# Setting up Matrix User Verification Service (optional)

**[Matrix User Verification Service](https://github.com/matrix-org/matrix-user-verification-service) (hereafter: UVS) can only be installed after Matrix services are installed and running.** If you're just installing Matrix services for the first time, please continue with the [Configuration](configuring-playbook.md) / [Installation](installing.md) flow and come back here later.

Currently, the main purpose of this role is to allow Jitsi to authenticate Matrix users and check if they are authorized to join a conference. Please refer to the documentation of the [Matrix User Verification Service](https://github.com/matrix-org/matrix-user-verification-service) to understand how it works.

**Note**: enabling Matrix User Verification Service, means that the `openid` API endpoints will be exposed on the Matrix Federation port (usually `8448`), even if [federation](configuring-playbook-federation.md) is disabled.

If the Jitsi server is also configured by this playbook, all plugging of variables and secrets is handled in `group_vars/matrix_servers`.

__Some general concepts of UVS may be helpful to understand the rest, so here they are:__

UVS can be used to verify two claims:

* (A) Whether a given OpenID token is valid for a given server and
* (B) whether a user is member of a given room and the corresponding PowerLevel

Verifying an OpenID token ID done by finding the corresponding Homeserver via  '.well-known/matrix/server' for the given domain. The configured `matrix_user_verification_service_uvs_homeserver_url` does **not** factor into this. By default, this playbook only checks against `matrix_server_fqn_matrix`. Therefore, the request will be made against the public openid API for `matrix_server_fqn_matrix`.

Verifying RoomMembership and PowerLevel is done against `matrix_user_verification_service_uvs_homeserver_url` which is by default done via the docker network. UVS will verify the validity of the token beforehand though.

## Prerequisites

In order to use UVS, an admin token for the configured homeserver must be supplied. For now this means configuring Synapse and creating the token before installing UVS.

## Enable

To enable Matrix User Verification Service, add the following configuration to your `inventory/host_vars/matrix.example.com/vars.yml` file:

```yaml
matrix_user_verification_service_enabled: true
```

## Configuration

The only required configuration variable is `matrix_user_verification_service_uvs_access_token` (see below).

For a list of all configuration options see the role defaults [`roles/matrix-user-verification-service/defaults/main.yml`](../roles/custom/matrix-user-verification-service/defaults/main.yml). But be aware of all the plugging happening in `group_vars/matrix_servers`.

In the default configuration, the UVS Server is only reachable via the docker network, which is fine if e.g. Jitsi is also running in a container on the host. However, it is possible to expose UVS via setting `matrix_user_verification_service_container_http_host_bind_port`.

### Obtain an access token

The Synapse Access Token is used to verify RoomMembership and PowerLevel against `matrix_user_verification_service_uvs_homeserver_url`.

We recommend that you create a dedicated Matrix user for uvs (`uvs` is a good username). Follow our [Registering users](registering-users.md) guide to register a user with administration privileges.

You are required to specify an access token (belonging to this new user) for UVS to work. Refer to the documentation on [how to obtain an access token](obtaining-access-tokens.md).

⚠️ **Warning**: Access tokens are sensitive information. Do not include them in any bug reports, messages, or logs. Do not share the access token with anyone.

```yaml
matrix_user_verification_service_uvs_access_token: "YOUR ACCESS TOKEN HERE"
```

### Custom Auth Token (optional)

It is possible to set an API Auth Token to restrict access to the UVS. If this is enabled, anyone making a request to UVS must provide it via the header "Authorization: Bearer TOKEN"

By default, the token will be derived from `matrix_homeserver_generic_secret_key` in `group_vars/matrix_servers`.

To set your own Token, add the following configuration to your `vars.yml` file:

```yaml
matrix_user_verification_service_uvs_auth_token: "TOKEN"
```

In case Jitsi is also managed by this playbook and 'matrix' authentication in Jitsi is enabled, this collection will automatically configure Jitsi to use the configured auth token.

### Disable Auth (optional)

Authorization is enabled by default. To disable it, add the following configuration to your `vars.yml` file:

```yaml
matrix_user_verification_service_uvs_require_auth: false
```

### Federation (optional)

In theory (however currently untested), UVS can handle federation. To enable it, add the following configuration to your `vars.yml` file:

```yaml
matrix_user_verification_service_uvs_pin_openid_verify_server_name: false
```

This will instruct UVS to verify the OpenID token against any domain given in a request. Homeserver discovery is done via '.well-known/matrix/server' of the given domain.

## Installing

After configuring the playbook, run it with [playbook tags](playbook-tags.md) as below:

<!-- NOTE: let this conservative command run (instead of install-all) to make it clear that failure of the command means something is clearly broken. -->
```sh
ansible-playbook -i inventory/hosts setup.yml --tags=setup-all,start
```

The shortcut commands with the [`just` program](just.md) are also available: `just install-service matrix-user-verification-service` or `just setup-all`

`just install-service matrix-user-verification-service` is useful for maintaining your setup quickly when its components remain unchanged. If you adjust your `vars.yml` to remove other components, you'd need to run `just setup-all`, or these components will still remain installed. Note `just setup-all` runs the `ensure-matrix-users-created` tag too.

## Logging

The configuration variable `UVS_LOG_LEVEL` can be set to:
- warning
- info
- debug

## TLS Certificate Checking

If the Matrix Homeserver does not provide a valid TLS certificate, UVS will fail with the following error message:

> message: 'No response received: [object Object]',

This also applies to self-signed and let's encrypt staging certificates.

To disable certificate validation altogether (INSECURE! Not suitable for production use!) set: `NODE_TLS_REJECT_UNAUTHORIZED=0`

Alternatively, it is possible to inject your own CA certificates into the container by mounting a PEM file with additional trusted CAs into the container and pointing the `NODE_EXTRA_CA_CERTS` environment variable to it.