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Run the Mattermost Access Request plugin

This guide explains how to integrate Teleport access requests with Mattermost, an open source messaging platform. The Teleport Mattermost plugin notifies individuals of access requests. Users can then approve and deny access requests by following the message link, making it easier to implement security best practices without compromising productivity.

The Mattermost Access Request plugin

This integration is hosted on Teleport Cloud

In Teleport Enterprise Cloud, Teleport manages the Mattermost integration for you, and you can enroll the Mattermost integration from the Teleport Web UI.

Visit the Teleport Web UI and click Access Management on the menu bar at the top of the screen.

On the left sidebar, click Enroll New Integration to visit the "Enroll New Integration" page:

Enroll an Access Request plugin

On the "Select Integration Type" menu, click the tile for your integration. You will see a page with instructions to set up the integration, as well as a form that you can use to configure the integration.

Prerequisites​

Recommended: Configure Machine ID to provide short-lived Teleport credentials to the plugin. Before following this guide, follow a Machine ID deployment guide to run the tbot binary on your infrastructure.

  • A Mattermost account with admin privileges. This plugin has been tested with Mattermost v7.0.1.
  • Either a Linux host or Kubernetes cluster where you will run the Teleport Mattermost plugin.
  • To check that you can connect to your Teleport cluster, sign in with tsh login, then verify that you can run tctl commands using your current credentials. tctl is supported on macOS and Linux machines. For example: 
    $ tsh login --proxy=teleport.example.com --user=email@example.com
    $ tctl status
    # Cluster  teleport.example.com
    # Version  15.4.22
    # CA pin   sha256:abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678
    If you can connect to the cluster and run the tctl status command, you can use your current credentials to run subsequent tctl commands from your workstation. If you host your own Teleport cluster, you can also run tctl commands on the computer that hosts the Teleport Auth Service for full permissions.

Step 1/8. Define RBAC resources​

Before you set up the Teleport Mattermost plugin, you need to enable Role Access Requests in the Teleport Proxy Service or Teleport Auth Service.

For the purpose of this guide, we will define an editor-requester role, which can request the built-in editor role, and an editor-reviewer role that can review requests for the editor role.

Create a file called editor-request-rbac.yaml with the following content:

kind: role
version: v5
metadata:
  name: editor-reviewer
spec:
  allow:
    review_requests:
      roles: ['editor']
---
kind: role
version: v5
metadata:
  name: editor-requester
spec:
  allow:
    request:
      roles: ['editor']
      thresholds:
        - approve: 1
          deny: 1

Create the roles you defined:

$ tctl create -f editor-request-rbac.yaml
role 'editor-reviewer' has been created
role 'editor-requester' has been created

Allow yourself to review requests by users with the editor-requester role by assigning yourself the editor-reviewer role.

Assign the editor-reviewer role to your Teleport user by running the appropriate commands for your authentication provider:

  1. Retrieve your local user's roles as a comma-separated list:

    $ ROLES=$(tsh status -f json | jq -r '.active.roles | join(",")')

  2. Edit your local user to add the new role:

    $ tctl users update $(tsh status -f json | jq -r '.active.username') \
      --set-roles "${ROLES?},editor-reviewer"

  3. Sign out of the Teleport cluster and sign in again to assume the new role.

Create a user called myuser who has the editor-requester role. This user cannot edit your cluster configuration unless they request the editor role:

$ tctl users add myuser --roles=editor-requester

tctl will print an invitation URL to your terminal. Visit the URL and log in as myuser for the first time, registering credentials as configured for your Teleport cluster.

Later in this guide, you will have myuser request the editor role so you can review the request using the Teleport plugin.

Step 2/8. Install the Teleport Mattermost plugin​

We recommend installing Teleport plugins on the same host as the Teleport Proxy Service. This is an ideal location as plugins have a low memory footprint, and require both public internet access and Teleport Auth Service access.

We currently only provide linux-amd64 binaries. You can also compile these plugins from source. You can run the plugin from a remote host or your local development machine.

$ curl -L -O https://get.gravitational.com/teleport-access-mattermost-v15.4.22-linux-amd64-bin.tar.gz
$ tar -xzf teleport-access-mattermost-v15.4.22-linux-amd64-bin.tar.gz
$ cd teleport-access-mattermost
$ sudo ./install

Make sure the binary is installed:

$ teleport-mattermost version
teleport-mattermost v15.4.22 git:teleport-mattermost-v15.4.22-fffffffff go1.21

Step 3/8. Create a user and role for the plugin​

Teleport's Access Request plugins authenticate to your Teleport cluster as a user with permissions to list and read Access Requests. This way, plugins can retrieve Access Requests from the Teleport Auth Service and present them to reviewers.

Define a user and role called access-plugin by adding the following content to a file called access-plugin.yaml:

kind: role
version: v5
metadata:
  name: access-plugin
spec:
  allow:
    rules:
      - resources: ['access_request']
        verbs: ['list', 'read']
      - resources: ['access_plugin_data']
        verbs: ['update']
---
kind: user
metadata:
  name: access-plugin
spec:
  roles: ['access-plugin']
version: v2

Create the user and role:

$ tctl create -f access-plugin.yaml

As with all Teleport users, the Teleport Auth Service authenticates the access-plugin user by issuing short-lived TLS credentials. In this case, we will need to request the credentials manually by impersonating the access-plugin role and user.

If you are running a self-hosted Teleport Enterprise deployment and are using tctl from the Auth Service host, you will already have impersonation privileges.

To grant your user impersonation privileges for access-plugin, define a role called access-plugin-impersonator by pasting the following YAML document into a file called access-plugin-impersonator.yaml:

kind: role
version: v5
metadata:
  name: access-plugin-impersonator
spec:
  allow:
    impersonate:
      roles:
      - access-plugin
      users:
      - access-plugin

Create the access-plugin-impersonator role:

$ tctl create -f access-plugin-impersonator.yaml

If you are providing identity files to the plugin with Machine ID, assign the access-plugin role to the Machine ID bot user. Otherwise, assign this role to the user you plan to use to generate credentials for the access-plugin role and user:

Assign the access-plugin-impersonator role to your Teleport user by running the appropriate commands for your authentication provider:

  1. Retrieve your local user's roles as a comma-separated list:

    $ ROLES=$(tsh status -f json | jq -r '.active.roles | join(",")')

  2. Edit your local user to add the new role:

    $ tctl users update $(tsh status -f json | jq -r '.active.username') \
      --set-roles "${ROLES?},access-plugin-impersonator"

  3. Sign out of the Teleport cluster and sign in again to assume the new role.

You will now be able to generate signed certificates for the access-plugin role and user.

Step 4/8. Export the access plugin identity​

Give the plugin access to a Teleport identity file. We recommend using Machine ID for this in order to produce short-lived identity files that are less dangerous if exfiltrated, though in demo deployments, you can generate longer-lived identity files with tctl:

Configure tbot with an output that will produce the credentials needed by the plugin. As the plugin will be accessing the Teleport API, the correct output type to use is identity.

For this guide, the directory destination will be used. This will write these credentials to a specified directory on disk. Ensure that this directory can be written to by the Linux user that tbot runs as, and that it can be read by the Linux user that the plugin will run as.

Modify your tbot configuration to add an identity output.

If running tbot on a Linux server, use the directory output to write identity files to the /opt/machine-id directory:

outputs:
- type: identity
  destination:
    type: directory
    # For this guide, /opt/machine-id is used as the destination directory.
    # You may wish to customize this. Multiple outputs cannot share the same
    # destination.
    path: /opt/machine-id

If running tbot on Kubernetes, write the identity file to Kubernetes secret instead:

outputs:
  - type: identity
    destination:
      type: kubernetes_secret
      name: teleport-plugin-mattermost-identity

If operating tbot as a background service, restart it. If running tbot in one-shot mode, execute it now.

You should now see an identity file under /opt/machine-id or a Kubernetes secret named teleport-plugin-mattermost-identity. This contains the private key and signed certificates needed by the plugin to authenticate with the Teleport Auth Service.

Step 5/8. Register a Mattermost bot​

Now that you have generated the credentials your plugin needs to connect to your Teleport cluster, register your plugin with Mattermost so it can send Access Request messages to your workspace.

In Mattermost, click the menu button in the upper left of the UI, then click System Console → Integrations → Bot Accounts.

Set "Enable Bot Account Creation" to "true".

Enable Mattermost bots

This will allow you to create a new bot account for the Mattermost plugin.

Go back to your team. In the menu on the upper left of the UI, click Integrations → Bot Accounts → Add Bot Account.

Set the "Username", "Display Name", and "Description" fields according to how you would like the Mattermost plugin bot to appear in your workspace. Set "Role" to "Member".

You can download our avatar to set as your Bot Icon.

Set "post:all" to "Enabled".

Enable Mattermost Bots

Click "Create Bot Account". We will use the resulting OAuth 2.0 token when we configure the Mattermost plugin.

Step 6/8. Configure the Mattermost plugin​

At this point, you have generated credentials that the Mattermost plugin will use to connect to Teleport and Mattermost. You will now configure the Mattermost plugin to use these credentials and post messages in the right channels for your workspace.

The Mattermost plugin uses a configuration file in TOML format. On the host where you will run the Mattermost plugin, generate a boilerplate configuration by running the following commands:

$ teleport-mattermost configure > teleport-mattermost.toml
$ sudo mv teleport-mattermost.toml /etc

Edit the configuration as explained below:

[teleport]​

addr: Include the hostname and HTTPS port of your Teleport Proxy Service or Teleport Enterprise Cloud account (e.g., teleport.example.com:443 or mytenant.teleport.sh:443).

identity: Fill this in with the path to the identity file you exported earlier.

client_key, client_crt, root_cas: Comment these out, since we are not using them in this configuration.

If you are providing credentials to the plugin using a tbot binary that runs on a Linux server, make sure the value of identity is the same as the path of the identity file you configured tbot to generate, /opt/machine-id/identity.

Configure the plugin to periodically reload the identity file, ensuring that it does not attempt to connect to the Teleport Auth Service with expired credentials.

Add the following to the teleport section of the configuration:

refresh_identity = true

[mattermost]​

url: Include the scheme (https://) and fully qualified domain name of your Mattermost deployment.

token: Find your Mattermost bot's OAuth 2.0 token. To do so, visit Mattermost. In the menu on the upper left of the UI, go to Integrations → Bot Accounts. Find the listing for the Teleport plugin and click "Create New Token". After you save the token, you will see a message with text in the format, "Access Token: TOKEN". Copy the token and paste it here.

recipients: This field configures the channels that the Mattermost plugin will notify when it receives an Access Request message. The value is an array of strings, where each element is either:

  • The email address of a Mattermost user to notify via a direct message when the plugin receives an Access Request event
  • A channel name in the format team/channel, where / separates the name of the team and the name of the channel

For example, this configuration will notify first.last@example.com and the Town Square channel in the myteam team of any Access Request events:

recipients = [
  "myteam/Town Square",
  "first.last@example.com"
]

You will need to invite your Teleport plugin to any channel you add to the recipients list (aside from direct message channels). Visit Mattermost, navigate to each channel you want to invite the plugin to, and enter /invite @teleport (or the name of the bot you configured) into the message box.

Invite the bot

Suggested reviewers

Users can also suggest reviewers when they create an Access Request, e.g.,:

$ tsh request create --roles=dbadmin --reviewers=alice@example.com,ivan@example.com

If an Access Request includes suggested reviewers, the Mattermost plugin will add these to the list of channels to notify. If a suggested reviewer is an email address, the plugin will look up the the direct message channel for that address and post a message in that channel.

If recipients is empty, and the user requesting elevated privileges has not suggested any reviewers, the plugin will skip forwarding the Access Request to Mattermost.

The final configuration should look similar to this:

# example mattermost configuration TOML file
[teleport]
auth_server = "myinstance.teleport.sh:443"                   # Teleport Cloud proxy HTTPS address
identity = "/var/lib/teleport/plugins/mattermost/identity"   # Identity file path
refresh_identity = true                                      # Refresh identity file on a periodic basis

[mattermost]
url = "https://mattermost.example.com" # Mattermost Server URL
token = "api-token"                    # Mattermost Bot OAuth token
recipients = [
  "myteam/general",
  "first.last@example.com"
]

[log]
output = "stderr" # Logger output. Could be "stdout", "stderr" or "/var/lib/teleport/mattermost.log"
severity = "INFO" # Logger severity. Could be "INFO", "ERROR", "DEBUG" or "WARN".

Step 7/8. Test your Mattermost bot​

After modifying your configuration, run the bot with the following command:

$ teleport-mattermost start -d

The -d flag provides debug information to make sure the bot can connect to Mattermost, e.g.:

DEBU   Checking Teleport server version mattermost/main.go:234
DEBU   Starting a request watcher... mattermost/main.go:296
DEBU   Starting Mattermost API health check... mattermost/main.go:186
DEBU   Starting secure HTTPS server on :8081 utils/http.go:146
DEBU   Watcher connected mattermost/main.go:260
DEBU   Mattermost API health check finished ok mattermost/main.go:19

Create an Access Request​

A Teleport admin can create an Access Request for another user with tctl:

$ tctl request create myuser --roles=editor

The users and channels you configured earlier to review the request should receive a message from "Teleport" in Mattermost allowing them to visit a link in the Teleport Web UI and either approve or deny the request.

Resolve the request​

Once you receive an Access Request message, click the link to visit Teleport and approve or deny the request:

Reviewing a request

Reviewing from the command line

You can also review an Access Request from the command line:

# Replace REQUEST_ID with the id of the request
$ tctl request approve REQUEST_ID
$ tctl request deny REQUEST_ID
Auditing Access Requests

When the Mattermost plugin posts an Access Request notification to a channel, anyone with access to the channel can view the notification and follow the link. While users must be authorized via their Teleport roles to review Access Requests, you should still check the Teleport audit log to ensure that the right users are reviewing the right requests.

When auditing Access Request reviews, check for events with the type Access Request Reviewed in the Teleport Web UI.

Step 8/8. Set up systemd​

This section is only relevant if you are running the Teleport Mattermost plugin on a Linux host.

In production, we recommend starting the Teleport plugin daemon via an init system like systemd. Here's the recommended Teleport plugin service unit file for systemd:

(!examples/systemd/plugins/teleport-mattermost.service!)

Save this as teleport-mattermost.service in either /usr/lib/systemd/system/ or another unit file load path supported by systemd.

Enable and start the plugin:

$ sudo systemctl enable teleport-mattermost
$ sudo systemctl start teleport-mattermost