Update UI to use new endpoint to get a list of operations

[guo0693]

Requirement - what kind of business use case are you trying to solve?

Relates to jaegertracing/jaeger#1920

Problem - what in Jaeger blocks you from solving the requirement?

Currently UI is using the old endpoint to get a list of operation names:

api/services/%s/operations

With the change in #1920, the new endpoint:

api/operations?service=%s&spanKind=%s

can return a list of operation names with spanKind.

Proposal - what do you suggest to solve the problem or improve the existing situation?

Please use the new endpoint to retrieve the list of operation names together with spanKind. And also render & order the dropdown list with special tags, e.g. (server) before the operation name.

Any open questions to address

How do we define the order of dropdown list?

[guo0693]

@everett980 @yurishkuro

[everett980]

@guo0693 is this change for the search view as well as the DDG operation drop down?
The DDG is already updated, but I don't think search view should only show server operations. If I'm a service owner I may want to see traces that hit a particular client span of mine (such as if I wrapped deprecated code in a client span).

[guo0693]

@yurishkuro proposed the UI enhancement of showing (spanKind) in the dropdown. I don't think we want to filter out the operations in the search page, we probably just need to show the prefix. We do need to figure out how to order the operations though.

The main point of this issue is to use the new endpoint so that backend can remove the legacy one in future release.

[everett980]

Oh so this is to use the new endpoint without any query param filter?

[yurishkuro]

There are two asks. One is to switch to the new endpoint that does not encode service name in the path. It returns the result a bit differently, with span kinds. Second ask is to display span kinds in the Services drop down, and order services by (kind, name), but with kind=server coming above kind=client and others (in other words, “endpoints” first).