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Add HPA test for FailedGetExternalMetric
**What this PR does / why we need it**:
Add a HPA test for missing external metrics.
**Release note**:
```
NONE
```
Similar to the change we made for `GetObjectMetricReplicas` in the
previous commit. Ensure that `GetExternalMetricReplicas` does not
include unready pods when its determining how many replica it desires.
Including unready pods can lead to over-scaling.
We did not change the behavior of `GetExternalPerPodMetricReplicas`, as
it is slightly less clear what is the desired behavior. We did make some
small naming refactorings to this method, which will make it easier to
ignore unready pods if we decide we want to.
Previously, when `GetObjectMetricReplicas` calculated the desired
replica count, it multiplied the usage ratio by the current number of replicas.
This method caused over-scaling when there were pods that were not ready
for a long period of time. For example, if there were pods A, B, and C,
and only pod A was ready, and the usage ratio was 500%, we would
previously specify 15 pods as the desired replicas (even though really
only one pod was handling the load).
After this change, we now multiple the usage
ratio by the number of ready pods for `GetObjectMetricReplicas`.
In the example above, we'd only desire 5 replica pods.
This change gives `GetObjectMetricReplicas` the same behavior as the
other replica calculator methods. Only `GetExternalMetricReplicas` and
`GetExternalPerPodMetricRepliacs` still allow unready pods to impact the
number of desired replicas. I will fix this issue in the following
commit.
Currently, when performing a scale up, any failed pods (which can be present for example in case of evictions performed by kubelet) will be treated as unready. Unready pods are treated as if they had 0% utilization which will slow down or even block scale up.
After this change, failed pods are ignored in all calculations. This way they do not influence neither scale up nor scale down replica calculations.
With the introduction of the RESTMetrics client, there are two ways to
fetch metrics for auto-scaling. However, they previously shared error
messages. This could be misleading. Make the error message more clearly
show which method is in use.
There have been a couple of recent bugs in the "normalizing" part of the
`reconcileAutoscaler` method. This part of the code base is responsible
for, among other things, taking the suggested desired replicas based on
the metrics, ensuring it conforms to certain conditions, and updating it
if it does not. Isolate the part that converts the desired replicas
based on a given set of rules into its own function.
We are refactoring this part of the code base to make the logic simpler
and to make it easier to write unit tests.
Automatic merge from submit-queue (batch tested with PRs 53743, 53564). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Polymorphic Scale Client
This PR introduces a polymorphic scale client based on discovery information that's able to scale scalable resources in arbitrary group-versions, as long as they present the scale subresource in their discovery information.
Currently, it supports `extensions/v1beta1.Scale` and `autoscaling/v1.Scale`, but supporting other versions of scale if/when we produce them should be fairly trivial.
It also updates the HPA to use this client, meaning the HPA will now work on any scalable resource, not just things in the `extensions/v1beta1` API group.
**Release note**:
```release-note
Introduces a polymorphic scale client, allowing HorizontalPodAutoscalers to properly function on scalable resources in any API group.
```
Unblocks #29698
Unblocks #38756
Unblocks #49504Fixes#38810
This updates the HPA controller to use the polymorphic scale client from
client-go. This should enable HPAs to work with arbitrary scalable
resources, instead of just those in the extensions API group (meaning we
can deprecate the copy of ReplicationController in extensions/v1beta1).
It also means that the HPA controller now pays attention to the
APIVersion field in `scaleTargetRef` (more specifically, the group part
of it).
Note that currently, discovery information on which resources are
available where is only fetched once (the first time that it's
requested). In the future, we may want a refreshing discovery REST
mapper.
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pkg/api: extract Scheme/Registry/Codecs into pkg/api/legacyscheme
This serves as
- a preparation for the pkg/api->pkg/apis/core move
- and makes the dependency to the scheme explicit when vizualizing
left depenncies.
The later helps with our our efforts to split up the monolithic repo
into self-contained sub-repos, e.g. for kubectl, controller-manager
and kube-apiserver in the future.
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fix typos: remove duplicated word in comments
**What this PR does / why we need it**: Remove the duplicated word `the` in comments
**Which issue this PR fixes** : fixes #
**Special notes for your reviewer**:
```release-note
NONE
```
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Make HPA tolerance a flag
**What this PR does / why we need it**:
Make HPA tolerance configurable as a flag. This change allows us to use
different tolerance values in production/testing.
**Which issue this PR fixes**:
Fixes#18155
**Release note:**
```release-note
Control HPA tolerance through the `horizontal-pod-autoscaler-tolerance` flag.
```
Signed-off-by: mattjmcnaughton <mattjmcnaughton@gmail.com>
Fix#53670
Fix a bug where `desiredReplicas` could be greater than `maxReplicas`
if the original value for `desiredReplicas > scaleUpLimit` and
`scaleUpLimit > maxReplicas`. Previously, when that happened, we would
scale up to `scaleUpLimit`, and then in the next auto-scaling run, scale
down to `maxReplicas`. Address this issue and introduce a regression
test.
Previously
`pkg.controller.podautoscaler.UnsafeConvertToVersion` was
exported. However, it was never used outside of the `podautoscaler`
package. Make it private to prevent confusion.
Additionally, move the two private functions in `horizontal.go` to be
with the other private functions at the bottom of the file - imho its
more readable than having them directly at the top of the file, before
the public type and function definitions.
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Improve `horizontal.go` documentation
**What this PR does / why we need it**:
Resolve the remaining `golint` errors in the
`pkg/controller/podautoscaler` package by improving the documentation
in `horizontal.go`. Now all public methods have comments.
**Special notes for your reviewer**:
Re discussions in [this pr](https://github.com/kubernetes/kubernetes/pull/52238).
**Release note**:
```release-note
NONE
```
Fix#18155
Make HPA tolerance configurable as a flag. This change allows us to use
different tolerance values in production/testing.
Signed-off-by: mattjmcnaughton <mattjmcnaughton@gmail.com>
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Fix golint errors in `pkg/controller/podautoscaler`
**What this PR does / why we need it**:
Address `golint` errors in `pkg/controller/podautoscaler`. Note,
I did not address issues around exported types/functions missing
comments, because I'm not sure what the convention within the k8s project is.
```release-note
NONE
```
Signed-off-by: mattjmcnaughton <mattjmcnaughton@gmail.com>
Resolve the remaining `golint` errors in the
`pkg/controller/podautoscaler` package by improving the documentation
in `horizontal.go`. Now all public methods have comments.
Fix#49256
When `ScalingLimited = true` for the `hpa`, there is an accompanying
status message, describing why scaling is limited. Previously if the desired
replica count was 0, and spec.minReplicas > 0, the status message
indicated "the desired replica count was less than the min replica
count". This was particularly confusing when `spec.MinReplicas = 1`. If
there was no `spec.minReplicas`, then the status message indicated "the
desired replica count was zero" which is more informative.
Update the calculation of status message so that if the desired replica
count is 0, we always display the clearer "the desired replica count was
zero" status message, even if spec.minReplicas > 0.
Signed-off-by: mattjmcnaughton <mattjmcnaughton@gmail.com>
Address `golint` errors in `pkg/controller/podautoscaler`. Note,
I did not address issues around exported types/functions missing
comments, because I'm not sure what the convention within the k8s project is.
Signed-off-by: mattjmcnaughton <mattjmcnaughton@gmail.com>
Automatic merge from submit-queue (batch tested with PRs 51956, 50708)
Move autoscaling/v2 from alpha1 to beta1
This graduates autoscaling/v2alpha1 to autoscaling/v2beta1. The move is more-or-less just a straightforward rename.
Part of kubernetes/features#117
```release-note
v2 of the autoscaling API group, including improvements to the HorizontalPodAutoscaler, has moved from alpha1 to beta1.
```
Guoliang Wang