Support custom env in kubeadm ControlPlaneComponent

[chenk008]

What would you like to be added?

https://github.com/kubernetes/kubernetes/blob/7537cec567e01172c1d95b3559085d794cb2afbd/cmd/kubeadm/app/apis/kubeadm/types.go#L142-L153

For now, the ControlPlaneComponent contains ExtraArgs and ExtraVolumes. How about add custom env?

// ControlPlaneComponent holds settings common to control plane component of the cluster
type ControlPlaneComponent struct {
	// ExtraArgs is an extra set of flags to pass to the control plane component.
	// TODO: This is temporary and ideally we would like to switch all components to
	// use ComponentConfig + ConfigMaps.
	ExtraArgs map[string]string `json:"extraArgs,omitempty"`

	// ExtraVolumes is an extra set of host volumes, mounted to the control plane component.
	ExtraVolumes []HostPathMount `json:"extraVolumes,omitempty"`

        ExtraEnvs map[string]string `json:"extraEnvs,omitempty"`
}

Why is this needed?

Support custom environment variables, facilitate our control over the behavior of components and Golang runtime(e.g. GOMAXPROCS).

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[Ritikaa96]

/area kubeadm

[neolit123]

/transfer kubeadm

[neolit123]

i don't remember if we discussed this before but it seems ok to add for the next api v1beta4 or v1.

notably this functionality is possible with --patches today

[pacoxu]

I added it to the candidate list for v1beta4 in kubernetes/enhancements#970 (comment).

notably this functionality is possible with --patches today

@chenk008 have you tried the --patches workaround?

[chendave]

+1 to make this in v1beta4, the request sound reasonable to me.

If no one own this, I will take over this.

/assign

feel free to take over if anyone else want to help.

[pacoxu]

For GOMAXPROCS, there is a recent update in kubernetes/kubernetes#117016.

BTW, only some golang default env like GOGC\ GOTRACEBACK will be used for this.

• apiserver\kcm\ scheduler: env setting is not traditionally used. Only kubectl includes some env settings.
• etcd ENVs and flags are in pair: https://etcd.io/docs/v3.4/op-guide/configuration/

https://github.com/kubernetes/kubernetes/blob/af99df6a6bead927d61746dc431fc1b526af55a0/cmd/kube-apiserver/app/server.go#L158-L159

[pacoxu]

For tuning GOGC, see kubernetes/kubernetes#112408 (comment). This may be a use case.

• https://tip.golang.org/doc/gc-guide

[pacoxu]

https://tip.golang.org/doc/go1.19#runtime

• GOMEMLIMIT is a use case. We use it to tune the apiserver/KCM memory with GOGC in some clusters.

[chendave]

/close

implemented via kubernetes/kubernetes#118867

[k8s-ci-robot]

@chendave: Closing this issue.

In response to this:

/close

implemented via kubernetes/kubernetes#118867

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