docker service scale

Estimated reading time: 2 minutes


Scale one or multiple replicated services



Parent command

Command Description
docker service Manage services
Command Description
docker service create Create a new service
docker service inspect Display detailed information on one or more services
docker service logs Fetch the logs of a service
docker service ls List services
docker service ps List the tasks of one or more services
docker service rm Remove one or more services
docker service scale Scale one or multiple replicated services
docker service update Update a service


Scale a service

The scale command enables you to scale one or more replicated services either up or down to the desired number of replicas. This command cannot be applied on services which are global mode. The command will return immediately, but the actual scaling of the service may take some time. To stop all replicas of a service while keeping the service active in the swarm you can set the scale to 0.

For example, the following command scales the “frontend” service to 50 tasks.

$ docker service scale frontend=50
frontend scaled to 50

The following command tries to scale a global service to 10 tasks and returns an error.

$ docker service create --mode global --name backend backend:latest
$ docker service scale backend=10
backend: scale can only be used with replicated mode

Directly afterwards, run docker service ls, to see the actual number of replicas.

$ docker service ls --filter name=frontend

ID            NAME      MODE        REPLICAS  IMAGE
3pr5mlvu3fh9  frontend  replicated  15/50     nginx:alpine

You can also scale a service using the docker service update command. The following commands are equivalent:

$ docker service scale frontend=50
$ docker service update --replicas=50 frontend

Scale multiple services

The docker service scale command allows you to set the desired number of tasks for multiple services at once. The following example scales both the backend and frontend services:

$ docker service scale backend=3 frontend=5
backend scaled to 3
frontend scaled to 5

$ docker service ls
ID            NAME      MODE        REPLICAS  IMAGE
3pr5mlvu3fh9  frontend  replicated  5/5       nginx:alpine
74nzcxxjv6fq  backend   replicated  3/3       redis:3.0.6
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