When it comes working with a master - replica services Docker offers a scaling compose command which is very useful. Here I’m going to show you how to use it with an example.
- Docker Compose
Docker Scale Example
Let say that we have a compose file that holds a Redis service with a master and replica. Instead of coping the same configuration, let’s see how can you use
Here is an example of the Compose file:
version: '3' services: redis-master: image: redis:alpine ports: - "6379:6379" env_file: - .env volumes: - redis_data:/data ... redis-replica: image: redis:alpine ports: - 6379 env_file: - .env depends_on: - redis-master ...
Now if you want to have
1 master container and
3 replicas use the following command:
docker-compose up --scale redis-master=1 --scale redis-replica=3
It will start one container from the master and three from the replica.
scale command is very useful as you can replicate the same scenario that you are using on your server and see its behavior. Taking
Redis as a service was just an example, feel free to use the scale command to any service you want to deploy.
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