This repository contains Dockerfiles for PostgreSQL images for general usage and OpenShift. Users can choose between RHEL and CentOS based images.
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. This also sets the maximum number of prepared transactions. | 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 |
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.
For this, we will assume that you are using the centos/postgresql-94-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 centos/postgresql-94-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.
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.
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.
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.