podman-update(1)

NAME
podman-update - Update the configuration of a given container

SYNOPSIS
podman update [options] container

podman container update [options] container

DESCRIPTION
Updates the configuration of an existing container, allowing changes to resource limits and healthchecks.

OPTIONS

  --blkio-weight=weight
Block IO relative weight. The weight is a value between 10 and 1000.

This option is not supported on cgroups V1 rootless systems.

  --blkio-weight-device=device:weight
Block IO relative device weight.

  --cpu-period=limit
Set the CPU period for the Completely Fair Scheduler (CFS), which is a duration in microseconds. Once the container's CPU quota is used up, it will not be scheduled to run until the current period ends. Defaults to 100000 microseconds.

On some systems, changing the resource limits may not be allowed for non-root users. For more details, see https://github.com/containers/podman/blob/main/troubleshooting.md#26-running-containers-with-resource-limits-fails-with-a-permissions-error

This option is not supported on cgroups V1 rootless systems.

  --cpu-quota=limit
Limit the CPU Completely Fair Scheduler (CFS) quota.

Limit the container's CPU usage. By default, containers run with the full CPU resource. The limit is a number in microseconds. If a number is provided, the container is allowed to use that much CPU time until the CPU period ends (controllable via --cpu-period).

On some systems, changing the resource limits may not be allowed for non-root users. For more details, see https://github.com/containers/podman/blob/main/troubleshooting.md#26-running-containers-with-resource-limits-fails-with-a-permissions-error

This option is not supported on cgroups V1 rootless systems.

  --cpu-rt-period=microseconds
Limit the CPU real-time period in microseconds.

Limit the container's Real Time CPU usage. This option tells the kernel to restrict the container's Real Time CPU usage to the period specified.

This option is only supported on cgroups V1 rootful systems.

  --cpu-rt-runtime=microseconds
Limit the CPU real-time runtime in microseconds.

Limit the containers Real Time CPU usage. This option 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 can 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.

This option is only supported on cgroups V1 rootful systems.

  --cpu-shares, -c=shares
CPU shares (relative weight).

By default, all containers get the same proportion of CPU cycles. This proportion can be modified by changing the container's CPU share weighting relative to the combined weight of all the running containers. Default weight is 1024.

The proportion only applies when CPU-intensive processes are running. When tasks in one container are idle, other containers can use the left-over CPU time. The actual amount of CPU time varies depending on the number of containers running on the system.

For example, consider three containers, one has a cpu-share of 1024 and two others have a cpu-share setting of 512. When processes in all three containers attempt to use 100% of CPU, the first container receives 50% of the total CPU time. If a fourth container is added with a cpu-share of 1024, the first container only gets 33% of the CPU. The remaining containers receive 16.5%, 16.5% and 33% of the CPU.

On a multi-core system, the shares of CPU time are distributed over all CPU cores. Even if a container is limited to less than 100% of CPU time, it can use 100% of each individual CPU core.

For example, consider a system with more than three cores. If the container C0 is started with --cpu-shares=512 running one process, and another container C1 with --cpu-shares=1024 running two processes, this can result in the following division of CPU shares:
PID | container | CPU | CPU share
100 | C0 | 0 | 100% of CPU0
101 | C1 | 1 | 100% of CPU1
102 | C1 | 2 | 100% of CPU2

On some systems, changing the resource limits may not be allowed for non-root users. For more details, see https://github.com/containers/podman/blob/main/troubleshooting.md#26-running-containers-with-resource-limits-fails-with-a-permissions-error

This option is not supported on cgroups V1 rootless systems.

  --cpus=number
Number of CPUs. The default is 0.0 which means no limit. This is shorthand for --cpu-period and --cpu-quota, therefore the option cannot be specified with --cpu-period or --cpu-quota.

On some systems, changing the CPU limits may not be allowed for non-root users. For more details, see https://github.com/containers/podman/blob/main/troubleshooting.md#26-running-containers-with-resource-limits-fails-with-a-permissions-error

This option is not supported on cgroups V1 rootless systems.

  --cpuset-cpus=number
CPUs in which to allow execution. Can be specified as a comma-separated list (e.g. 0,1), as a range (e.g. 0-3), or any combination thereof (e.g. 0-3,7,11-15).

On some systems, changing the resource limits may not be allowed for non-root users. For more details, see https://github.com/containers/podman/blob/main/troubleshooting.md#26-running-containers-with-resource-limits-fails-with-a-permissions-error

This option is not supported on cgroups V1 rootless systems.

  --cpuset-mems=nodes
Memory nodes (MEMs) in which to allow execution (0-3, 0,1). Only effective on NUMA systems.

If there are four memory nodes on the system (0-3), use --cpuset-mems=0,1 then processes in the container only uses memory from the first two memory nodes.

On some systems, changing the resource limits may not be allowed for non-root users. For more details, see https://github.com/containers/podman/blob/main/troubleshooting.md#26-running-containers-with-resource-limits-fails-with-a-permissions-error

This option is not supported on cgroups V1 rootless systems.

  --device-read-bps=path:rate
Limit read rate (in bytes per second) from a device (e.g. --device-read-bps=/dev/sda:1mb).

On some systems, changing the resource limits may not be allowed for non-root users. For more details, see https://github.com/containers/podman/blob/main/troubleshooting.md#26-running-containers-with-resource-limits-fails-with-a-permissions-error

This option is not supported on cgroups V1 rootless systems.

  --device-read-iops=path:rate
Limit read rate (in IO operations per second) from a device (e.g. --device-read-iops=/dev/sda:1000).

On some systems, changing the resource limits may not be allowed for non-root users. For more details, see https://github.com/containers/podman/blob/main/troubleshooting.md#26-running-containers-with-resource-limits-fails-with-a-permissions-error

This option is not supported on cgroups V1 rootless systems.

  --device-write-bps=path:rate
Limit write rate (in bytes per second) to a device (e.g. --device-write-bps=/dev/sda:1mb).

On some systems, changing the resource limits may not be allowed for non-root users. For more details, see https://github.com/containers/podman/blob/main/troubleshooting.md#26-running-containers-with-resource-limits-fails-with-a-permissions-error

This option is not supported on cgroups V1 rootless systems.

  --device-write-iops=path:rate
Limit write rate (in IO operations per second) to a device (e.g. --device-write-iops=/dev/sda:1000).

On some systems, changing the resource limits may not be allowed for non-root users. For more details, see https://github.com/containers/podman/blob/main/troubleshooting.md#26-running-containers-with-resource-limits-fails-with-a-permissions-error

This option is not supported on cgroups V1 rootless systems.

  --health-cmd="command" | '["command", arg1 , ...]'
Set or alter a healthcheck command for a container. The command is a command to be executed inside the container that determines the container health. The command is required for other healthcheck options to be applied. A value of none disables existing healthchecks.

Multiple options can be passed in the form of a JSON array; otherwise, the command is interpreted as an argument to /bin/sh -c.

  --health-interval=interval
Set an interval for the healthchecks. An interval of disable results in no automatic timer setup. The default is 30s.

Changing this setting resets the timer.

  --health-log-destination=directory_path
Set the destination of the HealthCheck log. Directory path, local or events_logger (local use container state file) (Default: local)

•   local: (default) HealthCheck logs are stored in overlay containers. (For example: $runroot/healthcheck.log)

•   directory: creates a log file named <container-ID>-healthcheck.log with HealthCheck logs in the specified directory.

•   events_logger: The log will be written with logging mechanism set by events_logger. It also saves the log to a default directory, for performance on a system with a large number of logs.

Warning: Changing this setting may cause the loss of previous logs.

  --health-max-log-count=number of stored logs
Set maximum number of attempts in the HealthCheck log file. ('0' value means an infinite number of attempts in the log file) (Default: 5 attempts)

  --health-max-log-size=size of stored logs
Set maximum length in characters of stored HealthCheck log. ("0" value means an infinite log length) (Default: 500 characters)

  --health-on-failure=action
Action to take once the container transitions to an unhealthy state. The default is none.

•   none: Take no action.

•   kill: Kill the container.

•   restart: Restart the container. Do not combine the restart action with the --restart flag. When running inside of a systemd unit, consider using the kill or stop action instead to make use of systemd's restart policy.

•   stop: Stop the container.

  --health-retries=retries
The number of retries allowed before a healthcheck is considered to be unhealthy. The default value is 3.

  --health-start-period=period
The initialization time needed for a container to bootstrap. The value can be expressed in time format like 2m3s. The default value is 0s.

Note: The health check command is executed as soon as a container is started, if the health check is successful the container's health state will be updated to healthy. However, if the health check fails, the health state will stay as starting until either the health check is successful or until the --health-start-period time is over. If the health check command fails after the --health-start-period time is over, the health state will be updated to unhealthy. The health check command is executed periodically based on the value of --health-interval.

  --health-startup-cmd="command" | '["command", arg1 , ...]'
Set a startup healthcheck command for a container. This command is executed inside the container and is used to gate the regular healthcheck. When the startup command succeeds, the regular healthcheck begins and the startup healthcheck ceases. Optionally, if the command fails for a set number of attempts, the container is restarted. A startup healthcheck can be used to ensure that containers with an extended startup period are not marked as unhealthy until they are fully started. Startup healthchecks can only be used when a regular healthcheck (from the container's image or the --health-cmd option) is also set.

  --health-startup-interval=interval
Set an interval for the startup healthcheck. An interval of disable results in no automatic timer setup. The default is 30s.

Changing this setting resets the timer, depending on the state of the container.

  --health-startup-retries=retries
The number of attempts allowed before the startup healthcheck restarts the container. If set to 0, the container is never restarted. The default is 0.

  --health-startup-success=retries
The number of successful runs required before the startup healthcheck succeeds and the regular healthcheck begins. A value of 0 means that any success begins the regular healthcheck. The default is 0.

  --health-startup-timeout=timeout
The maximum time a startup healthcheck command has to complete before it is marked as failed. The value can be expressed in a time format like 2m3s. The default value is 30s.

  --health-timeout=timeout
The maximum time allowed to complete the healthcheck before an interval is considered failed. Like start-period, the value can be expressed in a time format such as 1m22s. The default value is 30s.

  --memory, -m=number[unit]
Memory limit. A unit can be b (bytes), k (kibibytes), m (mebibytes), or g (gibibytes).

Allows the memory available to a container to be constrained. If the host supports swap memory, then the -m memory setting can be larger than physical RAM. If a limit of 0 is specified (not using -m), the container's memory is not limited. The actual limit may be rounded up to a multiple of the operating system's page size (the value is very large, that's millions of trillions).

This option is not supported on cgroups V1 rootless systems.

  --memory-reservation=number[unit]
Memory soft limit. A unit can be b (bytes), k (kibibytes), m (mebibytes), or g (gibibytes).

After setting memory reservation, when the system detects memory contention or low memory, containers are forced to restrict their consumption to their reservation. So always set the value below --memory, otherwise the hard limit takes precedence. By default, memory reservation is the same as memory limit.

This option is not supported on cgroups V1 rootless systems.

  --memory-swap=number[unit]
A limit value equal to memory plus swap. A unit can be b (bytes), k (kibibytes), m (mebibytes), or g (gibibytes).

Must be used with the -m (--memory) flag. The argument value must be larger than that of
 -m (--memory) By default, it is set to double the value of --memory.

Set number to -1 to enable unlimited swap.

This option is not supported on cgroups V1 rootless systems.

  --memory-swappiness=number
Tune a container's memory swappiness behavior. Accepts an integer between 0 and 100.

This flag is only supported on cgroups V1 rootful systems.

  --no-healthcheck
Disable any defined healthchecks for container.

  --pids-limit=limit
Tune the container's pids limit. Set to -1 to have unlimited pids for the container. The default is 2048 on systems that support "pids" cgroup controller.

  --restart=policy
Restart policy to follow when containers exit. Restart policy does not take effect if a container is stopped via the podman kill or podman stop commands.

Valid policy values are:

•   no : Do not restart containers on exit

•   never : Synonym for no; do not restart containers on exit

•   on-failure[:max_retries] : Restart containers when they exit with a non-zero exit code, retrying indefinitely or until the optional max_retries count is hit

•   always : Restart containers when they exit, regardless of status, retrying indefinitely

•   unless-stopped : Identical to always

Podman provides a systemd unit file, podman-restart.service, which restarts containers after a system reboot.

When running containers in systemd services, use the restart functionality provided by systemd. In other words, do not use this option in a container unit, instead set the Restart= systemd directive in the [Service] section. See podman-systemd.unit(5) and systemd.service(5).

EXAMPLEs
Update a container with a new cpu quota and period.
    podman update --cpus=5 myCtr

Update a container with all available options for cgroups v2.
    podman update --cpus 5 --cpuset-cpus 0 --cpu-shares 123 --cpuset-mems 0 --memory 1G --memory-swap 2G --memory-reservation 2G --blkio-weight-device /dev/zero:123 --blkio-weight 123 --device-read-bps /dev/zero:10mb --device-write-bps /dev/zero:10mb --device-read-iops /dev/zero:1000 --device-write-iops /dev/zero:1000 --pids-limit 123 ctrID

Update a container with all available options for cgroups v1.
    podman update --cpus 5 --cpuset-cpus 0 --cpu-shares 123 --cpuset-mems 0 --memory 1G --memory-swap 2G --memory-reservation 2G --memory-swappiness 50 --pids-limit 123 ctrID

SEE ALSO
podman(1)(podman.1.md), podman-create(1)(podman-create.1.md), podman-run(1)(podman-run.1.md)

HISTORY
August 2022, Originally written by Charlie Doern cdoern@redhat.com ⟨mailto:cdoern@redhat.com⟩