Mattermost

Mattermost is an open-source, self-hosted messaging and collaboration platform for teams. It provides channels, direct messages, file sharing, search, and integrations as a private alternative to hosted chat services, with your data staying on your own infrastructure. The server listens on port 8065.

Software included

Component	Version
Mattermost Team Edition	11.8.3
PostgreSQL	18 Alpine
Ubuntu	24.04 LTS

Environment variables

Set these optionally when you deploy from the marketplace. Leave a field blank to have a secure value generated.

Variable	Description
DOMAIN	Public domain for Mattermost
POSTGRES_PASSWORD	PostgreSQL password
MM_SERVICESETTINGS_SITEURL	Public site URL for Mattermost

Getting started

1. Connect to your VM

ssh ubuntu@<your-vm-ip>

2. Wait for first-boot configuration

On first boot, Mattermost generates a database password and starts PostgreSQL, Mattermost, and Nginx as a Docker Compose stack. Track progress with:

sudo journalctl -u mattermost-first-boot.service -f

Then verify the stack:

cd /opt/mattermost && docker compose ps

3. Access the Mattermost UI

If you set DOMAIN or MM_SERVICESETTINGS_SITEURL at deploy time, point a DNS record for that hostname at the VM and open it over HTTPS through a reverse proxy that terminates TLS:

https://<your-domain>

If you left those unset, reach the VM directly by IP:

http://<your-vm-ip>

Complete the setup wizard to create your administrator account. The first account you create becomes the System Administrator. The image does not create shared default login credentials.

Managing Mattermost

Mattermost runs as a Docker Compose stack in /opt/mattermost.

# Check status
cd /opt/mattermost && docker compose ps

# Restart
cd /opt/mattermost && docker compose restart

# View logs
cd /opt/mattermost && docker compose logs -f

Path	Purpose
/opt/mattermost/docker-compose.yml	Compose stack
/opt/mattermost/.env	Database and Mattermost environment
/opt/mattermost/volumes/db/	PostgreSQL data
/opt/mattermost/volumes/app/mattermost/	Mattermost config, files, logs, and data

Security

Mattermost is exposed through Nginx on port 80. The application port 8065 stays inside the Docker network. UFW is enabled and allows HTTP (port 80) and SSH (port 22).

To restrict the UI to a specific IP:

sudo ufw delete allow 80/tcp
sudo ufw allow from <trusted-ip> to any port 80

To access the UI without leaving port 80 open, use an SSH tunnel:

First close the public port on the VM, since it is open by default:

sudo ufw delete allow 80/tcp

# Run this on your local machine
ssh -L 8080:localhost:80 ubuntu@<your-vm-ip>

# Then open in a browser
http://localhost:8080

For production use, place Mattermost behind a reverse proxy with a trusted TLS certificate and set its site URL to your public HTTPS domain.

Caution

Create the first administrator promptly and restrict access to trusted users while you complete setup. The first account created receives System Administrator privileges.

Next steps

• Mattermost documentation
• Mattermost installation guide