How to interact with your project’s database

The database for your Divio project runs:

In either case, you will mostly only need to interact with the database using the tools provided by your project’s runtime stack (e.g. Django). However, if you need to interact with it directly, the option exists.

Interact with the local database

This is the recommended and most useful way to interact with the project’s database.

From the project’s local Django web container

Using dbshell

Run:

docker-compose run --rm web python ./manage.py dbshell

Connecting to a Postgres database manually

You can also make the connection manually from within the web container, for example:

docker-compose run --rm web psql -h postgres -U postgres db

As well as psql you can run commands such as pg_dump and pg_restore. This is useful for a number of common operations, below.

Your project may not have the psql client installed already, in which case you will need to install it first. See How to install system packages in a project.

Using docker exec

Another way of interacting with the database is via the database container itself, using docker exec. This requires that the database container already be up and running.

For example, if your database container is called example_db_1:

docker exec -i example_db_1 psql -U postgres

From your host environment

If you have a preferred database management tool that runs on your own computer, you can also connect to the database from outside the application.

Expose the database’s port

In order to the connect to the database from a tool running directly on your own machine, you will need to expose its port (5432 by default for Postgres).

Add a ports section to the db service in docker-compose.yml and map the port to your host. For Postgres, for example:

db:
    image: postgres:9.6
    ports:
        - 5432:5432

This means that external traffic reaching the container on port 5432 will be routed to port 5432 internally.

The ports are <host port>:<container port> - you can choose another host port if you are already using that port on your host.

Now restart the db container with: docker-compose up -d db

Connect to a Postgres database

You will need to use the following details:

  • port: 5432

  • username: postgres

  • password: not required

  • database: db

Access the database using your Postgres tool of choice. Note that you must specify the host address, 127.0.0.1.

For example, if you’re using the psql command line tool, you can connect to the project database with:

psql -h 127.0.0.1 -U postgres db

Interact with the Cloud database

Note

It’s often more appropriate to pull down the Cloud database to a local project to interact with it there:

divio project pull db live  # or test

See the divio project command reference for more on using these commands.

From the project’s Cloud application container

Note

SSH access to an application container on the Cloud is available on Managed Cloud projects only.

Log into your Cloud project’s container (Test or Live) over SSH.

Using dbshell in a Django project

Run:

./manage.py dbshell

This will drop you into a command-line client, connected to your database.

Connecting to a database manually

You can also make the connection manually. Run env to list your environment variables. Amongst them you’ll find DATABASE_URL, which will be in the form:

schema://<user name>:<password>@<address>:<port>/<name>

You can use these credentials in the appropriate client, e.g. psql.

From your own computer

Access to cloud databases other than from the associated application containers is not possible - it is restricted, for security reasons, to containers running on our own infrastructure.

Change the local database engine version

Sometimes, you will need to change the database engine, or its version number, that your local project uses - for example if the cloud database is updated or changed. If the two database engines are not the same, you may run into problems.

The local database engine is specified by the image option in the db service in your project’s docker-compose.yml file, for example:

db:
    image: postgres:9.6-alpine

Should you need to change this, that line should be updated - for example if the Cloud database is now running Postgres 11:

db:
    image: postgres:11-alpine

Docker will use the new version the next time the local project is launched.

If you are not sure what image to use for the local database, Divio support will be able to advise you.

Important

In the Divio architecture, the docker-compose.yml file is not used for Cloud deployments, but only for the local server. The changes you make here will not affect the Cloud database.

Usage examples for common basic operations

It’s beyond the scope of this article to give general guidance on using the database, but these examples will help give you an idea of some typical operations that you might undertake while using Divio.

All the examples assume that you are interacting with the local database, running in its db container, and will use Postgres.

In each case, we launch the command from within the web container with docker-compose run --rm web and we specify:

  • host name: -h postgres

  • user name: -U postgres

Dump the database

Dump the database db to a file named database.dump:

docker-compose run --rm web pg_dump -h postgres -U postgres db > database.dump

Drop the database

Drop (delete) the database named db:

docker-compose run --rm web dropdb -h postgres -U postgres db

Create the database

Create a database named db:

docker-compose run --rm web createdb -h postgres -U postgres db

Apply the hstore extension

Apply the hstore extension (required on a newly-created local database) to the database named db:

docker-compose run --rm web psql -h postgres -U postgres db -c "CREATE EXTENSION hstore"

Restore the database

Restore a database named db from a file named database.dump:

docker-compose run --rm web pg_restore -h postgres -U postgres -d db database.dump --no-owner

Reset the database

To reset the database (with empty tables, but the schema in place) you would run the commands above to drop and create the database, create the the hstore extension, followed by a migration:

docker-compose run --rm web python manage.py migrate

Restore from a downloaded Cloud backup

Untar the downloaded backup.tar file. It contains a database.dump file. Copy the file to your local project directory, then run the commands above to drop and create the database, create the the hstore extension, and then restore from a file.