tmp-postgres

tmp-postgres provides functions for creating a temporary postgres instance. By default it will create a temporary data directory and a temporary directory for a UNIX domain socket for postgres to listen on.

Here is an example using the exception-safe 'with' function:

with $ \db -> bracket
  (connectPostgreSQL (toConnectionString db))
  close $
  \conn -> execute_ conn "CREATE TABLE foo (id int)"

To extend or override the defaults use withConfig (or startConfig).

tmp-postgres ultimately calls initdb (optionally) , postgres and createdb (optionally).

All of the command line, environment variables and configuration files that are generated by default for the respective executables can be extended.

In general tmp-postgres is useful if you want a clean temporary postgres and do not want to worry about clashing with an existing postgres instance (or needing to ensure postgres is already running).

Here are some different use cases for tmp-postgres and their respective configurations:

• The default 'with' and 'start' functions can be used to make a sandboxed temporary database for testing.
• By disabling initdb one could run a temporary isolated postgres on a base backup to test a migration.
• By using the 'stopPostgres' and 'withRestart' functions one can test backup strategies.

WARNING!! Ubuntu's PostgreSQL installation does not put initdb on the PATH. We need to add it manually. The necessary binaries are in the /usr/lib/postgresql/VERSION/bin/ directory, and should be added to the PATH

echo "export PATH=$PATH:/usr/lib/postgresql/VERSION/bin/" >> /home/ubuntu/.bashrc

Installation

macOS

$ brew install postgres
$ stack install tmp-postgres

Ubuntu

Ubuntu's PostgreSQL installation does not put initdb on the PATH. We need to add it manually.

$ sudo apt-get install postgresql-VERSION
$ echo "export PATH=$PATH:/usr/lib/postgresql/VERSION/bin/" >> /home/ubuntu/.bashrc
$ stack install tmp-postgres

GitHub Actions

Assuming you are using one of the standard workflow containers, simply add workflow steps which install postgresql as above. For example,

jobs:
  build:
    runs-on: ubuntu-18.04
    steps:
      - name: "Install postgresql"
        run: "sudo apt-get update && sudo apt-get install postgresql-10"

      # ...

      - name: "Run test"
        run: |
          export PATH=$PATH:/usr/lib/postgresql/10/bin
          stack test