Add status change event

[evidolob]

Solution/Idea

PR adds event API and new SSE(server sent event) channel status_change.

Proposed changes

PR adds event API implementation in pkg/crc/api/events/events.go Modify sync client implementation to trigger event when status is changed. Fixes in existing log events, rename constants related to SSE

Testing

1. launch demon
2. connect to status_change channel with curl -GET -i --unix-socket <path to socket>/crc-http.sock "http://localhost/events?stream=status_change"
3. start crc with curl -GET -i --unix-socket ~/.crc/crc-http.sock "http://localhost/api/start"
4. Ensure that new events appeared, like:

id:                                                                                                                            │
data: {"status":{"CrcStatus":"Starting","OpenshiftStatus":"Starting","OpenshiftVersion":"","PodmanVersion":"","DiskUse":0,"DiskSize":0,"RAMUse":0,"RAMSize":0,"Preset":"microshift"}}
event: status_change

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[evidolob]

/retest

[anjannath]

1. connect to status_change channel with curl -GET -i --unix-socket /crc-http.sock "http://localhost/events?stream=status_change"
2. start crc with crc start

the events are shown only when starting via the api curl --unix-socket ~/.crc/crc-http.sock "http://localhost/api/start" running the crc start command the events are not shown, is this expected?

[evidolob]

the events are shown only when starting via the api curl --unix-socket ~/.crc/crc-http.sock "http://localhost/api/start" running the crc start command the events are not shown, is this expected?

Yes, that is expected, as start, stop is performed on CLI side, not on daemon, at least for now.

[anjannath]

Tested locally and functionality is working as expected, LGTM. it'd be nice to have more detailed commit messages explaining the changes in each commit

[praveenkumar]

/need-rebase

[cfergeau]

I've rebased it at https://github.com/cfergeau/crc/tree/stus-change-event and added a fixup commit to fix compliation of the first commit in the series.

[cfergeau]

I'm not sure step 3. is correct in the testing instructions:

3. start crc with crc start

Don't we need to start it with the REST API for now as otherwise start won't get through the daemon?

 curl -GET -i --unix-socket ~/.crc/crc-http.sock  "http://localhost/api/start"

I was wondering if curl -GET -i --unix-socket ~/.crc/crc-http.sock "http://localhost/api/start" should also send a status event to help with syncing state if the state change behind the daemon's back?

[evidolob]

Don't we need to start it with the REST API for now as otherwise start won't get through the daemon?

Yes, you are correct, need to start with rest API.

 curl -GET -i --unix-socket ~/.crc/crc-http.sock  "http://localhost/api/start"

I was wondering if curl -GET -i --unix-socket ~/.crc/crc-http.sock "http://localhost/api/start" should also send a status event to help with syncing state if the state change behind the daemon's back?

Daemon send response only after start is finished(or error incase of any error), but calling api/start will trigger events on events?stream=status_change event channel.

[cfergeau]

Few more things I noticed during testing, if VM exists, and then I call delete, I get

id: 
data: {"status":{"CrcStatus":"Error","OpenshiftStatus":"","OpenshiftVersion":"","PodmanVersion":"","DiskUse":0,"DiskSize":0,"RAMUse":0,"RAMSize":0,"Preset":""},"error":"Cannot load 'crc' virtual machine: no such libmachine vm: crc"}
event: status_change

which does not seem correct as the VM existed before being deleted. After that, if I call again delete I don't get any notifications. If I call stop, I get first stopping and then error

Probably something that can improve with the NoVM state.

[evidolob]

Few more things I noticed during testing, if VM exists, and then I call delete, I get

id: 
data: {"status":{"CrcStatus":"Error","OpenshiftStatus":"","OpenshiftVersion":"","PodmanVersion":"","DiskUse":0,"DiskSize":0,"RAMUse":0,"RAMSize":0,"Preset":""},"error":"Cannot load 'crc' virtual machine: no such libmachine vm: crc"}
event: status_change

which does not seem correct as the VM existed before being deleted. After that, if I call again delete I don't get any notifications. If I call stop, I get first stopping and then error

That was actually bug, status was not report NoVm state, only error. (It was due to not implementing Is method for MissingHostError, so comparing error was always wrong)

Now it should work properly.

[gbraad]

What is holding back this PR?

[cfergeau]

What is holding back this PR?

Some discussion around https://github.com/crc-org/crc/pull/3903#discussion_r1476130780 would have been useful

Apart from this, as said multiple times, the comit log must be a lot more detailed about how this works:

If we don't record this knowledge now when it's more or less fresh in our minds, it will be very difficult to find this back in 6 months from now if we need it :-/

I'd say we can go with this for now, more details about the design choices, the implementation limitations, ... (this sentence is malformed though :-/ )

And https://github.com/crc-org/crc/pull/3903#discussion_r1474772073 is also still pending

[evidolob]

@cfergeau Could you look on this?

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@evidolob: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

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ci/prow/security	66237fa488efcb61403c07f015cbfd789fdc33b8	link	false	/test security

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