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---
title: "update"
description: "The update command description and usage"
keywords: "resources, update, dynamically"
---
## update
```markdown
Usage: docker update [OPTIONS] CONTAINER [CONTAINER...]
Update configuration of one or more containers
Options:
--blkio-weight uint16 Block IO (relative weight), between 10 and 1000, or 0 to disable (default 0)
--cpu-period int Limit CPU CFS (Completely Fair Scheduler) period
--cpu-quota int Limit CPU CFS (Completely Fair Scheduler) quota
--cpu-rt-period int Limit the CPU real-time period in microseconds
--cpu-rt-runtime int Limit the CPU real-time runtime in microseconds
-c, --cpu-shares int CPU shares (relative weight)
--cpus decimal Number of CPUs (default 0.000)
--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
--pids-limit int Tune container pids limit (set -1 for unlimited)
--restart string Restart policy to apply when a container exits
```
## Description
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` option, you can specify these
options on a running or a stopped container. On kernel version older than
4.6, you can only update `--kernel-memory` on a stopped container or on
a running container with kernel memory initialized.
> **Warning**
>
> The `docker update` and `docker container update` commands are not supported
> for Windows containers.
{: .warning }
## Examples
The following sections illustrate ways to use this command.
### <a name="cpu-shares"></a> Update a container's cpu-shares (--cpu-shares)
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:
```console
$ docker update --cpu-shares 512 abebf7571666
```
### <a name="memory"></a> Update a container with cpu-shares and memory (-m, --memory)
To update multiple resource configurations for multiple containers:
```console
$ docker update --cpu-shares 512 -m 300M abebf7571666 hopeful_morse
```
### <a name="kernel-memory"></a> Update a container's kernel memory constraints (--kernel-memory)
You can update a container's kernel memory limit using the `--kernel-memory`
option. On kernel version older than 4.6, this option can be updated on a
running container only if the container was started with `--kernel-memory`.
If the container was started *without* `--kernel-memory` you need to stop
the container before updating kernel memory.
> **Note**
>
> The `--kernel-memory` option has been deprecated since Docker 20.10.
For example, if you started a container with this command:
```console
$ docker run -dit --name test --kernel-memory 50M ubuntu bash
```
You can update kernel memory while the container is running:
```console
$ docker update --kernel-memory 80M test
```
If you started a container *without* kernel memory initialized:
```console
$ docker run -dit --name test2 --memory 300M ubuntu bash
```
Update kernel memory of running container `test2` will fail. You need to stop
the container before updating the `--kernel-memory` setting. The next time you
start it, the container uses the new value.
Kernel version newer than (include) 4.6 does not have this limitation, you
can use `--kernel-memory` the same way as other options.
### <a name="restart"></a> Update a container's restart policy (--restart)
You can change a container's restart policy on a running container. The new
restart policy takes effect instantly after you run `docker update` on a
container.
To update restart policy for one or more containers:
```console
$ docker update --restart=on-failure:3 abebf7571666 hopeful_morse
```
Note that if the container is started with "--rm" flag, you cannot update the restart
policy for it. The `AutoRemove` and `RestartPolicy` are mutually exclusive for the
container.
|
