What is PostgreSQL?

PostgreSQL is an object-relational database management system (ORDBMS) with an emphasis on extensibility and on standards-compliance [source].

TLDR

docker run --name postgresql -e POSTGRES_PASSWORD=password123 bitnami/postgresql

Docker Compose

postgresql:
  image: bitnami/postgresql
  environment:
    - POSTGRES_PASSWORD=password123

Get this image

The recommended way to get the Bitnami PostgreSQL Docker Image is to pull the prebuilt image from the Docker Hub Registry.

docker pull bitnami/postgresql:latest

To use a specific version, you can pull a versioned tag. You can view the list of available versions in the Docker Hub Registry.

docker pull bitnami/postgresql:[TAG]

If you wish, you can also build the image yourself.

git clone https://github.com/bitnami/bitnami-docker-postgresql.git
cd bitnami-docker-postgresql
docker build -t bitnami/postgresql .

Persisting your database

If you remove the container all your data will be lost, and the next time you run the image the database will be reinitialized. To avoid this loss of data, you should mount a volume that will persist even after the container is removed.

Note! If you have already started using your database, follow the steps on backing up and restoring to pull the data from your running container down to your host.

The PostgreSQL image exposes a volume at /bitnami/postgresql/data, you can mount a directory from your host to serve as the data store. If the directory you mount is empty, the database will be initialized.

docker run -v /path/to/data:/bitnami/postgresql/data bitnami/postgresql

or using Docker Compose:

postgresql:
  image: bitnami/postgresql
  volumes:
    - /path/to/data:/bitnami/postgresql/data

Linking

If you want to connect to your PostgreSQL server inside another container, you can use the linking system provided by Docker.

Connecting a PostgreSQL client container to the PostgreSQL server container

Step 1: Run the PostgreSQL image with a specific name

The first step is to start our PostgreSQL server.

Docker's linking system uses container ids or names to reference containers. We can explicitly specify a name for our PostgreSQL server to make it easier to connect to other containers.

docker run --name postgresql -e POSTGRES_PASSWORD=password123 bitnami/postgresql

Step 2: Run PostgreSQL image as a client and link to our server

Now that we have our PostgreSQL server running, we can create another container that links to it by giving Docker the --link option. This option takes the id or name of the container we want to link it to as well as a hostname to use inside the container, separated by a colon. For example, to have our PostgreSQL server accessible in another container with server as it's hostname we would pass --link postgresql:server to the Docker run command.

The Bitnami PostgreSQL Docker Image also ships with a PostgreSQL client, but by default it will start a server. To start the client instead, we can override the default command Docker runs by stating a different command to run after the image name.

docker run --rm -it --link postgresql:server bitnami/postgresql psql -h server -U postgres

We started the PostgreSQL client passing in the -h option that allows us to specify the hostname of the server, which we set to the hostname we created in the link.

Note! You can also run the PostgreSQL client in the same container the server is running in using the Docker exec command.

docker exec -it postgresql psql -U postgres

Linking with Docker Compose

Step 1: Add a PostgreSQL entry in your docker-compose.yml

Copy the snippet below into your docker-compose.yml to add PostgreSQL to your application.

postgresql:
  image: bitnami/postgresql
  environment:
    - POSTGRES_PASSWORD=password123

Step 2: Link it to another container in your application

Update the definitions for containers you want to access your PostgreSQL server from to include a link to the postgresql entry you added in Step 1.

myapp:
  image: myapp
  links:
    - postgresql:postgresql

Inside myapp, use postgresql as the hostname for the PostgreSQL server.

Configuration

Setting the root password on first run

In the above commands you may have noticed the use of the POSTGRES_PASSWORD environment variable. Passing the POSTGRES_PASSWORD environment variable when running the image for the first time will set the password of the postgres user to the value of POSTGRES_PASSWORD.

docker run --name postgresql -e POSTGRES_PASSWORD=password123 bitnami/postgresql

or using Docker Compose:

postgresql:
  image: bitnami/postgresql
  environment:
    - POSTGRES_PASSWORD=password123

Note! The postgres user is a superuser and has full administrative access to the PostgreSQL database.

Creating a database on first run

By passing the POSTGRES_DB environment variable when running the image for the first time, a database will be created. This is useful if your application requires that a database already exists, saving you from having to manually create the database using the PostgreSQL client.

docker run --name postgresql -e POSTGRES_DB=my_database bitnami/postgresql

or using Docker Compose:

postgresql:
  image: bitnami/postgresql
  environment:
    - POSTGRES_DB=my_database

Creating a database user on first run

You can also create a restricted database user that only has permissions for the database created with the POSTGRES_DB environment variable. To do this, provide the POSTGRES_USER environment variable.

docker run --name postgresql -e POSTGRES_USER=my_user -e POSTGRES_PASSWORD=password123 -e POSTGRES_DB=my_database bitnami/postgresql

or using Docker Compose:

postgresql:
  image: bitnami/postgresql
  environment:
    - POSTGRES_USER=my_user
    - POSTGRES_PASSWORD=password123
    - POSTGRES_DB=my_database

Note! When POSTGRES_USER is specified, the postgres user is not assigned a password and as a result you cannot login remotely to the PostgreSQL server as the postgres user.

Setting up a streaming replication

A Streaming replication cluster can easily be setup with the Bitnami PostgreSQL Docker Image using the following environment variables:

• POSTGRES_MODE: Replication mode. Possible values master/slave (default: master).
• POSTGRES_REPLICATION_USER: Replication user. User is created on the master at first boot (default: none).
• POSTGRES_REPLICATION_PASSWORD: Replication users password. Password is set for POSTGRES_REPLICATION_USER on master on the first boot (default: none).
• POSTGRES_MASTER_HOST: Hostname/IP of replication master (parameter available only on slave).
• POSTGRES_MASTER_PORT: Port of replication master, defaults to 5432 (parameter available only on slave).

In a replication cluster you can have one master and zero or more slaves. Our default configuration allows a maximum of 16 slaves, you can change it in postgresql.conf if required.

When replication is enabled writes can occur only on the master while reads can take place on both the master or slaves. For best performance you should limit the reads to the slaves and use the master only for the writes.

Step 1: Create the replication master

The first step is to start the master.

docker run --name postgresql-master \
  -e POSTGRES_MODE=master \
  -e POSTGRES_USER=my_user \
  -e POSTGRES_PASSWORD=password123 \
  -e POSTGRES_DB=my_database \
  -e POSTGRES_REPLICATION_USER=my_repl_user \
  -e POSTGRES_REPLICATION_PASSWORD=my_repl_password \
  bitnami/postgresql

In this command we are configuring the container as the master using the POSTGRES_MODE=master parameter. Using the POSTGRES_REPLICATION_USER and POSTGRES_REPLICATION_PASSWORD parameters we are creating a replication user that will be used by the slaves to connect to the master and perform streaming replication.

By default a container is configured as a master. As a result you can drop the POSTGRES_MODE=master from the above command.

Step 2: Create the replication slave

Next we start a replication slave container.

docker run --name postgresql-slave \
  --link postgresql-master:master \
  -e POSTGRES_MODE=slave \
  -e POSTGRES_MASTER_HOST=master \
  -e POSTGRES_MASTER_PORT=5432 \
  -e POSTGRES_REPLICATION_USER=my_repl_user \
  -e POSTGRES_REPLICATION_PASSWORD=my_repl_password \
  bitnami/postgresql

In this command we are configuring the container as a slave using the POSTGRES_MODE=slave parameter. Before the replication slave is started, the POSTGRES_MASTER_HOST and POSTGRES_MASTER_PORT parameters are used by the slave container to connect to the master and replicate the initial database from the master. The POSTGRES_REPLICATION_USER and POSTGRES_REPLICATION_PASSWORD credentials are used to authenticate with the master.

Using the master docker link alias, the Bitnami PostgreSQL Docker image automatically fetches the replication paramaters from the master container, namely:

• POSTGRES_MASTER_HOST
• POSTGRES_MASTER_PORT
• POSTGRES_REPLICATION_USER
• POSTGRES_REPLICATION_PASSWORD

As a result you can drop all of these parameters from the slave.

docker run --name postgresql-slave \
  --link postgresql-master:master \
  -e POSTGRES_MODE=slave \
  bitnami/postgresql

With these two commands you now have a two node PostgreSQL master-slave streaming replication cluster up and running. When required you can add more slaves to the cluster without any downtime allowing you to scale the cluster horizontally.

Note: The cluster replicates the master in its entirety, which includes all users and databases.

If the master goes down you can reconfigure a slave to act as the master and begin accepting writes by creating the trigger file /tmp/postgresql.trigger.5432. For example the following command reconfigures postgresql-slave to act as the master:

docker exec postgresql-slave touch /tmp/postgresql.trigger.5432

Note: The configuration of the other slaves in the cluster needs to be updated so that they are aware of the new master. This would require you to restart the other slaves with --link postgresql-slave:master as per our examples.

With Docker Compose the master-slave replication can be setup using:

master:
  image: bitnami/postgresql
  environment:
    - POSTGRES_MODE=master
    - POSTGRES_USER=my_user
    - POSTGRES_PASSWORD=password123
    - POSTGRES_DB=my_database
    - POSTGRES_REPLICATION_USER=my_repl_user
    - POSTGRES_REPLICATION_PASSWORD=my_repl_password

slave:
  image: bitnami/postgresql
  links:
    - master:master
  environment:
    - POSTGRES_MODE=slave

Scale the number of slaves using:

docker-compose scale master=1 slave=3

The above command scales up the number of slaves to 3. You can scale down in the same way.

Note: You should not scale up/down the number of master nodes. Always have only one master node running.

Command-line options

The simplest way to configure your PostgreSQL server is to pass custom command-line options when running the image.

docker run bitnami/postgresql -N 1000

or using Docker Compose:

postgresql:
  image: bitnami/postgresql
  command: -N 1000

Further Reading:

• Server Command Options
• Caveats

Configuration file

This image looks for configuration in /bitnami/postgresql/conf. You can mount a volume there with your own configuration, or the default configuration will be copied to your volume if it is empty.

Step 1: Run the PostgreSQL image

Run the PostgreSQL image, mounting a directory from your host.

docker run --name postgresql -v /path/to/postgresql/conf:/bitnami/postgresql/conf bitnami/postgresql

or using Docker Compose:

postgresql:
  image: bitnami/postgresql
  volumes:
    - /path/to/postgresql/conf:/bitnami/postgresql/conf

Step 2: Edit the configuration

Edit the configuration on your host using your favorite editor.

vi /path/to/postgresql/conf/my.cnf

Step 3: Restart PostgreSQL

After changing the configuration, restart your PostgreSQL container for changes to take effect.

docker restart postgresql

or using Docker Compose:

docker-compose restart postgresql

Further Reading:

• Server Configuration
• Caveats

Caveats

The following options cannot be modified, to ensure that the image runs correctly.

-D /opt/bitnami/postgresql/data
--config_file=/opt/bitnami/postgresql/conf/postgresql.conf
--hba_file=/opt/bitnami/postgresql/conf/pg_hba.conf
--ident_file=/opt/bitnami/postgresql/conf/pg_ident.conf

Logging

The Bitnami PostgreSQL Docker Image supports two different logging modes: logging to stdout, and logging to a file.

Logging to stdout

The default behavior is to log to stdout, as Docker expects. These will be collected by Docker, converted to JSON and stored in the host, to be accessible via the docker logs command.

docker logs postgresql

or using Docker Compose:

docker-compose logs postgresql

This method of logging has the downside of not being easy to manage. Without an easy way to rotate logs, they could grow exponentially and take up large amounts of disk space on your host.

Logging to file

To log to file, run the PostgreSQL image, mounting a directory from your host at /bitnami/postgresql/logs. This will instruct the container to send logs to a postgresql.log file in the mounted volume.

docker run --name postgresql -v /path/to/postgresql/logs:/bitnami/postgresql/logs bitnami/postgresql

or using Docker Compose:

postgresql:
  image: bitnami/postgresql
  volumes:
    - /path/to/postgresql/logs:/bitnami/postgresql/logs

To perform operations (e.g. logrotate) on the logs, mount the same directory in a container designed to operate on log files, such as logstash.

Maintenance

Backing up your container

To backup your data, configuration and logs, follow these simple steps:

Step 1: Stop the currently running container

docker stop postgresql

or using Docker Compose:

docker-compose stop postgresql

Step 2: Run the backup command

We need to mount two volumes in a container we will use to create the backup: a directory on your host to store the backup in, and the volumes from the container we just stopped so we can access the data.

docker run --rm -v /path/to/backups:/backups --volumes-from postgresql busybox \
  cp -a /bitnami/postgresql /backups/latest

or using Docker Compose:

docker run --rm -v /path/to/backups:/backups --volumes-from `docker-compose ps -q postgresql` busybox \
  cp -a /bitnami/postgresql /backups/latest

Note! If you only need to backup database data, or configuration, you can change the first argument to cp to /bitnami/postgresql/data or /bitnami/postgresql/conf respectively.

Restoring a backup

Restoring a backup is as simple as mounting the backup as volumes in the container.

docker run -v /path/to/backups/latest/data:/bitnami/postgresql/data \
  -v /path/to/backups/latest/conf:/bitnami/postgresql/conf \
  -v /path/to/backups/latest/logs:/bitnami/postgresql/logs \
  bitnami/postgresql

or using Docker Compose:

postgresql:
  image: bitnami/postgresql
  volumes:
    - /path/to/backups/latest/data:/bitnami/postgresql/data
    - /path/to/backups/latest/conf:/bitnami/postgresql/conf
    - /path/to/backups/latest/logs:/bitnami/postgresql/logs

Upgrade this image

Bitnami provides up-to-date versions of PostgreSQL, including security patches, soon after they are made upstream. We recommend that you follow these steps to upgrade your container.

Step 1: Get the updated image

docker pull bitnami/postgresql:latest

or if you're using Docker Compose, update the value of the image property to bitnami/postgresql:latest.

Step 2: Stop and backup the currently running container

Before continuing, you should backup your container's data, configuration and logs.

Follow the steps on creating a backup.

Step 3: Remove the currently running container

docker rm -v postgresql

or using Docker Compose:

docker-compose rm -v postgresql

Step 4: Run the new image

Re-create your container from the new image, restoring your backup if necessary.

docker run --name postgresql bitnami/postgresql:latest

or using Docker Compose:

docker-compose start postgresql

Testing

This image is tested for expected runtime behavior, using the BATS testing framework. You can run the tests on your machine using the bats command.

bats test.sh

Contributing

We'd love for you to contribute to this container. You can request new features by creating an issue, or submit a pull request with your contribution.

Issues

If you encountered a problem running this container, you can file an issue. For us to provide better support, be sure to include the following information in your issue:

• Host OS and version
• Docker version (docker version)
• Output of docker info
• Version of this container (echo $BITNAMI_APP_VERSION inside the container)
• The command you used to run the container, and any relevant output you saw (masking any sensitive information)

License

Copyright 2015 Bitnami

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.