CentOS 7.2 Install PostgreSQL

按照官方的安装文档安装mattermost时，踩了一些坑，根据官方文档并结合自己的安装过程，重新整理了下mattermost的安装配置。 踩坑的原因：1.使用的CentOS版本为7.2,而官网的版本为7.1；2.CentOS 7之后有些命令跟7之前的不太一样。 3.官方文档关于pg的配置不够详细。（由于自己时pg小白，所以没能顺利搞下来，还是查资料配置pg）

Log in to the server that will host the database, and open a terminal window.

Download the PostgreSQL 9.4 Yum repository.

wget https://download.postgresql.org/pub/repos/yum/9.4/redhat/rhel-7-x86_64/pgdg-redhat94-9.4-3.noarch.rpm

Install the Yum repository from the file that you downloaded.

sudo yum localinstall pgdg-redhat94-9.4-3.noarch.rpm

Install PostgreSQL.

sudo yum install postgresql94-server postgresql94-contrib

Initialize the database.

sudo /usr/pgsql-9.4/bin/postgresql94-setup initdb

Set PostgreSQL to start on boot.

sudo systemctl postgresql-9.4.service enable

Start the PostgreSQL server.

sudo systemctl start postgresql-9.4.service

Disable firewall

sudo systemctl disable  firewalld.service

Stop firewall

sudo systemctl stop firewalld.service

Switch to the postgres Linux user account that was created during the installation.

sudo --login --user postgres

Start the PostgreSQL interactive terminal.

psql

Create the Mattermost user ‘mmuser’.

postgres=# CREATE USER mmuser WITH PASSWORD 'mattermost';

Grant the user access to the Mattermost database.

postgres=# GRANT ALL PRIVILEGES ON DATABASE mattermost to mmuser;

Exit the PostgreSQL interactive terminal.

postgre=# \q

Log out of the postgres account.

exit

Allow Postgres to listen on all assigned IP Addresses.

vim /var/lib/pgsql/9.4/data/postgresql.conf
Find the following line:
\#listen_addresses = 'localhost'
Uncomment the line and change localhost to *:
listen_addresses = '*'

If the Mattermost server is on a separate machine, modify the file pg_hbe.conf to allow the Mattermost server to communicate with the database.

• vim /var/lib/pgsql/9.4/data/pg_hba.conf
• update pg_hba.conf config

restart pgsql

**systemctl restart  postgresql-9.4.service**

Verify that you can connect with the user mmuser

psql --host=localhost --dbname=mattermost --username=mmuser --password
The PostgreSQL interactive terminal starts. To exit the PostgreSQL interactive 	terminal, type \q and press Enter.