---
datafolder: engine-cli
datafile: docker_container_update
title: docker container update
---

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## Examples

### Update a container's 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:

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

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

To update multiple resource configurations for multiple containers:

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

### Update a container's kernel memory constraints

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.

For example, if you started a container with this command:

```bash
$ docker run -dit --name test --kernel-memory 50M ubuntu bash
```

You can update kernel memory while the container is running:

```bash
$ docker container update --kernel-memory 80M test
```

If you started a container *without* kernel memory initialized:

```bash
$ 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.

### Update a container's restart policy

You can change a container's restart policy on a running container. The new
restart policy takes effect instantly after you run `docker container update` on a
container.

To update restart policy for one or more containers:

```bash
$ docker container 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.