feat(opentelemetry-js): infer zipkin service name from resource

[rezakrimi]

Which problem is this PR solving?

• Fixes Use resource service.name as zipkin service name #919

Short description of the changes

• Zipkin service name is set to resource 'service.name' if it's not specified in the config.

[codecov]

Codecov Report

Merging #1138 into master will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1138      +/-   ##
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+ Coverage   92.31%   92.32%   +0.01%     
==========================================
  Files         116      116              
  Lines        3397     3402       +5     
  Branches      685      689       +4     
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+ Hits         3136     3141       +5     
  Misses        261      261              

Impacted Files	Coverage Δ
...ackages/opentelemetry-exporter-zipkin/src/types.ts	100.00% <ø> (ø)
...ckages/opentelemetry-exporter-zipkin/src/zipkin.ts	98.46% <100.00%> (+0.12%)	⬆️

[mayurkale22]

Overall LGTM, added two comments.

[mayurkale22]

It would be nice if you can update the https://github.com/rezakrimi/opentelemetry-js/tree/zipkin-service-name/packages/opentelemetry-exporter-zipkin#usage and mention "serviceName is optional and can be omitted - it will be inferred from resource and in case not provided, serviceName will default to "OpenTelemetry Service"". Something like this.

[rezakrimi]

How about we mention that it's completely optional to pass the config now. So the usage section will be something like:
"Install the exporter on your application and pass the options. It's optional to pass the options. If serviceName is omitted, it will be inferred from resource and in case not provided, serviceName will default to "OpenTelemetry Service". The url is also set to http://localhost:9411/api/v2/spans by default."

[dyladan]

It's not exactly obvious how to set the service name in the resource right now, so I would focus more on the case where you do directly set the service name:

serviceName is an optional string. If omitted, the exporter will first try to get the service name from the Resource. If no service name can be detected on the Resource, a fallback name of "OpenTelemetry Service" will be used.

[mayurkale22]

I would prefer to have const for this.

[rezakrimi]

do you mean like thi?

        const defaultServiceName = String(
        spans[0].resource.labels[SERVICE_RESOURCE.NAME] ||
          'OpenTelemetry Service');

[dyladan]

No he means defining a constant somewhere like const DEFAULT_SERVICE_NAME = 'OpenTelemetry Service' then doing

String(spans[0].resource.labels[SERVICE_RESOURCE.NAME] || DEFAULT_SERVICE_NAME);

[linux-foundation-easycla]

• ✅ Mayur Kale (edcc5f9, bfc8566)

• ❌ rezakrimi The commit (6c113d7 ,e0dd7425bad29e48d51c6c4f120c9dd9909e355d ,1ce71b9b6a2c1be0baff6fc4ccf921a66f0115ec ,c0b56d37025dcfa9cb4caae7a54684c80661b657 ,42de702f41931584b0f551c4cbabd4b30152b1c0 ,ad18c2146285f1ed43c8e758459fc8c62e4d2ddd ,c7cf1181e97c9eb62863796277c414842a8b6032) is not authorized under a signed CLA. Please click here to be authorized. For further assistance with EasyCLA, please submit a support request ticket.