Using sockets for database

Mattermost requires a database back-end. If you plan to run it on the machine, install MySQL or PostgreSQL as the database. In this document let’s understand how you can use sockets for setting up the database.

MySQL

$ mysql -u root -p
CREATE DATABASE mattermostdb;
CREATE USER mmuser IDENTIFIED BY 'mmuser_password';
GRANT ALL ON mattermostdb.* TO mmuser;

PostgreSQL

Install and configure PostgreSQL.
Choose between TCP or UNIX Socket, and jump to the corresponding section.

With TCP socket

Create the new user while connecting to the server as postgres user (you will be prompted for a password for the new user):

sudo -u postgres createuser -P mmuser
Create the Mattermost database, owned by mmuser user:

sudo -u postgres createdb -O mmuser mattermostdb
In the connections and authentications section, set the listen_address list line per your needs:
/var/lib/postgres/data/postgresql.conf listen_address = 'localhost,my_local_ip_address'
You can use ‘*’ to listen on all available addresses.

Then add a line like the following to the authentication config:

/var/lib/postgres/data/pg_hba.conf
# TYPE  DATABASE        USER            ADDRESS                 METHOD
# IPv4 local connections:
host    all             all             ip_address/32   md5

Run the setup using:

$ psql --host=ip_address --dbname=mattermostdb --username=mmuser --password

With Unix socket

Create the new user while connecting to the server as postgres user:
```
sudo -u postgres createuser mattermost
```
Create the Mattermost database, owned by mattermost user:
```
sudo -u postgres createdb -O mattermost mattermostdb
```
Setup the Unix socket by adding the following line to /var/lib/postgres/data/pg_hba.conf:
```
local    mattermostdb    mattermost    peer
```
Restart postgresql.service.

Run the setup using:

sudo -u mattermost psql --dbname=mattermostdb

Configuring Mattermost

Mattermost is configured in /etc/webapps/mattermost/config.json. Strings need to be quoted.
The DriverName setting: mysql for MySQL and postgres for PostgreSQL.

The DataSource:
- For MySQL, set it to mmuser:mmuser_password@unix(/run/mysqld/mysqld.sock)/mattermostdb?charset=utf8mb4,utf8.
- For PostgreSQL
  - TCP socket: postgres://mmuser:mmuser_password@127.0.0.1:5432/mattermostdb?sslmode=disable&connect_timeout=10
  - Unix socket: postgres:///mattermostdb?host=/run/postgresql, where mattermostdb is the name of the database and /run/postgresql is the directory containing the Unix socket.