How to increase max_connection in github action Postgres

There is a straightforward way to do it, but you can achieve it by installing the pg client and configuration the container when the service starts. The exact steps are documented in this blog post.

The relevant code:

steps:
  - name: Install postgresql-client
    run: |
      sudo apt-get update
      sudo apt-get install --yes postgresql-client

  - name: Connect to PostgreSQL with CLI
    run: psql -c 'SELECT VERSION();'

  - name: Show PostgreSQL config file
    run: psql -c 'SHOW config_file;'

  - name: Alter max connections
    run: |
      docker exec -i postgres bash << EOF
        sed -i -e 's/max_connections = 100/max_connections = 1000/' /var/lib/postgresql/data/postgresql.conf
        sed -i -e 's/shared_buffers = 128MB/shared_buffers = 2GB/' /var/lib/postgresql/data/postgresql.conf
      EOF
      docker restart --time 0 postgres
      sleep 5

  - name: Show max connections
    run: psql -c 'SHOW max_connections;'

As there isn't an option to set a custom command for Docker services, this remains the most straightforward way of doing it.

For postgres 16 and higher you can use POSTGRES_INITDB_ARGS:

env:
  POSTGRES_INITDB_ARGS: "-c max_connections=1500"

Note: This only is respected on the first start of the container (which is no problem on GitHub Actions).