docs: add ioredis example

[naseemkullah]

Which problem is this PR solving?

• Adds an example for ioredis

Short description of the changes

• Adds an example for ioredis

[codecov-io]

Codecov Report

Merging #665 into master will decrease coverage by 1.6%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master    #665      +/-   ##
=========================================
- Coverage   92.61%     91%   -1.61%     
=========================================
  Files         228     225       -3     
  Lines       10248   10396     +148     
  Branches      934     956      +22     
=========================================
- Hits         9491    9461      -30     
- Misses        757     935     +178

Impacted Files	Coverage Δ
packages/opentelemetry-core/test/utils/url.test.ts	50% <0%> (-50%)	⬇️
...pentelemetry-core/test/internal/validators.test.ts	50% <0%> (-50%)	⬇️
...elemetry-core/test/trace/spancontext-utils.test.ts	55.55% <0%> (-44.45%)	⬇️
...lemetry-core/test/trace/ProbabilitySampler.test.ts	56.52% <0%> (-43.48%)	⬇️
...s/opentelemetry-core/test/trace/NoopTracer.test.ts	60% <0%> (-40%)	⬇️
...s/opentelemetry-core/test/context/B3Format.test.ts	63.39% <0%> (-36.61%)	⬇️
...ges/opentelemetry-core/test/trace/NoopSpan.test.ts	63.63% <0%> (-36.37%)	⬇️
...s/opentelemetry-core/test/trace/tracestate.test.ts	65.06% <0%> (-34.94%)	⬇️
...ntelemetry-core/test/trace/NoRecordingSpan.test.ts	71.42% <0%> (-28.58%)	⬇️
...ackages/opentelemetry-core/src/platform/node/id.ts	71.42% <0%> (-28.58%)	⬇️
... and 44 more

[dyladan]

Nothing looks wrong to me here so I'm going to give it an approval, but in the future I think we should make the examples as simple as possible. This one has a client and server aspect to it and a lot of code not dealing specifically with ioredis which can make the ioredis code feel a little lost. I realize the other examples do this too, but there are a lot of examples now with client/server and I think we should simplify them.

[OlivierAlbertini]

express and axios should be removed

[naseemkullah]

Nothing looks wrong to me here so I'm going to give it an approval, but in the future I think we should make the examples as simple as possible. This one has a client and server aspect to it and a lot of code not dealing specifically with ioredis which can make the ioredis code feel a little lost. I realize the other examples do this too, but there are a lot of examples now with client/server and I think we should simplify them.

I agree. This example is based off of other examples in the repo as you mention but I will adjust it according to your suggestion.

[naseemkullah]

Let's hold off as there is an inherent issue with the ioredis plugin in general as per #668

[naseemkullah]

The example has been simplified.

[dyladan]

Adding the hold label since we're waiting on another issue

[dyladan]

@naseemkullah now that the bug is fixed, is this ready?

[naseemkullah]

@naseemkullah now that the bug is fixed, is this ready?

yep! thanks.

[naseemkullah]

@dyladan should this now be module.exports = opentelemetry.getTracerRegistry(); ?
Should the file be renamed to tracer-registry.js in this case?

As a side note I find this whole tracer registry/factory thing to be confusing for the end user. I wish the focus was that libs just not have broken implementations of tracers.

[dyladan]

Yes that means it becomes tracer registry.

"just don't have bugs" is not a feasible answer to the problem unfortunately.

Fortunately, most end users won't have to worry about it too much, just library developers. The only change for most end users is the name of the global object they need to create. Most users will never call any methods on the tracer registry manually.

[naseemkullah]

Thanks for explaining.

[naseemkullah]

@dyladan should this now be module.exports = opentelemetry.getTracerRegistry(); ?
Should the file be renamed to tracer-registry.js in this case?

@dyladan I had not yet made the above fix. Do you want a follow up PR for this?

[dyladan]

You can make a follow up PR to handle it, but you're not actually using the exported value in your index, so it shouldn't matter.