Scale one or multiple replicated services
API 1.24+ The client and daemon API must both be at least 1.24 to use this command. Use the docker version command on the client to check your client and daemon API versions.
Swarm This command works with the Swarm orchestrator.
docker service scale SERVICE=REPLICAS [SERVICE=REPLICAS...]
| Name, shorthand | Default | Description |
--detach , -d |
API 1.29+ Exit immediately instead of waiting for the service to converge |
| 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 or task |
| 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 rollback | Revert changes to a service’s configuration |
| docker service scale | Scale one or multiple replicated services |
| docker service update | Update 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.
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
b4g08uwuairexjub6ome6usqh
$ 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
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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https://docs.docker.com/engine/reference/commandline/service_scale/