Feature: OCPP server observability

[xBlaz3kx]

Proposed changes

Based on my feature request in #334, I added support for OCPP-J and Websocket server metrics.

Caution

Watch out for a breaking change: Go version updated to 1.22, because the OTel SDKs require at least 1.22.

• Metrics support via OpenTelemetry SDK
• Added OCPPJ server metrics
  • Dispatcher metrics (inflight and per client queue sizes)
  • Inbound/outbound requests
  • (WIP) ping-pong duration per client
• Added websocket metrics
  • Connected clients
  • Message rate (per client)
• Updated examples, so observabilty/metrics can be configured via env variables
• Updated docker-compose files for both TLS and non-tls examples so observability can be configured
• Added makefile commands so deploying examples is easier

Types of changes

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

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• I have read the CONTRIBUTING doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream modules

Further comments

List of things that should be noted/addressed in the future:

1. In the example, OpenTelemetry SDK exports metrics via insecure GRPC only
2. Havent added websocket request rate metric, which could be useful
3. Potential Tracing integration? Out of scope for now
4. ~~Currently, OCPPJ and websocket error metrics are not handled properly, as this is a proof of concept. ~~
5. Documentation update

[xBlaz3kx]

I'll need some help with this PR to capture metrics at points where it makes most sense and since Im not that familiar with the flows right now, Im open to suggestions.

[lorenzodonini]

Thanks a lot for the great work. I think this is a very good start, we can fine-tune more metrics down the road and/or accept requests.

I recommend waiting to improve on this until #347 is merged, since it includes some structural changes in the websocket package. Sorry about that but it's been long due.

[xBlaz3kx]

Thanks a lot for the great work. I think this is a very good start, we can fine-tune more metrics down the road and/or accept requests.

I recommend waiting to improve on this until #347 is merged, since it includes some structural changes in the websocket package. Sorry about that but it's been long due.

Hey,

no problem!

I'll wait for the PR to be merged, meanwhile I will address all the comments and add the missing error handling.

What do you think about adding tracing?

[lorenzodonini]

I'll wait for the PR to be merged, meanwhile I will address all the comments and add the missing error handling.

It's merged now, feel free to rebase. Sorry about the conflicts.

What do you think about adding tracing?

Both metric and tracing have on my TODO list for a while, so thanks for getting this started. If you wish to add tracing as well, I'd love it, but would recommend a separate PR for that.

[xBlaz3kx]

Since a lot of people have issues with the callback queue/reconnection, we should also probably add additional metrics for dispatcher and message queues.

[xBlaz3kx]

@lorenzodonini mind rereviewing? I think the PR is good enough for an initial version/PoC, definitely need to add more server metrics.