56f77d5ade
containers may specify these cgroup values at runtime. This will allow processes to change their priority to real-time within the container when CONFIG_RT_GROUP_SCHED is enabled in the kernel. See #22380. Also added sanity checks for the new --cpu-rt-runtime and --cpu-rt-period flags to ensure that that the kernel supports these features and that runtime is not greater than period. Daemon will support a --cpu-rt-runtime flag to initialize the parent cgroup on startup, this prevents the administrator from alotting runtime to docker after each restart. There are additional checks that could be added but maybe too far? Check parent cgroups to ensure values are <= parent, inspecting rtprio ulimit and issuing a warning. Signed-off-by: Erik St. Martin <alakriti@gmail.com>
120 lines
4.5 KiB
Markdown
120 lines
4.5 KiB
Markdown
---
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title: "update"
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description: "The update command description and usage"
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keywords: ["resources, update, dynamically"]
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---
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<!-- This file is maintained within the docker/docker Github
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repository at https://github.com/docker/docker/. Make all
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pull requests against that repo. If you see this file in
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another repository, consider it read-only there, as it will
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periodically be overwritten by the definitive file. Pull
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requests which include edits to this file in other repositories
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will be rejected.
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-->
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## update
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```markdown
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Usage: docker update [OPTIONS] CONTAINER [CONTAINER...]
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Update configuration of one or more containers
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Options:
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--blkio-weight value Block IO (relative weight), between 10 and 1000
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--cpu-period int Limit CPU CFS (Completely Fair Scheduler) period
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--cpu-quota int Limit CPU CFS (Completely Fair Scheduler) quota
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-c, --cpu-shares int CPU shares (relative weight)
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--cpu-rt-period int Limit the CPU real-time period in microseconds
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--cpu-rt-runtime int Limit the CPU real-time runtime in microseconds
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--cpuset-cpus string CPUs in which to allow execution (0-3, 0,1)
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--cpuset-mems string MEMs in which to allow execution (0-3, 0,1)
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--help Print usage
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--kernel-memory string Kernel memory limit
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-m, --memory string Memory limit
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--memory-reservation string Memory soft limit
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--memory-swap string Swap limit equal to memory plus swap: '-1' to enable unlimited swap
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--restart string Restart policy to apply when a container exits
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```
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The `docker update` command dynamically updates container configuration.
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You can use this command to prevent containers from consuming too many
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resources from their Docker host. With a single command, you can place
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limits on a single container or on many. To specify more than one container,
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provide space-separated list of container names or IDs.
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With the exception of the `--kernel-memory` option, you can specify these
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options on a running or a stopped container. On kernel version older than
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4.6, you can only update `--kernel-memory` on a stopped container or on
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a running container with kernel memory initialized.
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## Examples
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The following sections illustrate ways to use this command.
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### Update a container's cpu-shares
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To limit a container's cpu-shares to 512, first identify the container
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name or ID. You can use `docker ps` to find these values. You can also
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use the ID returned from the `docker run` command. Then, do the following:
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```bash
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$ docker update --cpu-shares 512 abebf7571666
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```
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### Update a container with cpu-shares and memory
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To update multiple resource configurations for multiple containers:
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```bash
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$ docker update --cpu-shares 512 -m 300M abebf7571666 hopeful_morse
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```
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### Update a container's kernel memory constraints
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You can update a container's kernel memory limit using the `--kernel-memory`
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option. On kernel version older than 4.6, this option can be updated on a
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running container only if the container was started with `--kernel-memory`.
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If the container was started *without* `--kernel-memory` you need to stop
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the container before updating kernel memory.
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For example, if you started a container with this command:
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```bash
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$ docker run -dit --name test --kernel-memory 50M ubuntu bash
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```
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You can update kernel memory while the container is running:
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```bash
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$ docker update --kernel-memory 80M test
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```
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If you started a container *without* kernel memory initialized:
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```bash
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$ docker run -dit --name test2 --memory 300M ubuntu bash
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```
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Update kernel memory of running container `test2` will fail. You need to stop
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the container before updating the `--kernel-memory` setting. The next time you
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start it, the container uses the new value.
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Kernel version newer than (include) 4.6 does not have this limitation, you
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can use `--kernel-memory` the same way as other options.
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### Update a container's restart policy
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You can change a container's restart policy on a running container. The new
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restart policy takes effect instantly after you run `docker update` on a
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container.
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To update restart policy for one or more containers:
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```bash
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$ docker update --restart=on-failure:3 abebf7571666 hopeful_morse
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```
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Note that if the container is started with "--rm" flag, you cannot update the restart
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policy for it. The `AutoRemove` and `RestartPolicy` are mutually exclusive for the
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container.
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