% DOCKER(1) Docker User Manuals % Docker Community % JUNE 2014
docker-update - Update configuration of one or more containers
docker update [--blkio-weight[=[BLKIO-WEIGHT]]] [--cpu-shares[=0]] [--cpu-period[=0]] [--cpu-quota[=0]] [--cpu-rt-period[=0]] [--cpu-rt-runtime[=0]] [--cpuset-cpus[=CPUSET-CPUS]] [--cpuset-mems[=CPUSET-MEMS]] [--help] [--kernel-memory[=KERNEL-MEMORY]] [-m|--memory[=MEMORY]] [--memory-reservation[=MEMORY-RESERVATION]] [--memory-swap[=MEMORY-SWAP]] [--restart[=""]] CONTAINER [CONTAINER...]
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.
--blkio-weight=0 Block IO weight (relative weight) accepts a weight value between 10 and 1000.
--cpu-shares=0 CPU shares (relative weight)
--cpu-period=0 Limit the CPU CFS (Completely Fair Scheduler) period
Limit the container‘s CPU usage. This flag tell the kernel to restrict the container’s CPU usage to the period you specify.
--cpu-quota=0 Limit the CPU CFS (Completely Fair Scheduler) quota
--cpu-rt-period=0 Limit the CPU real-time period in microseconds
Limit the container‘s Real Time CPU usage. This flag tell the kernel to restrict the container’s Real Time CPU usage to the period you specify.
--cpu-rt-runtime=0 Limit the CPU real-time runtime in microseconds
Limit the containers Real Time CPU usage. This flag tells the kernel to limit the amount of time in a given CPU period Real Time tasks may consume. Ex: Period of 1,000,000us and Runtime of 950,000us means that this container could consume 95% of available CPU and leave the remaining 5% to normal priority tasks.
The sum of all runtimes across containers cannot exceed the amount allotted to the parent cgroup.
--cpuset-cpus="" CPUs in which to allow execution (0-3, 0,1)
--cpuset-mems="" Memory nodes(MEMs) in which to allow execution (0-3, 0,1). Only effective on NUMA systems.
--help Print usage statement
--kernel-memory="" Kernel memory limit (format: <number>[<unit>], where unit = b, k, m or g)
Note that on kernel version older than 4.6, you can not update kernel memory on a running container if the container is started without kernel memory initialized, in this case, it can only be updated after it's stopped. The new setting takes effect when the container is started.
-m, --memory="" Memory limit (format: , where unit = b, k, m or g)
Note that the memory should be smaller than the already set swap memory limit. If you want update a memory limit bigger than the already set swap memory limit, you should update swap memory limit at the same time. If you don't set swap memory limit on docker create/run but only memory limit, the swap memory is double the memory limit.
--memory-reservation="" Memory soft limit (format: [], where unit = b, k, m or g)
--memory-swap="" Total memory limit (memory + swap)
--restart="" Restart policy to apply when a container exits (no, on-failure[:max-retry], always, unless-stopped).
The following sections illustrate ways to use this command.
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:
$ docker update --cpu-shares 512 abebf7571666
To update multiple resource configurations for multiple containers:
$ docker update --cpu-shares 512 -m 300M abebf7571666 hopeful_morse
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:
$ docker run -dit --name test --kernel-memory 50M ubuntu bash
You can update kernel memory while the container is running:
$ docker update --kernel-memory 80M test
If you started a container without kernel memory initialized:
$ 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.
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:
$ 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.