<!--- Provide a general summary of your changes in the Title above --->
<!--- Why is this change required? What problem does it solve? -->
Introduces the CLI command flag `--disable-full-test`
By default, it doesn't alter the current behavior of the tests performed by the admission controller.
With or Without the flag, a full checkOverlap is actioned, without any alteration
and the object `pcfg` is created with the whole set of ingreses.
If the flag is set to true, it does manipulate the size of `pcfg` up to the content of $this single ingress.
This is achieved by overriding pcfg content by just the last slice that got recently appended to the object `ings`
```
if n.cfg.DisableFullValidationTest {
_, _, pcfg = n.getConfiguration(ings[len(ings)-1:])
}
```
The following steps of generateTemplate and testTemplate are significally reduced to a signle scenario
```
content, err := n.generateTemplate(cfg, *pcfg)
...
err = n.testTemplate(content)
```
This flag doesn't avoid the proper testing of collisions, neither bad syntaxis within the rendered
configuration of the ingress.
But it does eliminate a scenario, which I wasn't able to produce, where by for some reason even proper rendering
and valid values, without collisions of host/path may end into an invalid nginx.conf
The reasoning for this Feature is:
- Test duration increases by the number of ingresses in the cluster.
- File size grows to very important numbers 150-200Mb on clusters with just 2000~ ingresses.
- Tests in that scenario, takes approximately 20s using the last 0.48.1 improvements
- Produces a considerable memory consumption, as well as CPU, compute, that affects directly the containers
that serve traffic.
Since the flag is trully optional, and by default is disabled I fell as a good thing to have that can definitively
help on large-scale scenarios that still want to have a reasonable set of tests in place at a lower cost.
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- [ ] Bug fix (non-breaking change which fixes an issue)
- [X ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to change)
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<!--- see how your change affects other areas of the code, etc. -->
Tested with the build kit the following scenarios on a cluster with 1000~ ingresses:
- With Flag Disabled or Flag, not present (current status as per 0.48.1)
collision scenario (wrong snippet content):
`kubectl apply -f ../collision-syntax.yaml 0.18s user 0.05s system 3% cpu 6.639 total`
collisions scenario (duplicated host):
`kubectl apply -f ../collision-host.yaml 0.17s user 0.05s system 3% cpu 6.245 total`
create/update:
`kubectl apply -f ing-215.yaml 0.16s user 0.05s system 3% cpu 5.845 total`
- With Flag Enabled (true):
collision scenario (wrong snippet content):
`kubectl apply -f ../collision.yaml 0.18s user 0.02s system 57% cpu 0.347 total`
collision scenario (duplicated host):
`kubectl apply -f ../collision.yaml 0.21s user 0.06s system 85% cpu 0.318 total`
create/update:
`kubectl apply -f ing-973.yaml 0.17s user 0.03s system 72% cpu 0.271 total`
As part of the test, I did verified that the created nginx for the test was of a smaller size, and that it didnt affect negatively the final nginx.conf (of a much larger side) where this was merged by the next steps in place after the validation. I couldn't observe any other change in the behaviour and so far the routine looks simple and non harmful.
<!--- Go over all the following points, and put an `x` in all the boxes that apply. -->
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- [x] My change requires a change to the documentation.
- [x] I have updated the documentation accordingly.
- [x] I've read the [CONTRIBUTION](https://github.com/kubernetes/ingress-nginx/blob/main/CONTRIBUTING.md) guide
- [ ] I have added tests to cover my changes.
- [ ] All new and existing tests passed.
For the test part, I would need to understand the placement and test case that this would require, I wasn't able to see an existing scenario for this
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