command: docker update
short: Update configuration of one or more containers
long: |-
  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.
usage: docker update [OPTIONS] CONTAINER [CONTAINER...]
pname: docker
plink: docker.yaml
options:
- option: blkio-weight
  default_value: "0"
  description: |
    Block IO (relative weight), between 10 and 1000, or 0 to disable (default 0)
- option: cpu-period
  default_value: "0"
  description: Limit CPU CFS (Completely Fair Scheduler) period
- option: cpu-quota
  default_value: "0"
  description: Limit CPU CFS (Completely Fair Scheduler) quota
- option: cpu-rt-period
  default_value: "0"
  description: Limit the CPU real-time period in microseconds
- option: cpu-rt-runtime
  default_value: "0"
  description: Limit the CPU real-time runtime in microseconds
- option: cpu-shares
  shorthand: c
  default_value: "0"
  description: CPU shares (relative weight)
- option: cpuset-cpus
  description: CPUs in which to allow execution (0-3, 0,1)
- option: cpuset-mems
  description: MEMs in which to allow execution (0-3, 0,1)
- option: kernel-memory
  description: Kernel memory limit
- option: memory
  shorthand: m
  description: Memory limit
- option: memory-reservation
  description: Memory soft limit
- option: memory-swap
  description: |
    Swap limit equal to memory plus swap: '-1' to enable unlimited swap
- option: restart
  description: Restart policy to apply when a container exits
examples: |-
  The following sections illustrate ways to use this command.

  ### 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 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 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 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 update` on a
  container.

  To update restart policy for one or more containers:

  ```bash
  $ 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.