intermediate/workshop/DockerCompose/scale_command.md
The docker-compose scale <service name> = <no of instances> sets the number of containers to run for a service.
<b>NOTE:</b>The scale command is deprecated, instead Use the up command with the --scale flag.
docker-compose up --scale <service name> = <no of instances>
version: '3.1'
services:
redis-master:
image: redis:latest
container_name: webserver
restart: unless-stopped
ports:
- "6379"
redis-slave:
image: gcr.io/google_samples/gb-redisslave:v1
ports:
- "6379"
environment:
- GET_HOSTS_FROM=dns
frontend:
image: gcr.io/google-samples/gb-frontend:v3
ports:
- "80:80"
environment:
- GET_HOSTS_FROM=dns
$ docker-compose up -d
$ docker-compose ps
Name Command State Ports
-------------------------------------------------------------------------------------
root_frontend_1 apache2-foreground Up 0.0.0.0:80->80/tcp
root_redis-slave_1 /entrypoint.sh /bin/sh -c ... Up 0.0.0.0:32769->6379/tcp
webserver docker-entrypoint.sh redis ... Up 0.0.0.0:32768->6379/tcp
$ docker-compose ps --services
redis-slave
frontend
redis-master
$ocker-compose scale redis-slave=3
Starting root_redis-slave_1 ... done
Creating root_redis-slave_2 ... done
Creating root_redis-slave_3 ... done
$ docker-compose ps
Name Command State Ports
----------------------------------------------------------------------------------------
root_frontend_1 apache2-foreground Up 0.0.0.0:80->80/tcp
root_redis-slave_1 /entrypoint.sh /bin/sh -c ... Up 0.0.0.0:32772->6379/tcp
root_redis-slave_2 /entrypoint.sh /bin/sh -c ... Up 0.0.0.0:32775->6379/tcp
root_redis-slave_3 /entrypoint.sh /bin/sh -c ... Up 0.0.0.0:32776->6379/tcp
webserver docker-entrypoint.sh redis ... Up 0.0.0.0:32768->6379/tcp
<b>NOTE:</b> Host machine can only bind an unallocated port to the container, so trying scale service which is mounted to host will fail.
Next >> Lab #19: Exec Command