agnhost: support --delay-shutdown flag for the net and netexec subcommands

[andrewsykim]

Signed-off-by: Andrew Sy Kim andrewsy@google.com

What type of PR is this?

/kind feature

What this PR does / why we need it:

This PR adds a --delay-shutdown flag to the net and netexec subcommand in the agnhost test image used in e2e tests. This will be specifically useful for tests in #108691, where we need a webserver that receives SIGTERM but continues to serve traffic.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[k8s-ci-robot]

@andrewsykim: This issue is currently awaiting triage.

If a SIG or subproject determines this is a relevant issue, they will accept it by applying the triage/accepted label and provide further guidance.

The triage/accepted label can be added by org members by writing /triage accepted in a comment.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andrewsykim

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• test/images/agnhost/OWNERS [andrewsykim]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[andrewsykim]

Contemplating this instead:

exitCh <- shutdownRequest{
    code:    0,
    timeout: time.Second,
}

But it assumes that the exit handler is already running when SIGTERM is received, which we can't guarentee

[andrewsykim]

/hold

(using --delay-shutdown from nettest might actually meet my use-case https://github.com/kubernetes/kubernetes/blob/master/test/images/agnhost/nettest/nettest.go#L91, will test this first)

[andrewsykim]

/hold cancel

After reviewing some usages of these subcommands, I think it would be useful to just extend net and netexec to have a --delay-shutdown flag similar to nettest. It would make it easier to extend current tests instead of rewriting them to use nettest

[aojea]

/lgtm

[andrewsykim]

^ sorry, ended up pushing a minor fix

[aojea]

^ sorry, ended up pushing a minor fix

is ok now?

[aojea]

/lgtm

[dims]

/assign @claudiubelu

[k8s-triage-robot]

The Kubernetes project has merge-blocking tests that are currently too flaky to consistently pass.

This bot retests PRs for certain kubernetes repos according to the following rules:

• The PR does have any do-not-merge/* labels
• The PR does not have the needs-ok-to-test label
• The PR is mergeable (does not have a needs-rebase label)
• The PR is approved (has cncf-cla: yes, lgtm, approved labels)
• The PR is failing tests required for merge

You can:

• Review the full test history for this PR
• Prevent this bot from retesting with /lgtm cancel or /hold
• Help make our tests less flaky by following our Flaky Tests Guide

/retest