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[WIP] Adding livez and readyz endpoints #548

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[WIP] Adding livez and readyz endpoints #548

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bytetwin
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@bytetwin bytetwin commented Jun 24, 2020 •
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What this PR does / why we need it:
Exposing

  1. livez endpoint - Metrics Server is alive if it is able to respond to HTTP request and there was a scrape job that finished (no success needed) within last period
  2. 'readyz' endpoint - Metrics Server is ready if it is able to respond to HTTP request, was able to access apiserver and last scrape job has succeeded for at least one node
  3. Probe config in deployment file

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 #542

@k8s-ci-robot k8s-ci-robot added do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. labels Jun 24, 2020
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Hi @hanumanthan. Thanks for your PR.

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@k8s-ci-robot k8s-ci-robot added the needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. label Jun 24, 2020
@k8s-ci-robot k8s-ci-robot added the size/L Denotes a PR that changes 100-499 lines, ignoring generated files. label Jun 24, 2020
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/assign @serathius

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where and storage has metrics for atleast one node came from?

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where and storage has metrics for atleast one node came from?

Liveness of container should not depend on external services (assuming that container can recover from network problems). Apiserver being down should not cause a MS restart (it behaves like that currently and this is not correct). Here proposed definition requires at least one successfully scraped node, meaning that it should not fail on Apiseriver down if we discovered at least one node.

For successfully scraped node, I am checking if internal storage has at least one node.

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serathius commented Jun 24, 2020 •
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at least one successfully scraped node != internal storage has at least one node.

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Please implement probes as described on design or propose to change it

Metrics Server is alive if it is able to respond to HTTP request and there was a scrape job that finished (no success needed) within last period
Metrics Server is ready if it is able to respond to HTTP request, was able to access apiserver and last scrape job has succeeded for at least one node

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@serathius Updated the PR. Please have a look

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[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: hanumanthan
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serathius
serathius reviewed Jul 5, 2020
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pkg/storage/storage.go
@@ -116,6 +117,10 @@ func (p *Storage) GetContainerMetrics(pods ...apitypes.NamespacedName) ([]api.Ti
}

func (p *Storage) Store(batch *MetricsBatch) error {
// No node has been scraped. Return so the previous updated cache remains intact
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@serathius serathius Jul 5, 2020 •
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I'm not sure about leaving not clearing cache. HPA and VPA are prepared to handle missing data, but returning stale data could lead to bad scaping decisions.

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Looks good, just need to figure out how to check apiserver connection. I will try to look into that

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@hanumanthan: PR needs rebase.

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@k8s-ci-robot k8s-ci-robot added the needs-rebase Indicates a PR cannot be merged because it has merge conflicts with HEAD. label Aug 4, 2020
@serathius serathius mentioned this pull request Sep 23, 2020
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Closing as @hanumanthan confirmed that they will not be able to finish work on PR (confirmation #542 (comment))
I will continue work on it in #592

@serathius serathius closed this Sep 23, 2020
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Implement kubernetes probes
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