podman update is missing

[kolyshkin]

/kind feature

Description

podman update is missing

Steps to reproduce the issue:

$ podman update
$ podman container update

Describe the results you received:

$ podman update
Error: unrecognized command `podman update`
Try 'podman --help' for more information.
$ podman container update
Error: unrecognized command `podman container update`
Try 'podman container --help' for more information.

Describe the results you expected:

kir@ubuntu1910:~$ docker update   
"docker update" requires at least 1 argument.
See 'docker update --help'.

Usage:  docker update [OPTIONS] CONTAINER [CONTAINER...]

Update configuration of one or more containers
kir@ubuntu1910:~$ docker update --help

Usage:	docker update [OPTIONS] CONTAINER [CONTAINER...]

Update configuration of one or more containers

Options:
      --blkio-weight uint16        Block IO (relative weight), between 10 and 1000, or 0
                                   to disable (default 0)
      --cpu-period int             Limit CPU CFS (Completely Fair Scheduler) period
      --cpu-quota int              Limit CPU CFS (Completely Fair Scheduler) quota
      --cpu-rt-period int          Limit the CPU real-time period in microseconds
      --cpu-rt-runtime int         Limit the CPU real-time runtime in microseconds
  -c, --cpu-shares int             CPU shares (relative weight)
      --cpus decimal               Number of CPUs
      --cpuset-cpus string         CPUs in which to allow execution (0-3, 0,1)
      --cpuset-mems string         MEMs in which to allow execution (0-3, 0,1)
      --kernel-memory bytes        Kernel memory limit
  -m, --memory bytes               Memory limit
      --memory-reservation bytes   Memory soft limit
      --memory-swap bytes          Swap limit equal to memory plus swap: '-1' to enable
                                   unlimited swap
      --pids-limit int             Tune container pids limit (set -1 for unlimited)
      --restart string             Restart policy to apply when a container exits
kir@ubuntu1910:~$ 

Additional information you deem important (e.g. issue happens only occasionally):

Output of podman version:

$ podman --version
podman version 1.8.2

Package info (e.g. output of rpm -q podman or apt list podman):

$ rpm -q podman
podman-1.8.2-2.fc31.x86_64

Additional details:

• https://docs.docker.com/engine/reference/commandline/update/

[mheon]

This is deliberate. Podman containers are, by design, immutable once created.

There has been extensive discussion of a way to clone containers (podman container clone) to produce an identical copy with changes, which would act somewhat similar to update. No one's found the time to implement it yet, though.

[kolyshkin]

This is deliberate

Would be nice to have it documented/stated somewhere (say output of podman update).

Podman containers are, by design, immutable once created

The resource limits can still be changed using runc update, systemctl set property, or directly writing into cgroup files. Not implying it was a bad decision, just thinking out loud.

[mheon]

This is deliberate

Would be nice to have it documented/stated somewhere (say output of podman update).

Sure - I'd want to hide the command so it doesn't seem like update is a real command that is ready to use, but we can make it output an error to this effect.

Podman containers are, by design, immutable once created

The resource limits can still be changed using runc update, systemctl set property, or directly writing into cgroup files. Not implying it was a bad decision, just thinking out loud.

Sure - the big blocker here is actually Podman's internal storage of container configuration. Our configs (which contain an initial version of the container's OCI spec among other things) are immutable as a design decision, to make state that needs to be distributed across different Podman processes as minimal as we can. This means that, while we can certainly adjust the resources of a running container, those changes will not be saved, so our report of the container configuration in podman inspect would be wrong, and the next time the container is restarted it would not have the changes made with podman update.

[github-actions]

A friendly reminder that this issue had no activity for 30 days.

[rhatdan]

@mheon What do you want to do with this one?

[mheon]

Consolidate everything related to this in one podman container clone issue

[baude]

@mheon please do the consolidation and close this

[rhatdan]

Duplicate of #1925