In order to enable Portainer, the docker-compose.yml and site.conf for Nginx must be modified.

1\. Create a new file `docker-compose.override.yml` in the mailcow-dockerized root folder and insert the following configuration
```yaml
version: '2.1'
services:
    portainer-mailcow:
      image: portainer/portainer-ce
      volumes:
        - /var/run/docker.sock:/var/run/docker.sock
        - ./data/conf/portainer:/data
      restart: always
      dns:
        - 172.22.1.254
      dns_search: mailcow-network
      networks:
        mailcow-network:
          aliases:
            - portainer
```
2a\. Create `data/conf/nginx/portainer.conf`:
```
upstream portainer {
  server portainer-mailcow:9000;
}

map $http_upgrade $connection_upgrade {
  default upgrade;
  '' close;
}
```

2b\. Insert a new location to the default mailcow site by creating the file `data/conf/nginx/site.portainer.custom`:
```
  location /portainer/ {
    proxy_http_version 1.1;
    proxy_set_header Host              $http_host;   # required for docker client's sake
    proxy_set_header X-Real-IP         $remote_addr; # pass on real client's IP
    proxy_set_header X-Forwarded-For   $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
    proxy_read_timeout                 900;

    proxy_set_header Connection "";
    proxy_buffers 32 4k;
    proxy_pass http://portainer/;
  }

  location /portainer/api/websocket/ {
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection $connection_upgrade;
    proxy_pass http://portainer/api/websocket/;
  }
```

3\. Apply your changes:
=== "docker compose (Plugin)"

    ``` bash
    docker compose up -d && docker compose restart nginx-mailcow
    ```

=== "docker-compose (Standalone)"

    ``` bash
    docker-compose up -d && docker-compose restart nginx-mailcow
    ```

Now you can simply navigate to https://${MAILCOW_HOSTNAME}/portainer/ to view your Portainer container monitoring page. You’ll then be prompted to specify a new password for the **admin** account. After specifying your password, you’ll then be able to connect to the Portainer UI.

---

## Reverse Proxy

If you are using a reverse proxy you will have to configure it to properly forward websocket requests.

This needs to be done for the docker console and other components to work.

Here is an example for Apache:

```
<Location /portainer/api/websocket/>
  RewriteEngine on
  RewriteCond %{HTTP:UPGRADE} ^WebSocket$ [NC]
  RewriteCond %{HTTP:CONNECTION} Upgrade$ [NC]
  RewriteRule /portainer/api/websocket/(.*) ws://127.0.0.1:8080/portainer/api/websocket/$1 [P]
</Location>
```