moby--moby/docs/reference/commandline/update.md

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title = "update"
description = "The update command description and usage"
keywords = ["resources, update, dynamically"]
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parent = "smn_cli"
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## update

```markdown
Usage:  docker update [OPTIONS] CONTAINER [CONTAINER...]

Update configuration of one or more containers

Options:
      --blkio-weight value          Block IO (relative weight), between 10 and 1000
      --cpu-period int              Limit CPU CFS (Completely Fair Scheduler) period
      --cpu-quota int               Limit CPU CFS (Completely Fair Scheduler) quota
  -c, --cpu-shares int              CPU shares (relative weight)
      --cpuset-cpus string          CPUs in which to allow execution (0-3, 0,1)
      --cpuset-mems string          MEMs in which to allow execution (0-3, 0,1)
      --help                        Print usage
      --kernel-memory string        Kernel memory limit
  -m, --memory string               Memory limit
      --memory-reservation string   Memory soft limit
      --memory-swap string          Swap limit equal to memory plus swap: '-1' to enable unlimited swap
      --restart string              Restart policy to apply when a container exits
```

The `docker update` command dynamically updates container configuration.
You can use this command to prevent containers from consuming too many resources
from their Docker host.  With a single command, you can place limits on
a single container or on many. To specify more than one container, provide
space-separated list of container names or IDs.

With the exception of the `--kernel-memory` value, you can specify these
options on a running or a stopped container. You can only update
`--kernel-memory` on a stopped container or on a running container with
kernel memory initialized. For example, if you started a container with
command:

    # docker run -ti --name test --kernel-memory 50M ubuntu bash

You can update kernel memory of this running container:

    # docker update --kernel-memory 80M test

If you started a container without kernel memory initialized:

    # docker run -ti --name test2 --memory 300M ubuntu bash

Update kernel memory of running container `test2` will fail, you can only
stop the container and update kernel memory then. The next time you
restart it, the container uses the new value.

Another configuration you can change with this command is restart policy,
new restart policy will take effect instantly after you run `docker update`
on a container.

## EXAMPLES

The following sections illustrate ways to use this command.

### Update a container with cpu-shares=512

To limit a container's cpu-shares to 512, first identify the container
name or ID. You can use **docker ps** to find these values. You can also
use the ID returned from the **docker run** command.  Then, do the following:

```bash
$ docker update --cpu-shares 512 abebf7571666
```

### Update a container with cpu-shares and memory

To update multiple resource configurations for multiple containers:

```bash
$ docker update --cpu-shares 512 -m 300M abebf7571666 hopeful_morse
```

### Update a container's restart policy

To update restart policy for one or more containers:
```bash
$ docker update --restart=on-failure:3 abebf7571666 hopeful_morse
```