Add EventListener Logs Command

[danielhelfand]

Part of #1030

This pull request adds a command for viewing logs of EventListener pods. Follow functionality is outside the scope of this pull request. A tail option is is supported with this command to reduce the amount of most recent log lines a user will see.

Example:

# By default, get 10 most recent log lines from each pod
$ tkn el logs eventListener

[eventListener-podName]: ....

[eventListener-podName2]: ....

[eventListener-podName3]: ....

# Get 3 most recent log lines from each pod
$ tkn el logs eventListener --tail 3

# Get all logs from all pods
$ tkn el logs eventListener --tail -1

Unit testing this feature is difficult since the triggers resources for seed test data doesn't offer the ability to specify pods as part of test data. So I have added e2e testing and will look towards identifying or adding pieces needed for unit testing.

Submitter Checklist

These are the criteria that every PR should meet, please check them off as you
review them:

• Includes tests (if functionality changed/added)
• Run the code checkers with make check
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Release Notes

Adding tkn eventlistener logs command to view EventListener logs

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-cli-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/cmd/eventlistener/logs.go	Do not exist	55.8%

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-cli-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/cmd/eventlistener/logs.go	Do not exist	55.8%

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-cli-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/cmd/eventlistener/logs.go	Do not exist	55.8%

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-cli-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/cmd/eventlistener/logs.go	Do not exist	55.8%

[danielhelfand]

@dibyom Please feel free to review if you have any suggestions.

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-cli-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/cmd/eventlistener/logs.go	Do not exist	54.2%

[danielhelfand]

/test pull-tekton-cli-integration-tests

[dibyom]

Just tried this out, looks great. Thanks @danielhelfand

The only minor nitpick is that using tail -1 for all logs is something I haven't seen before. That being said, not sure if I have any better ideas there (maybe --all-logs?)

/lgtm

[danielhelfand]

The only minor nitpick is that using tail -1 for all logs is something I haven't seen before. That being said, not sure if I have any better ideas there (maybe --all-logs?)

Yeah, that's a good point on the UX of it. I was trying to base this off kubectl's implementation, which uses -1:

k logs deployment/el-github-listener-interceptor --tail -1

However, I think an explicit flag for it sounds better as you point out.

[dibyom]

Oh, I didn't realize kubectl uses -1. In that case, maybe we can just stick with that?

[danielhelfand]

So I guess kubectl actually does this:

--tail=-1: Lines of recent log file to display. Defaults to -1 with no selector, showing all log lines otherwise
10, if a selector is provided.

Maybe I can bring up in the working group this week to get some opinions. It seems kubectl by default gives all logs, but I wonder if that would be overwhelming.

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-cli-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/cmd/eventlistener/logs.go	Do not exist	54.2%

[vdemeester]

/meow
/cc @piyush-garg @chmouel

[tekton-robot]

@vdemeester:

In response to this:

/meow
/cc @piyush-garg @chmouel

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.

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: piyush-garg, vdemeester

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[pradeepitm12]

It would be nice if we refactor it like other logs command, but for now, let's get this in.
/lgtm