# OIDC/SSO Automation

This document explains the fully automated OIDC/SSO setup between Zitadel and Nextcloud.

## Overview

The infrastructure now supports **fully automated** OIDC application provisioning, eliminating manual configuration steps. This makes the system scalable to dozens or hundreds of servers.

## How It Works

### 1. Automated OIDC App Creation

When deploying a new client, the Ansible playbook automatically:

1. **Authenticates with Zitadel** using admin credentials
2. **Creates OIDC application** via Zitadel Management API
3. **Retrieves client credentials** (client ID and secret)
4. **Configures Nextcloud** with the OIDC provider

### 2. Zero Manual Steps

The entire SSO setup happens automatically during deployment:

```bash
ansible-playbook -i hcloud.yml playbooks/deploy.yml
```

No need to:
- Login to Zitadel console
- Manually create OIDC apps
- Copy/paste client credentials
- Configure Nextcloud manually

### 3. Scalability

This automation makes it trivial to deploy **dozens of servers**:

```yaml
# terraform.tfvars
clients = {
  client1 = { ... }
  client2 = { ... }
  client3 = { ... }
  # Add as many as needed!
}
```

Each client gets:
- Its own Zitadel instance
- Its own Nextcloud instance
- Automatic OIDC configuration
- Unique credentials

## Technical Implementation

### Components

1. **`get_admin_token.sh`**: Authenticates with Zitadel using admin credentials
2. **`create_oidc_app.py`**: Creates OIDC app via Zitadel Management API
3. **`oidc-apps.yml`**: Ansible task orchestrating the automation
4. **`nextcloud/oidc.yml`**: Configures Nextcloud with OIDC provider

### Authentication Flow

```
1. Ansible → get_admin_token.sh → Zitadel OAuth2
2. Receives → JWT access token
3. Ansible → create_oidc_app.py → Zitadel Management API
4. Creates → OIDC application
5. Returns → Client ID + Client Secret
6. Ansible → Nextcloud occ command
7. Configures → OIDC provider
```

### API Endpoints Used

- **Token**: `POST https://{domain}/oauth/v2/token`
- **Projects**: `POST https://{domain}/management/v1/projects/_search`
- **Create App**: `POST https://{domain}/management/v1/projects/{id}/apps/oidc`

### Security Considerations

- Admin credentials are stored in **encrypted SOPS secrets**
- Access tokens are **ephemeral** (generated per-deployment)
- Client secrets are **never logged** (no_log: true)
- API calls use **HTTPS only**

## Configuration Options

### Zitadel OIDC App Settings

The automation creates apps with these settings:

```yaml
- Response Type: Authorization Code
- Grant Types: Authorization Code, Refresh Token
- App Type: Web Application
- Auth Method: Client Secret Basic
- Token Type: JWT
- Role Assertions: Enabled
- UserInfo Assertions: Enabled
```

### Nextcloud OIDC Provider

Configured with:

```yaml
- Provider Name: Zitadel
- Client ID: <auto-generated>
- Client Secret: <auto-generated>
- Discovery URI: https://{domain}/.well-known/openid-configuration
```

## Testing

After deployment, verify SSO works:

1. Visit: `https://nextcloud.{client}.vrije.cloud`
2. Click "Login with SSO" or "Zitadel"
3. Redirected to Zitadel login
4. Enter Zitadel credentials
5. Redirected back to Nextcloud (logged in)

## Troubleshooting

### OIDC App Not Created

Check Ansible output for errors in:
- `Get admin access token for API calls`
- `Create OIDC application for Nextcloud`

Common issues:
- Admin password incorrect
- Zitadel API not accessible
- Network connectivity issues

### Nextcloud OIDC Not Configured

Check if credentials were passed:
- `nextcloud_oidc_client_id` should be defined
- `nextcloud_oidc_client_secret` should be defined

Verify in Nextcloud:
```bash
docker exec -u www-data nextcloud php occ user_oidc:provider
```

### SSO Login Fails

Check redirect URI matches exactly:
```
https://nextcloud.{client}.vrije.cloud/apps/user_oidc/code
```

Check Zitadel application settings:
- Redirect URIs configured correctly
- Grant types include Authorization Code
- Application is active (not disabled)

## Future Enhancements

Potential improvements:

1. **Service Account**: Use dedicated service account instead of admin
2. **Token Caching**: Cache access tokens to reduce API calls
3. **Multi-App Support**: Automate Collabora, OnlyOffice, etc.
4. **Role Mapping**: Sync Zitadel roles to Nextcloud groups
5. **User Provisioning**: Auto-create users on first SSO login

## References

- [Zitadel Management API](https://zitadel.com/docs/apis/resources/mgmt)
- [Nextcloud OIDC App](https://github.com/nextcloud/user_oidc)
- [OAuth 2.0 Authorization Code Flow](https://oauth.net/2/grant-types/authorization-code/)