Disable preStart event using validations

[kadel]

What type of PR is this?

Uncomment only one /kind line, and delete the rest.
For example, > /kind bug would simply become: /kind bug

/kind bug

What does does this PR do / why we need it:

preStart even is still not clearly defined in Devfile and it is clear how it should be defined. This will make sure that no one is using PreStart event until we have a proper implementation.

Which issue(s) this PR fixes:

Fixes #4187

PR acceptance criteria:

• Unit test

• Integration test

• Documentation

• I have read the test guidelines

How to test changes / Special notes to the reviewer:
Create a devfile with the preStart event command

events:
  preStart:
     - some-command

[dharmit]

Something's off here. When I do odo push, I see:

$ odo push        
 ✗  devfile events validation error: 
preStart type events are invalid: 
some-command does not map to a valid devfile command

I expected to see something along the lines of:

$ odo push
✗  devfile events validation error: 
"preStart" type events are not supported in odo

[dharmit]

Also, are the integration tests written with the assumption that PreStart events should work fine? 🤔

 • Failure [2.025 seconds]
odo devfile push command tests
/go/src/github.com/openshift/odo/tests/integration/devfile/cmd_devfile_push_test.go:20
  Verify devfile push works
  /go/src/github.com/openshift/odo/tests/integration/devfile/cmd_devfile_push_test.go:64
    should execute PreStart commands if present during pod startup [It]
    /go/src/github.com/openshift/odo/tests/integration/devfile/cmd_devfile_push_test.go:365
    No future change is possible.  Bailing out early after 0.071s.
      
    Running odo with args [odo push --project tmpjpmfnmc]
    Expected
        <int>: 1
    to match exit code:
        <int>: 0

[kadel]

Something's off here. When I do odo push, I see:

$ odo push        
 ✗  devfile events validation error: 
preStart type events are invalid: 
some-command does not map to a valid devfile command

This is actually correct. This is a validation that comes from devfile/library.
It means that the command that you are using in preStart even doesn't exist in commands definition. You can't reference non-existing command in events. You basically created an invalid devfile, so it fails before it gets into the odo specific validations.

[dharmit]

It means that the command that you are using in preStart even doesn't exist in commands definition. You can't reference non-existing command in events.

Second time in less than 24 hours that I misunderstood or didn't know what command means in devfile lingo. I did the same on #4381 (comment). This indicates two things to me:

1. I obviously don't understand the devfile API as well as people who designed it (you) or integrated it with odo (@mik-dass).
2. We need to make this obvious/clear in devfile documentation so that people don't fumble like I did. I'll leave this for you to take up with devfile team if it makes sense.

[dharmit]

Some rebase mess up here #4405 (commits)?

[kadel]

fixed

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kadel

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

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Needs approval from an approver in each of these files:

• pkg/devfile/OWNERS [kadel]
• tests/OWNERS [kadel]

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[dharmit]

Just a question about comment vs. deleting. But it's not a show stopper.

/lgtm

[openshift-bot]

/retest

Please review the full test history for this PR and help us cut down flakes.

[kadel]

[odo] : error while streaming command: error sending request: Post https://api.ci-op-tl8sj0lj-de358.origin-ci-int-aws.dev.rhcloud.com:6443/api/v1/namespaces/avacaawobu/pods/xwslrp-7c86484c96-wgkxk/exec?command=%2Fbin%2Fsh&command=-c&command=cd+%24%7BPROJECTS_ROOT%7D+%26%26+npm+install&container=runtime&stderr=true&stdout=true: dial tcp: lookup api.ci-op-tl8sj0lj-de358.origin-ci-int-aws.dev.rhcloud.com on 172.30.0.10:53: read udp 10.129.43.239:44972->172.30.0.10:53: i/o timeout