> ## Documentation Index
> Fetch the complete documentation index at: https://docs.opus-host.de/llms.txt
> Use this file to discover all available pages before exploring further.

# Install MySQL or PostgreSQL on Your Opus Host VPS

> Install and secure MySQL or PostgreSQL on your Opus Host VPS, create databases and users, and connect from your applications.

Most apps need a database. This guide covers installing and securing MySQL and PostgreSQL, the two most common options, on your Opus Host VPS.

<Tabs>
  <Tab title="MySQL">
    ## Install MySQL

    ```bash theme={null}
    sudo apt update
    sudo apt install -y mysql-server
    ```

    ## Secure the installation

    ```bash theme={null}
    sudo mysql_secure_installation
    ```

    Answer **Y** to remove anonymous users, disallow remote root login, remove the test database, and reload privileges.

    ## Create a database and user

    ```bash theme={null}
    sudo mysql
    ```

    ```sql theme={null}
    CREATE DATABASE myapp;
    CREATE USER 'myuser'@'localhost' IDENTIFIED BY 'change-this-password';
    GRANT ALL PRIVILEGES ON myapp.* TO 'myuser'@'localhost';
    FLUSH PRIVILEGES;
    EXIT;
    ```

    ## Connect from the command line

    ```bash theme={null}
    mysql -u myuser -p myapp
    ```
  </Tab>

  <Tab title="PostgreSQL">
    ## Install PostgreSQL

    ```bash theme={null}
    sudo apt update
    sudo apt install -y postgresql postgresql-contrib
    ```

    ## Create a database and user

    Switch to the `postgres` system user and open the psql shell:

    ```bash theme={null}
    sudo -u postgres psql
    ```

    ```sql theme={null}
    CREATE DATABASE myapp;
    CREATE USER myuser WITH ENCRYPTED PASSWORD 'change-this-password';
    GRANT ALL PRIVILEGES ON DATABASE myapp TO myuser;
    \q
    ```

    ## Connect from the command line

    ```bash theme={null}
    psql -h localhost -U myuser -d myapp
    ```
  </Tab>
</Tabs>

## Allow remote connections (optional)

By default both databases only accept connections from `localhost`, which is the safest setup. If your app runs on the same VPS, leave it that way. If you truly need remote access:

1. Bind the database to `0.0.0.0` in its config (`/etc/mysql/mysql.conf.d/mysqld.cnf` or `/etc/postgresql/*/main/postgresql.conf`).
2. Update the client authentication file (`pg_hba.conf` for PostgreSQL).
3. Open the port in your firewall. See [Firewall](/vps/firewall).
4. Restart the service.

<Warning>
  Never expose a database to the public internet without a strong password, a firewall rule limiting source IPs, and TLS. Databases are constantly scanned and brute-forced.
</Warning>

## Back up a database

```bash theme={null}
# MySQL
mysqldump -u myuser -p myapp > myapp-backup.sql

# PostgreSQL
pg_dump -U myuser myapp > myapp-backup.sql
```

Automate this with a [cron job](/vps/cron-jobs).