Pull Request #1176 broke backward compatibility

[sperlingxx]

/kind bug

What steps did you take and what happened:
The refactoring of metric schema in this commit made the schema of TrialStatus.Observation incompatible with legacy trials (because float metric value in legacy trials can't be parsed as string value). So, the trial controller will crash after updating to latest master.

What did you expect to happen:
In my opinion, we had better to fix this problem. Otherwise, users have to evict all existing trials before updating katib. Maybe we can keep the original float64 field value, and add another string field like non_numeric_value (which stores non-numeric metric value). If fieldnon_numeric_value is set, then take value of this field as metric value; If not, take value of original field value.

What do you think ? @andreyvelich @gaocegege

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[gaocegege]

How about creating a new version v1beta1 @johnugeorge @andreyvelich

[andreyvelich]

Good point @sperlingxx.

I am not sure that we should duplicate parameters in API. That can increase API complexity.
Currently, we don't have stable Katib API and versions update mechanism, Katib is in alpha version.
I think, if users don't want to use Kubeflow 1.0 version with 0.8 Katib version and use latest Katib release, they should restart running Experiment or they can have more errors.

I am ok with reverting this commit from upstream now and push it to the new version (v1beta1).

What do you think @johnugeorge @gaocegege ?

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[gaocegege]

SGTM

[sperlingxx]

@andreyvelich The approach ( "reverting this commit from upstream now and push it to the new version (v1beta1)" ) looks great. And when we setup v1beta1?

[andreyvelich]

@johnugeorge @gaocegege Do we want to try to resolve some p0/p1 tasks before new release?

[gaocegege]

I think we can do it now and start developing on v1beta1. WDYT @johnugeorge

[johnugeorge]

Agree. @gaocegege Lets work on v1beta1 api and get all new api changes in v1beta1