implement podman update

podman update allows users to change the cgroup configuration of an existing container using the already defined resource limits flags
from podman create/run. The supported flags in crun are:

this command is also now supported in the libpod api via the /libpod/containers/<CID>/update endpoint where
the resource limits are passed inthe request body and follow the OCI resource spec format

–memory
–cpus
–cpuset-cpus
–cpuset-mems
–memory-swap
–memory-reservation
–cpu-shares
–cpu-quota
–cpu-period
–blkio-weight
–cpu-rt-period
–cpu-rt-runtime
-device-read-bps
-device-write-bps
-device-read-iops
-device-write-iops
-memory-swappiness
-blkio-weight-device

resolves #15067

Signed-off-by: Charlie Doern <cdoern@redhat.com>

1 files changed, 78 insertions, 0 deletions

diff --git a/docs/source/markdown/podman-update.1.md.in b/docs/source/markdown/podman-update.1.md.in
new file mode 100644
index 000000000..2928379f3
--- /dev/null
+++ b/docs/source/markdown/podman-update.1.md.in
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+% podman-update(1)
+
+## NAME
+podman\-update - Updates the cgroup configuration of a given container
+
+## SYNOPSIS
+**podman update** [*options*] *container*
+
+**podman container update** [*options*] *container*
+
+## DESCRIPTION
+
+Updates the cgroup configuration of an already existing container. The currently supported options are a subset of the
+podman create/run resource limits options. These new options are non-persistent and only last for the current execution of the container; the configuration will be honored on its next run.
+This means that this command can only be executed on an already running container and the changes made will be erased the next time the container is stopped and restarted, this is to ensure immutability.
+This command takes one argument, a container name or ID, alongside the resource flags to modify the cgroup.
+
+## OPTIONS
+
+@@option blkio-weight
+
+@@option blkio-weight-device
+
+@@option cpu-period
+
+@@option cpu-quota
+
+@@option cpu-rt-period
+
+@@option cpu-rt-runtime
+
+@@option cpu-shares
+
+@@option cpus.container
+
+@@option cpuset-cpus
+
+@@option cpuset-mems
+
+@@option device-read-bps
+
+@@option device-read-iops
+
+@@option device-write-bps
+
+@@option device-write-iops
+
+@@option memory
+
+@@option memory-reservation
+
+@@option memory-swap
+
+@@option memory-swappiness
+
+
+## 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 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 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>