ravensys/postgresql repository overview

⁠PostgreSQL 9.6 SQL database server Docker image

This container image includes PostgreSQL database server version 9.6 based on CentOS.

The CentOS image is available on Docker Hub⁠ as ravensys/postgresql:9.6-centos7.

⁠Description

This container image provides a containerized packaging of the PostgreSQL postgres daemon and client application. The postgres server daemon accepts connections from clients and provides access to content from PostgreSQL databases on behalf of the clients. You can find more information on the PostgreSQL project from the project Web site (https://www.postgresql.org/⁠).

⁠Usage

If the database data directory is not initialized, the entrypoint script will first run initdb and setup necessary database users and password. After database is initialized, or if it was already present, postgres is executed and will run as PID 1.

• Simple user with database

  This will create a container named postgresql_database running PostgreSQL with database named db and user with credentials user:pass. Port 5432 will be exposed and mapped to host.

  $ docker run -d --name postgresql_database -e POSTGRESQL_USER=user -e POSTGRESQL_PASSWORD=pass -e POSTGRESQL_DATABASE=db -p 5432:5432 ravensys/postgresql:9.6-centos7
  

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• Simple user without database

  This will create a container named postgresql_database running PostgreSQL with user with credentials user:pass and admin with credentials postgres:rootpass. Port 5432 will be exposed and mapped to host.

  $ docker run -d --name postgresql_database -e POSTGRESQL_USER=user -e POSTGRESQL_PASSWORD=pass -e POSTGRESQL_ADMIN_PASSWORD=rootpass -p 5432:5432 ravensys/postgresql:9.6-centos7
  

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• Only admin account

  This will create a container named postgresql_database running PostgreSQL with admin with credentials postgres:rootpass. Port 5432 will be exposed and mapped to host.

  $ docker run -d --name postgresql_database -e POSTGRESQL_ADMIN_PASSWORD=rootpass -p 5432:5432 ravensys/postgresql:9.6-centos7
  

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  Alternatively the same configuration can be achieved by setting POSTGRESQL_USER environment variable to postgres.

  $ docker run -d --name postgresql_database -e POSTGRESQL_USER=postgres -e POSTGRESQL_PASSWORD=rootpass -p 5432:5432 ravensys/postgresql:9.6-centos7
  

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To make database data persistent across container executions add -v /host/db/path:/var/lib/pgsql/data argument to the Docker run command.

To stop detached container simply run docker stop postgresql_database.

⁠Environment variables

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

Following environment variables influence PostgreSQL configuration file. They are all OPTIONAL.

⁠Secrets

The image recognizes following secrets which can be created by running echo <value> | docker secret create <name>.

Default secret name can be changed by setting respective environment variable during initialization, value represents a relative path to a file located in secrets volume.

Notice: Secrets takes precedence over environment variables, if both secret and environment variable are set, the value from secret is used.

⁠Volumes

The following mount points can be set by passing -v /host/path:/container/path to the Docker run command.

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

⁠PostgreSQL auto-tuning

When PostgreSQL image is run with the --memory parameter set and if there are no values provided for these environment variables, their values will be automatically calculated based on available memory.

⁠PostgreSQL admin account

The admin account postgres has no password set by default, only allowing local connections. To allow postgres user login remotely the POSTGRESQL_ADMIN_PASSWORD environment variable must be set when initializing container. Local connections will still not require password.

⁠PostgreSQL unprivileged account

The unprivileged user account with POSTGRESQL_USER name is created, authenticated by password set in POSTGRESQL_PASSWORD, with owner privileges to database POSTGRESQL_DATABASE.

⁠Changing passwords

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

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

⁠Post-initialization scripts

Image initialization process can by extended by placing sourcable shell scripts, these must have a .sh extension, into post-initialization drop-in /usr/share/container-entrypoint/postgresql/post-init.d directory.

• Mount volume with post-init scripts

  To propagate post-initialization scripts from host into container add volume mount -v /path/to/post-init/scripts:/usr/share/container-entrypoint/postgresql/post-init.d argument to the Docker run command.

  $ docker run -d --name postgresql_database -v /path/to/post-init/scripts:/usr/share/container-entrypoint/postgresql/post-init.d -e POSTGRESQL_ADMIN_PASSWORD=rootpass -p 5432:5432 ravensys/postgresql:9.6-centos7
  

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• Extend image with post-init scripts

  This Dockerfile will create a Docker image based on ravensys/postgresql:9.6-centos7 with built-in post-initialization scripts from directory post-init-scripts.

  FROM ravensys/postgresql:9.6-centos7
  
  COPY post-init-scripts /usr/share/container-entrypoint/postgresql/post-init.d
  

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⁠Changing default locale

This Dockerfile will create a Docker image based on ravensys/postgresql:9.6-centos7 with default locale set to de_DE.UTF-8.

FROM ravensys/postgresql:9.6-centos7

RUN localedef -f UTF-8 -i de_DE de_DE.UTF-8
ENV LANG de_DE.UTF-8

⁠Troubleshooting

The container initialization scripts logs to the standard output, so these are available in container log. This log can be examined by running:

$ docker logs <container>

The postgres daemon in container logs are stored in pg_log directory located in postgresql data directory.

⁠See also

Dockerfile and other sources for this container image are available on https://github.com/ravensys/container-postgresql⁠.