[Feature] Support to query relation metrics through PromQL

[wu-sheng]

Search before asking

• I had searched in the issues and found no similar feature requirement.

Description

PromQL Service doesn't support metrics of relation between services, instances or endpoints.

Use case

User could use this to build dashboards to show metrics from the lines on the topology or manually click.

Related issues

No response

Are you willing to submit a pull request to implement this on your own?

• Yes I am willing to submit a pull request on my own!

Code of Conduct

• I agree to follow this project's Code of Conduct

[wu-sheng]

@CzyerChen @weixiang1862 @yswdqz Any of you has interest in implementing this?

[theboywholived]

I am new to this repo - would like to pick this up.
Can you add some more verbose details of what is required as part of the feature?

[wu-sheng]

I am new to this repo - would like to pick this up.

Can you add some more verbose details of what is required as part of the feature?

This is not easy. Do you read most of SkyWalking codebases?

[theboywholived]

I will have to do that. I am brand-new to this repo.

[wu-sheng]

I would say, you could consider to implement this. But don't be in urgent.

This requires you to have good understanding of the whole system.

[theboywholived]

I would like to take a shot at this. I will go through the docs and readme. Is there anything else you suggest me to do? Or a similar MR for a different Query language?

[wu-sheng]

You could do as following

1. Get familiar with project, and how to run showcase. https://skywalking.apache.org/docs/skywalking-showcase/next/readme/
2. Learn MQE about the protocol and native UI for relative metrics.
3. Learn PromQL service, and workflow.
4. Try to implement this.

[theboywholived]

Okay, let me do as you recommend.

[theboywholived]

@wu-sheng I only have 16 GB RAM in my mac, I am not able to run showcase:
Release "demo" does not exist. Installing it now.
It's stuck on this step with RAM Utilization spiking up.

Is there another alternative?

[wu-sheng]

You need to run necessary components only. Don't run the default. It includes all features.

[wu-sheng]

@yswdqz told me, he will work on this from June 2nd/3th.