How to know when postgres database is ready

January 1, 0001 database compose

Postgres provides an easy-to-use command called pg_isready to know exactly when to accept connections. Useful for orchestrating container dependencies, without maintaining custom scripts.

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database:
    image: postgres:14.3-alpine
    environment:
      - POSTGRES_USER=test
      - POSTGRES_PASSWORD=password
      - POSTGRES_DB=example
    ports:
      - '5432:5432'
    healthcheck:
      test: ['CMD-SHELL', 'pg_isready -U test -d example']
      interval: 5s
      timeout: 5s
      retries: 5

Bash script that can be used as a part of CI/CD pipeline job.

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#!/bin/sh
pg_uri="postgres://postgres:password@localhost:5432/example"
until pg_isready -h postgres-host -p 5432 -U postgres
do
  echo "Waiting for postgres at: $pg_uri"
  sleep 2;
done
# Now able to connect to postgres