Enable privileged containers for apiserver and controller #57561

dims · Dec 22, 2017

What this PR does / why we need it:

In OpenStack environment, when there is no metadata service, we
look at the config drive to figure out the metadata. Since we need
to run commands like blkid, we need to ensure that api server and
kube controller are running in the privileged mode.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #47392
Fixes kubernetes/kubeadm#588

Special notes for your reviewer:

Release note:

Fix issue when using OpenStack config drive for node metadata

dims · Dec 22, 2017

/assign @luxas

dims · Dec 22, 2017

/retest

dims · Dec 22, 2017

/open

dims · Dec 22, 2017

/reopen

k8s-ci-robot · Dec 22, 2017

@dims: failed to re-open PR: state cannot be changed. There are no new commits on the dims:enable-privileged-container-for-apiserver-and-controller branch.

In response to this:

/reopen

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dims · Dec 22, 2017

/reopen

kad · Dec 22, 2017

Two questions: 1. unit tests. 2. can it be done with allowing few needed caps instead of fully privileged ?

dims · Dec 22, 2017

@kad we need CAP_SYS_ADMIN as we are mounting/unmounting file systems (similar to http://ceph.com/planet/no-more-privileged-containers-for-ceph-osds/). Any suggestions on the best way to do this?

Thanks for the quick review!

kad · Dec 22, 2017

In case of mounts, probably no suggestions from me at the moment. If CAP_SYS_ADMIN is enough, maybe that would be the best way.

dims · Dec 23, 2017

@kad so leave the current implementation as-is?

kad · Dec 27, 2017

@dims test case still will be good. so if someone will do refactoring on that code later, we will not loose it.
@liggitt what do you think about security/privileged pod for api manager and controller manager for that usage scenario ?

kad · Dec 28, 2017

lgtm, however it will be great if @liggit or somebody else from k8s security specialists comment on privileged mode.

liggitt · Dec 28, 2017

liggitt reviewed Dec 28, 2017

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liggitt · Dec 28, 2017

cmd/kubeadm/app/phases/controlplane/manifests.go

@@ -104,6 +104,16 @@ func GetStaticPodSpecs(cfg *kubeadmapi.MasterConfiguration, k8sVersion *version.
 		}, mounts.GetVolumes(kubeadmconstants.KubeScheduler)),
 	}

+	if cfg.CloudProvider == "openstack" {


Is this the first cloud provider specific things kubeadm is doing? I would like to see the plan for this going forward… this is just moving compiled-in logic up a level, when what we really want is to enable external integration of cloud provider specific modifications.

@liggitt there's at lease one precedent:

https://github.com/kubernetes/kubernetes/blob/master/cmd/kubeadm/app/phases/controlplane/manifests.go#L174

Interesting. The linked example seems like a bug… admission plugins don't depend solely on cloud provider… seems like specifying cloud provider aws with kube 1.8 would not work with that code

mikedanese · Jan 2, 2018

mikedanese reviewed Jan 2, 2018

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mikedanese · Jan 2, 2018

cmd/kubeadm/app/phases/controlplane/manifests.go

+	if cfg.CloudProvider == "openstack" {
+		True := true
+		staticPodSpecs[kubeadmconstants.KubeAPIServer].Spec.Containers[0].SecurityContext = &v1.SecurityContext{
+			Privileged: &True,


https://godoc.org/k8s.io/kubernetes/pkg/util/pointer

dims · Jan 5, 2018

/test pull-kubernetes-node-e2e

dims · Jan 10, 2018

cc @kubernetes/sig-cluster-lifecycle-pr-reviews

jamiehannaford · Jan 12, 2018

jamiehannaford reviewed Jan 12, 2018

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I'd also like if we could reduce the permission scope if possible. If it's only possible with privileged, fine with me

jamiehannaford · Jan 12, 2018

cmd/kubeadm/app/phases/controlplane/manifests.go

@@ -104,6 +105,15 @@ func GetStaticPodSpecs(cfg *kubeadmapi.MasterConfiguration, k8sVersion *version.
 		}, mounts.GetVolumes(kubeadmconstants.KubeScheduler)),
 	}

+	if cfg.CloudProvider == "openstack" {


might be worth making openstack a constant and also referencing different providers in the unit tests

@jamiehannaford i see "aws" and "gce" as well. i'll do it in another PR after this one merges

I'd rather this be more generic enablement, b/c this isn't openstack specific. This is a specific os-deployment issue.

Should i remove the if condition for openstack?

Do AWS and GCE also use the config drive for node metadata?

I don't know for sure @jamiehannaford

@dims I'd prefer an opt-in knob to enable privileged (default false), b/c again, this is very specific and not necessarily the common case.

Agree with a specific opt-in knob. I'd consider it acceptable to have documentation for that knob state that often times cloud providers need it to be set and name openstack specifically.

timothysc · Jan 17, 2018

timothysc reviewed Jan 17, 2018

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timothysc · Jan 17, 2018

cmd/kubeadm/app/phases/controlplane/manifests.go

+			Privileged: utilpointer.BoolPtr(true),
+		}
+		staticPodSpecs[kubeadmconstants.KubeControllerManager].Spec.Containers[0].SecurityContext = &v1.SecurityContext{
+			Privileged: utilpointer.BoolPtr(true),


Why does the controller manager need to talk with the meta-data service?

when the cloud provider is looking for "which node am i" info, in this specific scenario there is no openstack metadata service and the code looks in the config drive, to be able to mount the config drive it needs privs. we have a search-order (https://kubernetes.io/docs/concepts/cluster-administration/cloud-providers/) but in this case there is simply no metadata service and the only choice is the config service where it fails because the kube controller manager does not have enough super powers

It would be nice to put this down into a code comment.

@kargakis ack, if this looks ok otherwise, will happily do that in a little bit

Once the cloud-controller code is excised from the controller manager, is there any reason that we would still need this?

@timothysc correct, when we excise code that calls out to openstack cloud provider from these 2 containers we can yank the privilege flag.

When is the ETA on that excise? 1.10, 1.11? "Hand-wavy" future?

Also, would #58080 work for this use case?

@timothysc we con't currently expose --cloud-provider from kubeadm command line, so that won't help. i've updated the PR with a new field in MasterConfiguration and updated the unit test. hopefully that combination will work for everyone.

@timothysc For 1.10, i do not expect to move at least the openstack cloud provider out of tree. at best we will have an external openstack controller manager that will work for some scenarios with the in-tree one still being the primary one. 1.11 is a distinct possibility.

timothysc · Jan 17, 2018

cmd/kubeadm/app/phases/controlplane/manifests.go

@@ -104,6 +105,15 @@ func GetStaticPodSpecs(cfg *kubeadmapi.MasterConfiguration, k8sVersion *version.
 		}, mounts.GetVolumes(kubeadmconstants.KubeScheduler)),
 	}

+	if cfg.CloudProvider == "openstack" {


I'd rather this be more generic enablement, b/c this isn't openstack specific. This is a specific os-deployment issue.

dims · Jan 18, 2018

/test pull-kubernetes-unit

dims · Jan 18, 2018

/retest

timothysc · Jan 18, 2018

timothysc requested changes Jan 18, 2018

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minor nit on extraneous shufflings, then lgtm

timothysc · Jan 18, 2018

cmd/kubeadm/app/apis/kubeadm/types.go

 	NodeName             string
 	AuthorizationModes   []string

+	// Name of the cloud provider
+	CloudProvider string


The CloudProvider strings don't really need to be shuffled around, it makes it look like you're changing it for some reason.

Fixed. thanks!

timothysc · Jan 18, 2018

timothysc approved these changes Jan 18, 2018

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/lgtm
/approve

dims · Jan 18, 2018

@timothysc apologies, looks like i left one test broken, fixed it now. will ping when everything goes green.

timothysc · Jan 18, 2018

/lgtm

k8s-ci-robot · Jan 18, 2018

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dims, timothysc

Associated issue: #47392

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k8s-merge-robot · Jan 18, 2018

/test all [submit-queue is verifying that this PR is safe to merge]

k8s-merge-robot · Jan 18, 2018

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions here.

bputt · Jan 19, 2018

Will this be in a 1.9.x release?

errordeveloper · Jan 22, 2018

@bputt I think this will land in 1.10 and won't get cherry-picked into 1.9.

dims · Jan 22, 2018

@errordeveloper @bputt Ilya is correct, this will fall into the new feature category (not bug fix)

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Enable privileged containers for apiserver and controller #57561

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dims commented Dec 22, 2017 • edited

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dims commented Dec 22, 2017 •

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k8s-merge-robot merged commit `afd01c0` into kubernetes:master Jan 18, 2018
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