hasura-postgres-schema-sync

This repo contains a service designed to keep a Hasura instance in sync with a Postgres database.

Concept

You already have a Postgres instance and a Hasura instance and you want something to do the hard work of keeping Hasura aware of your changing database schema.

Enter hasura-postgres-schema-sync, a small Python service that regularly walks the schema of the given Postgres database, converts it to Hasura metadata and updates Hasura with it.

Usage

Demo

Prerequisites

• Docker w/ Docker Compose

Steps

Use the helper script that orchestrates the Docker Compose interactions:

./run.sh

This will spin up the following Docker Compose services:

• postgres
  • A Postgres instance w/ PostGIS
• postgres-bootstrap
  • A one-shot container to restore some contrived SQL to postgres for testing
• hasura-bootstrap
  • A one-shot container to prepare the Hasura metadata and migrations volumes
• hasura
  • A Hasura instance
• hasura-postgres-schema-sync
  • The service this repo is all about
• hasura-postgres-schema-sync-test
  • A container for integration testing hasura-postgres-schema-sync

If you like, you can then run the integration tests:

./test.sh

You should see pytest output reflecting some passed tests.

Finally, navigate to http://localhost:8080, login with "Password1" and attempt a query; e.g.:

query ThingLocationStatByThing {
  thing {
    thing_location_stat_by_thing_uuid(limit: 10, order_by: {timestamp: desc}) {
      location
      timestamp
    }
    uuid
  }
}

Deployment

Prerequisites

• A Postgres database
• A Hasura instance
• Docker

Steps

We publish hasura-postgres-schema-sync to the FTP Solutions Docker Hub organisation, so that's the easiest way to get started.

Use docker run to run a temporary container pointed at your Postgres database and Hasura instance:

docker run --rm -it \
  -e POSTGRES_SCHEMA=public \
  -e POSTGRES_HOST=your-postgres-database.org.au \
  -e POSTGRES_PORT=5432 \
  -e POSTGRES_USER=postgres \
  -e POSTGRES_PASSWORD=Password1 \
  -e POSTGRES_DB=some_database \
  -e HASURA_HOST=your-hasura-instance.org.au \
  -e HASURA_PORT=8080 \
  -e HASURA_USER=admin \
  -e HASURA_PASSWORD=Password1 \
  ftpsolutions/hasura-postgres-schema-sync:main

This will leave you with an attached container, attempting to sync your Postgres database with your Hasura instance on a 10 second schedule.