Does the Pod Affinity/Anti Affinity apply to DaemonSet pods

[krma...@gmail.com]

After the node have been selected using node affinity, can you still use pod affinity/anti affinity to further restrict daemon set pod placement ?

[David Oppenheimer]

[+kubernetes-users; kubernetes-dev to bcc]

No, and actually affinity doesn't work with DaemonSet right now either. The problem is that DaemonSet does its own scheduling and doesn't yet share all of the scheduler code. 

The only affinity-related constraint that works with DaemonSet right now is nodeSelector (a field of podSpec).

On Sun, Feb 12, 2017 at 12:26 AM, <krma...@gmail.com> wrote:

After the node have been selected using node affinity, can you still use pod affinity/anti affinity to further restrict daemon set pod placement ?

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[krma...@gmail.com]

Hi David

Thanks. You mean both nodeSelector and node affinity right. As per this doc https://kubernetes.io/docs/admin/daemons/#running-pods-on-only-some-nodes, both nodeSelector and node affinity work.

But yeah my questions was about pod affinity/anti affinity which you are saying doesnt work with DS. I am guessing it doesn't even make sense to have pod affinity/anti affinity work with Daemon Sets since then daemon set making a pod of certain kind per node definition would no longer be true ?

-Mayank

On Sunday, February 12, 2017 at 12:43:12 AM UTC-8, David Oppenheimer wrote:

[+kubernetes-users; kubernetes-dev to bcc]

No, and actually affinity doesn't work with DaemonSet right now either. The problem is that DaemonSet does its own scheduling and doesn't yet share all of the scheduler code. 

The only affinity-related constraint that works with DaemonSet right now is nodeSelector (a field of podSpec).

On Sun, Feb 12, 2017 at 12:26 AM, <krma...@gmail.com> wrote:

After the node have been selected using node affinity, can you still use pod affinity/anti affinity to further restrict daemon set pod placement ?

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[David Oppenheimer]

[moving kubernetes-dev back to bcc]

On Sun, Feb 12, 2017 at 1:11 AM, <krma...@gmail.com> wrote:

Hi David

Thanks. You mean both nodeSelector and node affinity right. As per this doc https://kubernetes.io/docs/admin/daemons/#running-pods-on-only-some-nodes, both nodeSelector and node affinity work.

I believe that documentation is wrong. More specifically, the spec.template.spec.nodeSelector part is correct, but the .spec.template.metadata.annotations part is wrong (not yet supported for DaemonSet). The predicate functions respected by DaemonSet are only the ones listed here: https://github.com/kubernetes/kubernetes/blob/4ed86f5d4649ff9e612ad945b38ce9db147daaef/plugin/pkg/scheduler/algorithm/predicates/predicates.go#L840

 

But yeah my questions was about pod affinity/anti affinity which you are saying doesnt work with DS. I am guessing it doesn't even make sense to have pod affinity/anti affinity work with Daemon Sets since then daemon set making a pod of certain kind per node definition would no longer be true ?

I guess you could use pod anti-affinity to say something like "one daemon per rack" but I agree that in general the uses are very limited.

 

-Mayank

On Sunday, February 12, 2017 at 12:43:12 AM UTC-8, David Oppenheimer wrote:

[+kubernetes-users; kubernetes-dev to bcc]

No, and actually affinity doesn't work with DaemonSet right now either. The problem is that DaemonSet does its own scheduling and doesn't yet share all of the scheduler code. 

The only affinity-related constraint that works with DaemonSet right now is nodeSelector (a field of podSpec).

On Sun, Feb 12, 2017 at 12:26 AM, <krma...@gmail.com> wrote:

After the node have been selected using node affinity, can you still use pod affinity/anti affinity to further restrict daemon set pod placement ?

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[Łukasz Oleś]

On Sunday, February 12, 2017 at 10:55:42 AM UTC+1, David Oppenheimer wrote:

[moving kubernetes-dev back to bcc]

On Sun, Feb 12, 2017 at 1:11 AM, <krma...@gmail.com> wrote:

Hi David

Thanks. You mean both nodeSelector and node affinity right. As per this doc https://kubernetes.io/docs/admin/daemons/#running-pods-on-only-some-nodes, both nodeSelector and node affinity work.

I believe that documentation is wrong. More specifically, the spec.template.spec.nodeSelector part is correct, but the .spec.template.metadata.annotations part is wrong (not yet supported for DaemonSet). The predicate functions respected by DaemonSet are only the ones listed here: https://github.com/kubernetes/kubernetes/blob/4ed86f5d4649ff9e612ad945b38ce9db147daaef/plugin/pkg/scheduler/algorithm/predicates/predicates.go#L840

GeneralPredicates checks node affinity here https://github.com/kubernetes/kubernetes/blob/4ed86f5d4649ff9e612ad945b38ce9db147daaef/plugin/pkg/scheduler/algorithm/predicates/predicates.go#L572

so DaemonSet also supports node affinity.

When I was changing DaemonSets to use GeneralPredicates I also added a unit test to check node affinity: https://github.com/kubernetes/kubernetes/blob/master/pkg/controller/daemon/daemoncontroller_test.go#L608 

Regards

[David Oppenheimer]

Ah, you're right, thanks for the correction.

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[krma...@gmail.com]

thanks all of you

On Wednesday, February 15, 2017 at 10:47:29 PM UTC-8, David Oppenheimer wrote:

Ah, you're right, thanks for the correction.

On Wed, Feb 15, 2017 at 4:43 AM, Łukasz Oleś <lukas...@gmail.com> wrote:

On Sunday, February 12, 2017 at 10:55:42 AM UTC+1, David Oppenheimer wrote:

[moving kubernetes-dev back to bcc]

On Sun, Feb 12, 2017 at 1:11 AM, <krma...@gmail.com> wrote:

Hi David

Thanks. You mean both nodeSelector and node affinity right. As per this doc https://kubernetes.io/docs/admin/daemons/#running-pods-on-only-some-nodes, both nodeSelector and node affinity work.

I believe that documentation is wrong. More specifically, the spec.template.spec.nodeSelector part is correct, but the .spec.template.metadata.annotations part is wrong (not yet supported for DaemonSet). The predicate functions respected by DaemonSet are only the ones listed here: https://github.com/kubernetes/kubernetes/blob/4ed86f5d4649ff9e612ad945b38ce9db147daaef/plugin/pkg/scheduler/algorithm/predicates/predicates.go#L840

GeneralPredicates checks node affinity here https://github.com/kubernetes/kubernetes/blob/4ed86f5d4649ff9e612ad945b38ce9db147daaef/plugin/pkg/scheduler/algorithm/predicates/predicates.go#L572

so DaemonSet also supports node affinity.

When I was changing DaemonSets to use GeneralPredicates I also added a unit test to check node affinity: https://github.com/kubernetes/kubernetes/blob/master/pkg/controller/daemon/daemoncontroller_test.go#L608 

Regards

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