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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.

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