podman: add option --cgroup-conf

it allows to manually tweak the configuration for cgroup v2.

we will expose some of the options in future as single
options (e.g. the new memory knobs), but for now add the more generic
--cgroup-conf mechanism for maximum control on the cgroup
configuration.

OCI specs change: https://github.com/opencontainers/runtime-spec/pull/1040

Requires: https://github.com/containers/crun/pull/459

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

3 files changed, 21 insertions, 1 deletions

diff --git a/cmd/podman/common/create.go b/cmd/podman/common/create.go
index 403a1065b..d0bc8d466 100644
--- a/cmd/podman/common/create.go
+++ b/cmd/podman/common/create.go
@@ -516,5 +516,10 @@ func GetCreateFlags(cf *ContainerCLIOpts) *pflag.FlagSet {
 		"seccomp-policy", "default",
 		"Policy for selecting a seccomp profile (experimental)",
 	)
+	createFlags.StringSliceVar(
+		&cf.CgroupConf,
+		"cgroup-conf", []string{},
+		"Configure cgroup v2 (key=value)",
+	)
 	return &createFlags
 }
diff --git a/cmd/podman/common/create_opts.go b/cmd/podman/common/create_opts.go
index f9e4d7ca5..16d41988f 100644
--- a/cmd/podman/common/create_opts.go
+++ b/cmd/podman/common/create_opts.go
@@ -106,4 +106,6 @@ type ContainerCLIOpts struct {
 	SeccompPolicy     string
 
 	Net *entities.NetOptions
+
+	CgroupConf []string
 }
diff --git a/cmd/podman/common/specgen.go b/cmd/podman/common/specgen.go
index bf50bb56b..4de622916 100644
--- a/cmd/podman/common/specgen.go
+++ b/cmd/podman/common/specgen.go
@@ -450,7 +450,20 @@ func FillOutSpecGen(s *specgen.SpecGenerator, c *ContainerCLIOpts, args []string
 		s.ResourceLimits.Pids = &pids
 	}
 	s.ResourceLimits.CPU = getCPULimits(c)
-	if s.ResourceLimits.CPU == nil && s.ResourceLimits.Pids == nil && s.ResourceLimits.BlockIO == nil && s.ResourceLimits.Memory == nil {
+
+	unifieds := make(map[string]string)
+	for _, unified := range c.CgroupConf {
+		splitUnified := strings.SplitN(unified, "=", 2)
+		if len(splitUnified) < 2 {
+			return errors.Errorf("--cgroup-conf must be formatted KEY=VALUE")
+		}
+		unifieds[splitUnified[0]] = splitUnified[1]
+	}
+	if len(unifieds) > 0 {
+		s.ResourceLimits.Unified = unifieds
+	}
+
+	if s.ResourceLimits.CPU == nil && s.ResourceLimits.Pids == nil && s.ResourceLimits.BlockIO == nil && s.ResourceLimits.Memory == nil && s.ResourceLimits.Unified == nil {
 		s.ResourceLimits = nil
 	}