Public | Automated Build

Last pushed: a year ago
Short Description
OpenShift PostgreSQL image with option to disable replication to run with small persistent volumes.
Full Description

PostgreSQL Docker image

This repository contains Dockerfiles for PostgreSQL images for general usage and OpenShift.
Users can choose between RHEL and CentOS based images.

Environment variables and volumes

The image recognizes the following environment variables that you can set during
initialization by passing -e VAR=VALUE to the Docker run command.

Variable name Description
POSTGRESQL_USER User name for PostgreSQL account to be created
POSTGRESQL_PASSWORD Password for the user account
POSTGRESQL_DATABASE Database name
POSTGRESQL_ADMIN_PASSWORD Password for the postgres admin account (optional)

The following environment variables influence the PostgreSQL configuration file. They are all optional.

Variable name Description Default
POSTGRESQL_MAX_CONNECTIONS The maximum number of client connections allowed 100
POSTGRESQL_MAX_PREPARED_TRANSACTIONS Sets the maximum number of transactions that can be in the "prepared" state. If you are using prepared transactions, you will probably want this to be at least as large as max_connections 0
POSTGRESQL_SHARED_BUFFERS Sets how much memory is dedicated to PostgreSQL to use for caching data 32M
POSTGRESQL_EFFECTIVE_CACHE_SIZE Set to an estimate of how much memory is available for disk caching by the operating system and within the database itself 128M
POSTGRESQL_ENABLE_REPLICATION Streaming replication is enabled by default and requires up to 6.25 GiB additional disk space. Set to 0 if you don't need replication and want to run PostgreSQL with a small persistent volume. 1

You can also set the following mount points by passing the -v /host:/container flag to Docker.

Volume mount point Description
/var/lib/pgsql/data PostgreSQL database cluster directory

Notice: When mouting a directory from the host into the container, ensure that the mounted
directory has the appropriate permissions and that the owner and group of the directory
matches the user UID or name which is running inside the container.

Usage

For this, we will assume that you are using the openshift/postgresql-92-centos7 image.
If you want to set only the mandatory environment variables and not store the database
in a host directory, execute the following command:

$ docker run -d --name postgresql_database -e POSTGRESQL_USER=user -e POSTGRESQL_PASSWORD=pass -e POSTGRESQL_DATABASE=db -p 5432:5432 openshift/postgresql-92-centos7

This will create a container named postgresql_database running PostgreSQL with
database db and user with credentials user:pass. Port 5432 will be exposed
and mapped to the host. If you want your database to be persistent across container
executions, also add a -v /host/db/path:/var/lib/pgsql/data argument. This will be
the PostgreSQL database cluster directory.

If the database cluster directory is not initialized, the entrypoint script will
first run initdb
and setup necessary database users and passwords. After the database is initialized,
or if it was already present, postgres
is executed and will run as PID 1. You can stop the detached container by running
docker stop postgresql_database.

PostgreSQL auto-tuning

When the PostgreSQL image is run with the --memory parameter set and if there
are no values provided for POSTGRESQL_SHARED_BUFFERS and
POSTGRESQL_EFFECTIVE_CACHE_SIZE those values are automatically calculated
based on the value provided in the --memory parameter.

The values are calculated based on the
upstream
formulas. For the shared_buffers we use 1/4 of given memory and for the
effective_cache_size we set the value to 1/2 of the given memory.

PostgreSQL admin account

The admin account postgres has no password set by default, only allowing local
connections. You can set it by setting the POSTGRESQL_ADMIN_PASSWORD environment
variable when initializing your container. This will allow you to login to the
postgres account remotely. Local connections will still not require a password.

Changing passwords

Since passwords are part of the image configuration, the only supported method
to change passwords for the database user (POSTGRESQL_USER) and postgres
admin user is by changing the environment variables POSTGRESQL_PASSWORD and
POSTGRESQL_ADMIN_PASSWORD, respectively.

Changing database passwords through SQL statements or any way other than through
the environment variables aforementioned will cause a mismatch between the
values stored in the variables and the actual passwords. Whenever a database
container starts it will reset the passwords to the values stored in the
environment variables.

Docker Pull Command
Owner
appuio
Source Repository

Comments (0)