Adding a limit on the size of request body the apiserver will decode for write operations

[caesarxuchao]

The first two commits are #73713.

/assign
/kind bug-fix
/sig api-machinery
/release-note-none

This doesn't require a release note because request that fails the new limit has always been invalid. This patch just make it fail early in the apiserver REST handler, instead of after hitting etcd.

kube-apiserver: a request body of a CREATE/UPDATE/PATCH/DELETE resource operation larger than 100 MB will return a 413 "request entity too large" error.

Custom apiservers built with the latest apiserver library will have the 100MB limit on the body of resource requests as well. The limit can be altered via ServerRunOptions.MaxRequestBodyBytes.

The body size limit does not apply to subresources like pods/proxy that proxy request content to another server.

[caesarxuchao]

/unassign
/assign @liggitt

[liggitt]

suggest this instead to limit to 1MB to avoid needing 200MB in memory to run this test:

	stopCh := make(chan struct{})
	defer close(stopCh)
	clientSet, _ := framework.StartTestServer(t, stopCh, framework.TestServerSetup{
		ModifyServerRunOptions: func(opts *options.ServerRunOptions) {
			opts.GenericServerRunOptions.MaxRequestBodyBytes = 1024*1024
		},
	})

[caesarxuchao]

Good point. Done.

[liggitt]

one test comment, agree on matching json patch copy size

[caesarxuchao]

@liggitt comments addressed. PTAL. Thank you.

[caesarxuchao]

/retest

[liggitt]

/retest

[caesarxuchao]

/retest

[liggitt]

/test all

[liggitt]

I think the new potential http status code is worth a release note

[liggitt]

once it has a release note and the 10->100 test fixup is done, lgtm

[caesarxuchao]

Both done. PTAL. Thanks.

[liggitt]

/lgtm
/approve

[liggitt]

updated release note to clarify the limit only applies to resource requests, not proxy subresources like pods/proxy

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: caesarxuchao, liggitt

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Needs approval from an approver in each of these files:

• cmd/kube-apiserver/OWNERS [caesarxuchao,liggitt]
• staging/src/k8s.io/apimachinery/pkg/OWNERS [caesarxuchao,liggitt]
• staging/src/k8s.io/apimachinery/pkg/apis/OWNERS [liggitt]
• staging/src/k8s.io/apiserver/OWNERS [liggitt]
• test/OWNERS [liggitt]

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