feat: Separate /model into its own module

[yurishkuro]

Jaeger repo has always been a monorepo with a single module / go.mod, because it was not meant to be used as a library. But it is often used as a library, in particular in the OpenTelemetry Collector Contrib, where many modules depend on our data model. This creates an undesired coupling, e.g. all our dependencies get pull as OTEL dependencies, sometimes causing conflicts.

In contrast, OTEL's repos are organized as multiple modules, which allows more selective dependencies.

The ask from OTEL project is to make /model as separate module (open-telemetry/opentelemetry-collector#8743 (comment)).

I don't know all that it takes to achieve that. Some trial and error will be needed. OTEL repos may serve as a blueprint.

• Do we need special handling of the model module in the main go.mod for local development?
• How does this change the build?
• How does this affect code coverage computations?
• How does this change the release / versioning process?
• How will dependency updates be handled? OTEL apparently switched from dependabot to renovatebot because of multi-module setup.
• What additional maintenance changes are needed? E.g. we have go 1.20 in go.mod, which is checked by scripts/check-go-version.sh - are there more places like that?

[AHB102]

I am new to open source, can I start with this issue ? I am familiar with Go.

[yurishkuro]

You can give it a try. You should start by outlining a proposal how this could be done, what changes are required.

[AHB102]

@yurishkuro Okay I will give it a shot, are any groups/chats which I can join ? I have quite a lot of questions, which might not be entirely related to the scope of this issue.

[yurishkuro]

https://www.jaegertracing.io/get-in-touch/

[kanha-gupta]

@yurishkuro Any entry point to begin with ? I am new to jaeger :)

[yurishkuro]

OTEL repos may serve as a blueprint.

that is the entry point (e.g. https://github.com/open-telemetry/opentelemetry-collector)

[kanha-gupta]

@yurishkuro Thanks, I will come up with a proposal soon :)

[AHB102]

@yurishkuro I shared some guidelines for the changes I plan to make. Are they good to start working on a PR?

[yurishkuro]

• I would recommend a prototype first with a fake module, not starting with /model
• I don't think this solution should require import path updates
• I don't know if any additional build or CI changes would be required (thus start with prototype)
• I don't know how the release process would be affected - do we just tag the whole repo with a new version tag as we do today and it would work?
• do we need dependabot changes to keep shared dependencies in sync across modules?

[kanha-gupta]

Hi @yurishkuro This is the prototype I have created https://github.com/kanha-gupta/jaegerModelSeperation
It contains go.mod file, go.sum file, A MakeFile and a possible readme (if needed)
Tests are successful. There is a minor protobuf dependency error which I'll resolve during finalisation.
What are your thoughts ? :)

[yurishkuro]

@kanha-gupta you moved /model into a separate repo, this is explicitly NOT what we're going after. We want to keep jaeger as the mono-repo which hosts multiple go-modules.

[RipulHandoo]

Hey @yurishkuro,

I've created a prototype for /model. Check out the demo. If it looks good, I'll replace package demo -> package model.

Let me know if I'm on the right track and if there are any issues.

[yurishkuro]

I just updated the ticket description. To make it clear - it's not rocket science to add a new go.mod file under /model, this is not what the ticket is about.

[shikharish]

@yurishkuro What is the status of this issue? Can I work on this?

[RipulHandoo]

Hey @shikharish you can work on this issue.

[yurishkuro]

I am going to close this, I don't think this is worth doing - too much work, not that much benefit.

In jaeger-v2 we may want to remove the ability to submit data in legacy formats and only accept OTLP. It will make model a fully internal module, which can eventually be phased out once the UI is upgraded to understand OTLP natively.

[yurishkuro]

Dependencies in otel/collector-contrib

$ rg -g '*.go' -g '!*_test.go' -N 'github.com\/jaegertracing' | grep -E '^\w' | sed 's/^.*"\(.*\)"$/\1/g' | grep '^github.com' | sort -u

github.com/jaegertracing/jaeger/cmd/agent/app/configmanager
github.com/jaegertracing/jaeger/cmd/agent/app/configmanager/grpc
github.com/jaegertracing/jaeger/cmd/agent/app/httpserver
github.com/jaegertracing/jaeger/cmd/agent/app/processors
github.com/jaegertracing/jaeger/cmd/agent/app/servers
github.com/jaegertracing/jaeger/cmd/agent/app/servers/thriftudp
github.com/jaegertracing/jaeger/cmd/collector/app/sampling
github.com/jaegertracing/jaeger/cmd/collector/app/sampling/samplingstrategy
github.com/jaegertracing/jaeger/model
github.com/jaegertracing/jaeger/model/converter/thrift/zipkin
github.com/jaegertracing/jaeger/pkg/cache
github.com/jaegertracing/jaeger/pkg/metrics
github.com/jaegertracing/jaeger/plugin/sampling/strategyprovider/static
github.com/jaegertracing/jaeger/plugin/storage/es/spanstore/dbmodel
github.com/jaegertracing/jaeger/proto-gen/api_v2
github.com/jaegertracing/jaeger/thrift-gen/agent
github.com/jaegertracing/jaeger/thrift-gen/baggage
github.com/jaegertracing/jaeger/thrift-gen/jaeger
github.com/jaegertracing/jaeger/thrift-gen/zipkincore