :octicons-link-external-16:](https://openid.net/developers/how-connect-works/) (or OIDC) authentication allows you to authenticate using tokens issued by an external identity provider. Instead of managing database passwords, you can delegate authentication to centralized identity services.
+
+Percona Distribution for PostgreSQL integrates OIDC authentication using the `pg_oidc_validator` library, which validates OIDC tokens during client authentication.
+
+The library is compatible with any identity provider that implements the OIDC standard.
+
+For configuration details and source code, see the [pg_oidc_validator project :octicons-link-external-16:](https://github.com/Percona-Lab/pg_oidc_validator).
+
+!!! important
+    OIDC authentication relies on [PostgreSQL OAuth authentication :octicons-link-external-16:](https://www.postgresql.org/docs/current/auth-oauth.html), introduced in PostgreSQL 18.
+
+## When to use OIDC authentication
+
+OIDC authentication is useful when you want to:
+
+* integrate PostgreSQL with an existing single sign-on (SSO) platform
+* reduce the need to manage database passwords
+* centralize identity management across applications and databases
+
+!!! tip
+    OIDC authentication simplifies access management for PostgreSQL when using an identity provider that supports OpenID Connect.
+
+## OIDC authentication architecture
+
+OIDC authentication works as follows:
+
+1. The client obtains an access token from an external identity provider
+2. The client connects to PostgreSQL using OAuth authentication
+3. PostgreSQL forwards the token to the `pg_oidc_validator` module
+4. The validator verifies the token signature and claims
+5. If validation succeeds, PostgreSQL allows the connection
+
+The following diagram shows how OIDC authentication works between the client, the identity provider, and PostgreSQL:
+
+--8<-- "diagrams/oidc/auth-flow.md"
+
+!!! tip
+    Before configuring OIDC authentication, ensure that your PostgreSQL deployment can access the identity provider that issues OIDC tokens.
+
+## Set up OIDC authentication
+
+Follow these steps to set up OIDC authentication for your PostgreSQL database.
+{.power-number}
+
+1. Install the `pg_oidc_validator` package.
+
+    For more information, see the [Quickstart guide](../../installing.md).
+
+    Alternatively, you can build the extension from source:
+
+    ```bash
+    make USE_PGXS=1 install -j
+    ```
+
+    !!! note
+        A C++23 compiler and standard library is required to build `pg_oidc_validator`.
+
+2. Edit `postgresql.conf` and add the validator library:
+
+    ```ini
+    oauth_validator_libraries = 'pg_oidc_validator'
+    ```
+
+    !!! note
+        This setting tells PostgreSQL to load the OIDC validator during startup.
+
+3. Add an OAuth authentication rule to `pg_hba.conf`:
+
+    ```ini
+    host all all 192.168.1.0/24 oauth scope="pgadmin-a",issuer=https://oidc.example.com
+    ```
+
+    Where:
+
+    * `oauth` enables OAuth authentication
+    * `scope` is the required OIDC scope
+    * `issuer` is the URL of the OIDC identity provider

docs/solutions/authentication/oidc.md

@@ -0,0 +1,19 @@
+# Authentication
+
+Centralized authentication allows you to manage database access using external identity systems instead of local PostgreSQL users.
+
+Percona Distribution for PostgreSQL supports multiple authentication mechanisms that integrate with enterprise identity infrastructure.
+
+## Available authentication methods
+
+### OIDC authentication
+
+Authenticate users using OpenID Connect identity providers.
+
+[OIDC authentication :material-arrow-right:](oidc.md){.md-button}
+
+### LDAP authentication
+
+Use LDAP directories such as OpenLDAP or Active Directory to centrally manage database users.
+
+[LDAP authentication :material-arrow-right:](ldap.md){.md-button}

docs/solutions/authentication/overview.md

@@ -63,8 +63,10 @@ nav:
         - Deployment: solutions/postgis-deploy.md
         - Query spatial data: solutions/postgis-testing.md
         - Upgrade spatial database: solutions/postgis-upgrade.md
-      - LDAP authentication:
-          - ldap.md
+      - Authentication:
+        - Overview: solutions/authentication/overview.md
+        - OIDC authentication: solutions/authentication/oidc.md
+        - LDAP authentication: solutions/authentication/ldap.md
   - Upgrade:
       - "Major upgrade": major-upgrade.md
       - minor-upgrade.md

mkdocs.yml

@@ -0,0 +1,16 @@
+```mermaid
+sequenceDiagram
+    participant Client
+    participant IdP as Identity Provider (OIDC)
+    participant PostgreSQL
+    participant Validator as pg_oidc_validator
+
+    Client->>IdP: Request authentication
+    IdP-->>Client: Return OIDC access token
+
+    Client->>PostgreSQL: Connect using OAuth token
+    PostgreSQL->>Validator: Validate token
+    Validator-->>PostgreSQL: Token valid / invalid
+
+    PostgreSQL-->>Client: Connection allowed or rejected
+```