Postgresql 9.3 on Centos 7 with custom PGDATA - linux

Question

I am trying to set up Postgresql 9.3 server on Centos 7 (installation via yum) inside a custom directory, which in my case is an encrypted partition (/custom_container/database) that is mounted on startup. For a certain reason Postgresql does not behave like it should in the manual and makes an error on service startup.
Note: It does not want to accept the PGDATA environment variable which I set, and when running
su - postgres -c '/usr/pgsql-9.3/bin/initdb'
(given that the PGDATA directory is owned by postgres:postgres) the cluster gets initialized inside the default directory /var/lib/pgsql/9.3/data/
The only way to change that is using
su - postgres -c '/usr/pgsql-9.3/bin/initdb --pgdata=$PGDATA'
Which initializes the directory inside the custom container I am using. This is something I could not figure out, as the docs say that PGDATA variable is taken on default.
Problem: When running
service postgresql-9.3 start
I get an error with the log
postgresql-9.3.service - PostgreSQL 9.3 database server
Loaded: loaded (/usr/lib/systemd/system/postgresql-9.3.service; disabled)
Active: failed (Result: exit-code) since Mon 2014-11-10 15:24:15 CET; 1s ago
Process: 2785 ExecStartPre=/usr/pgsql-9.3/bin/postgresql93-check-db-dir ${PGDATA} (code=exited, status=1/FAILURE)
Nov 10 15:24:15 CentOS-70-64-minimal systemd[1]: Starting PostgreSQL 9.3 database server...
Nov 10 15:24:15 CentOS-70-64-minimal postgresql93-check-db-dir[2785]: "/var/lib/pgsql/9.3/data/" is missing or empty.
Nov 10 15:24:15 CentOS-70-64-minimal postgresql93-check-db-dir[2785]: Use "/usr/pgsql-9.3/bin/postgresql93-setup initdb" to initialize t...ster.
Nov 10 15:24:15 CentOS-70-64-minimal postgresql93-check-db-dir[2785]: See %{_pkgdocdir}/README.rpm-dist for more information.
Nov 10 15:24:15 CentOS-70-64-minimal systemd[1]: postgresql-9.3.service: control process exited, code=exited status=1
Nov 10 15:24:15 CentOS-70-64-minimal systemd[1]: Failed to start PostgreSQL 9.3 database server.
Nov 10 15:24:15 CentOS-70-64-minimal systemd[1]: Unit postgresql-9.3.service entered failed state.
Which means that Postgresql, even though the cluster is initialized in the new $PGDATA directory (/custom_container/database) still looks for the cluster in /var/lib/pgsql/9.3/data/
Did anyone experience this Postgresql behavior before? Could it be that I forgot certain configuration options or that the problem comes from Postgresql installation?
Thank you in advance!

Answer 1

It appears the real problem was setting the environment variables, which I got working in the following thread:
Centos 7 environment variables for Postgres service
The issue is the PGDATA variable set inside the custom /etc/systemd/system/postgresql-9.3.service which should be created from the contents of /usr/lib/systemd/system/postgresql-9.3.service which uses the default PGDATA var.

Answer 2

You need to create a custom postgresql.service file in /etc/systemd/system/, which overrides the default PGDATA environment variable. Your custom service file can .include the default postgresql service file, so you only need to add what you want to change. That way, upgrades can still modify/improve? stuff in the default service file, while your change is preserved.
This is how I just did it in Centos 7:
cat <<END >/etc/systemd/system/postgresql.service
.include /lib/systemd/system/postgresql.service
[Service]
Environment=PGDATA=/mnt/postgres/data ## <== SET THIS TO YOUR WANTED $PGDATA
END
systemctl daemon-reload
systemctl restart postgresql.service
Verify :
ps -ax | grep [p]ostgres
Update:
Rather than manually creating the file and adding the .include line, you can also use the systemd built-in way:
systemctl edit postgresql.service
This will open your default editor and save your changes to /etc/systemd/system/postgresql.service.d/override.conf

Answer 3

try this:
## Login with postgres user
su - postgres
export PGDATA=/your_path/data
pg_ctl -D $PGDATA start &

Answer 4

I think the most "CentOS 7 way" to do it is to copy the service file:
sudo cp /usr/lib/systemd/system/postgresql-9.6.service /etc/systemd/system/postgresql-9.6.service
Then edit the file /etc/systemd/system/postgresql-9.6.service:
# Location of database directory
Environment=PGDATA=/mnt/volume/var/lib/pgsql/9.6/data/
Then start it sudo systemctl start postgresql-9.6 and verify:
# sudo ps -ax | grep postmaster
32100 ? Ss 0:00 /usr/pgsql-9.6/bin/postmaster -D /mnt/volume/var/lib/pgsql/9.6/data/

Answer 5

Try to edit file /etc/init.d/postgresql-9.3:
PGDATA=/your/custom/path