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Postgres Database acting as a Broadcast Channel

One of the containers that is handled inside the docker-compose.yml config is the broadcast channel.

When scaling the OPAL Server to multiple nodes and/or multiple workers, we use a broadcast channel to sync between all the instances of the OPAL Server.

services:
  broadcast_channel:
    image: postgres:alpine
    environment:
      - POSTGRES_DB=postgres
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres

With this configuration, you can specify what channel we want to subscribe too, and in this case, it's a PostgreSQL Database.

tip

If you run only a single worker it is not necessary to deploy a broadcast backend.

We do not recommend running a single worker in production.

These are the currently three supported broadcast backends:

  1. PostgreSQL
  2. Redis
  3. Kafka

The format of the broadcaster URI string OPAL_BROADCAST_URI is specified below for Postgres. A similar pattern will apply for Redis and Kafka.

environment:
  - OPAL_BROADCAST_URI=postgres://postgres:postgres@broadcast_channel:5432/postgres