podman info - print available cgroup controllers

[aojea]

Opening a new issue with from:

Originally posted by @afbjorklund in #10289 (comment)

If i understand correctly, they had some different original requirements anyway:

		// Unlike `docker info`, `podman info` does not print available cgroup controllers.
		// So we parse "cgroup.subtree_control" file by ourselves.

So maybe they were more interested in cgroupVersion, and some new fields ?

	MemoryLimit     bool     `json:"MemoryLimit"`
	PidsLimit       bool     `json:"PidsLimit"`
	CPUShares       bool     `json:"CPUShares"`

kubernetes-sigs/kind#2233

[afbjorklund]

The complete list is available at github.com/docker/docker/pkg/sysinfo

    v.MemoryLimit = sysInfo.MemoryLimit
    v.SwapLimit = sysInfo.SwapLimit
    v.KernelMemory = sysInfo.KernelMemory
    v.KernelMemoryTCP = sysInfo.KernelMemoryTCP
    v.OomKillDisable = sysInfo.OomKillDisable
    v.CPUCfsPeriod = sysInfo.CPUCfsPeriod
    v.CPUCfsQuota = sysInfo.CPUCfsQuota
    v.CPUShares = sysInfo.CPUShares
    v.CPUSet = sysInfo.Cpuset
    v.PidsLimit = sysInfo.PidsLimit

https://github.com/moby/moby/tree/master/pkg/sysinfo

[rhatdan]

Care to open a PR to fix?

[rhatdan]

Do you want podman info to report all of this information?

[afbjorklund]

Do you want podman info to report all of this information?

The request from kind was for three new fields. Maybe add swap* too ?

// dockerInfo corresponds to `docker info --format '{{json .}}'`
type dockerInfo struct {
        CgroupDriver    string   `json:"CgroupDriver"`  // "systemd", "cgroupfs", "none"
        CgroupVersion   string   `json:"CgroupVersion"` // e.g. "2"
        MemoryLimit     bool     `json:"MemoryLimit"`
        PidsLimit       bool     `json:"PidsLimit"`
        CPUShares       bool     `json:"CPUShares"`
        SecurityOptions []string `json:"SecurityOptions"`
}

It is mostly used for producing warnings, when running rootless / cgroups v2:

        if info.Rootless {
                if !info.Cgroup2 {
                        return errors.New("running kind with rootless provider requires cgroup v2, see https://kind.sigs.k8s.io/docs/user/rootless/")
                }
                if !info.SupportsMemoryLimit || !info.SupportsPidsLimit || !info.SupportsCPUShares {
                        return errors.New("running kind with rootless provider requires setting systemd property \"Delegate=yes\", see https://kind.sigs.k8s.io/docs/user/rootless/")
                }
        }

* mostly because it defaults to not being enabled, when running on Ubuntu

WARNING: No swap limit support

---

The current code was trying to parse /sys itself, which is why it failed when running with podman-remote.

https://github.com/kubernetes-sigs/kind/blob/main/pkg/cluster/internal/providers/docker/provider.go#L308

https://github.com/kubernetes-sigs/kind/blob/main/pkg/cluster/internal/providers/podman/provider.go#L367

If the three fields were available in the info JSON, it would not have to resort to such desperate measures.