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Vultr profile image Sanskriti Harmukh
Sanskriti Harmukh for Vultr

Posted on with Aashish Chaurasiya • Originally published at docs.vultr.com

Deploying Mattermost - An Open-Source Slack Alternative on Ubuntu 22.04

#selfhosted #devops #communication #security

Mattermost is an open-source, self-hosted team messaging platform that offers a secure, customizable alternative to Slack with channels, threads, file sharing, and integrations under your own control. This guide deploys the Mattermost Team Edition on Ubuntu 22.04 backed by a managed PostgreSQL database, fronts it with Nginx for HTTPS via Let's Encrypt, and wires Postfix for outbound email. By the end, you'll have Mattermost serving a team workspace securely at your domain.

Prerequisite: Ubuntu 22.04 server with 4 GB+ RAM, a PostgreSQL endpoint you can reach (managed or self-hosted), and a domain with an A record pointing at the server.

Create the Mattermost Database

1. Install the PostgreSQL client:

$ sudo apt install postgresql-client
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2. Connect to the PostgreSQL endpoint:

$ psql -h DB_HOST -U DB_ADMIN -p DB_PORT -d defaultdb
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3. Create the database, user, and grants:

CREATE DATABASE mattermostdb;
CREATE USER mmadmin WITH PASSWORD 'your-password';
GRANT ALL PRIVILEGES ON DATABASE mattermostdb TO mmadmin;
GRANT USAGE, CREATE ON SCHEMA PUBLIC TO mmadmin;
ALTER DATABASE mattermostdb OWNER TO mmadmin;
\q
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Install Mattermost from the Official APT Repository

1. Trust the Mattermost signing key:

$ curl -sL -o- https://deb.packages.mattermost.com/pubkey.gpg | gpg --dearmor | sudo tee /usr/share/keyrings/mattermost-archive-keyring.gpg > /dev/null
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2. Add the repository:

$ curl -o- https://deb.packages.mattermost.com/repo-setup.sh | sudo bash -s mattermost
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3. Install the server:

$ sudo apt update
$ sudo apt install mattermost -y
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Configure Mattermost

1. Edit the server configuration:

$ sudo nano /opt/mattermost/config/config.json
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Set:

"SiteURL": "https://mattermost.example.com"
"DataSource": "postgres://mmadmin:your-password@DB_HOST:DB_PORT/mattermostdb?sslmode=require&connect_timeout=10&binary_parameters=yes"
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2. Start and enable the service:

$ sudo systemctl enable --now mattermost
$ sudo systemctl status mattermost
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Front Mattermost with Nginx and Let's Encrypt

1. Open the HTTPS ports:

$ sudo ufw allow 80 comment 'mattermost http'
$ sudo ufw allow 443 comment 'mattermost https'
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2. Issue a Let's Encrypt certificate:

$ sudo apt install python3-certbot-nginx -y
$ sudo certbot --standalone certonly -d mattermost.example.com --agree-tos
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3. Create the Nginx virtual host:

$ sudo nano /etc/nginx/sites-available/mattermost.example.com
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upstream mattermost {
   server 127.0.0.1:8065;
   keepalive 32;
}

server {
  listen 80 default_server;
  server_name mattermost.example.com;
  return 301 https://$server_name$request_uri;
}

server {
   listen 443 ssl http2;
   listen [::]:443 ssl http2;
   server_name mattermost.example.com;

   ssl_certificate /etc/letsencrypt/live/mattermost.example.com/fullchain.pem;
   ssl_certificate_key /etc/letsencrypt/live/mattermost.example.com/privkey.pem;
   ssl_protocols TLSv1.2 TLSv1.3;

   location ~ /api/v[0-9]+/(users/)?websocket$ {
       proxy_pass http://mattermost;
       proxy_http_version 1.1;
       proxy_set_header Upgrade $http_upgrade;
       proxy_set_header Connection "upgrade";
   }

   location / {
       client_max_body_size 100M;
       proxy_pass http://mattermost;
   }
}
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4. Enable the site and reload Nginx:

$ sudo ln -s /etc/nginx/sites-available/mattermost.example.com /etc/nginx/sites-enabled/
$ sudo nginx -t
$ sudo systemctl restart nginx
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Configure Postfix for Outbound Email

1. Install Postfix and the mail CLI:

$ sudo apt install mailutils -y
$ sudo hostnamectl set-hostname mattermost.example.com
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2. Bind Postfix to localhost only:

$ sudo nano /etc/postfix/main.cf
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inet_interfaces = loopback-only
mydestination = localhost.$mydomain, localhost, $myhostname
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3. Restart Postfix and send a test:

$ sudo systemctl restart postfix
$ echo "Test message" | mail -s "Hello" admin@example.com
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Complete the Setup

  1. Open https://mattermost.example.com and create the first administrator account.
  2. Choose a team name and URL.
  3. Invite team members and create channels.
  4. (Optional) Connect S3-compatible object storage under Admin Console → File Storage for attachments, screenshots, and avatars.

Next Steps

Mattermost is running and served securely over HTTPS. From here you can:

  • Connect S3-compatible object storage for media attachments
  • Enable SAML, OIDC, or LDAP under Admin Console → Authentication
  • Install integrations (Jira, GitHub, PagerDuty, custom webhooks) from the marketplace

For the full guide with additional tips, visit the original article on Vultr Docs.

Top comments (1)

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aldo_cve profile image
Aldo •

I remember the early days of rolling out our own internal communication platforms, long before the current crop of SaaS offerings matured. There's a definite draw to having complete control over your data and infrastructure, especially with something like Mattermost where the customizability runs deep. Getting it running on Ubuntu is usually the easy part; the real challenge often starts after that initial deployment.

What often gets underestimated, though, is the ongoing operational overhead. Keeping Ubuntu and Mattermost itself patched, managing database backups, ensuring robust security configurations, and handling SSL certificate renewals quickly becomes a non-trivial part-time job, even for a relatively small instance. We've seen teams invest heavily in a "free" self-hosted solution, only to find the engineering hours spent on maintenance far exceeded what a managed service would have cost.

For teams with specific compliance needs or truly unique integration requirements that only self-hosting can address, the investment in dedicated ops time can be justified. But for many others, the "cost" of a paid Slack or Teams subscription often pales in comparison to the opportunity cost of pulling engineers away from core product development to maintain an internal chat server. It's a constant balancing act between control and focus, and it's always worth thoroughly calculating the total cost of ownership over several years.