add node links

[lmangani]

prototype/proposal patch implementing functionality discussed in issue #20 for adding optional links (external and internal) to graph nodes. Link parameters format is similar to the details__ field:

link__{uniquename}__parameter = value

External Links

• link__id__url, link__id__title

Internal Links

• link__id__expr, link__id__uid, link__id__name, link__id__title

Format Sample

{ 
  "id": "1", 
  "title": "Service1", 
  "subTitle": "instance:#2", 
  "detail__role": "load",
  "arc__failed": 0.7, 
  "arc__passed": 0.3, 
  "mainStat": "qaz",
  "link__external__url": "http://some/service",
  "link__external__title": "custom link",
  "link__internal__expr": "rate(traces_service_graph_request_total{server=\"${__data.fields.id}\"}[$__interval])",
  "link__internal__title": "request rate",
  "link__internal__uid": "prometheus"
}

[lmangani]

@hoptical any suggestions or feedback? Thanks in advance!

[hoptical]

@lmangani Thanks for your contribution and sorry for being very late in sending my feedback. I had a terrible internet connection in my country for months and couldn't investigate further steps of this repo.

BTW, I reviewed your branch and tried to get a run and check if I can see the links or context menu in the graph layout. The context menu wasn't shown yet and the problem was there. Maybe my input JSON wasn't correct.

Would you please send a full sample of the JSON served to the plugin?