Use user URL if validation returns empty endpoint

[NathanielRN]

Which problem is this PR solving?

If a user sets the exporter URL to be something like localhost:8080, then we will run their string through the validateAndNormalizeUrl(url: string) function.

However, the new URL(url) constructor used in validateAndNormalizeUrl will return the following:

$ node
Welcome to Node.js v14.17.1.
Type ".help" for more information.
> const URL = require('url').URL;
undefined
> new URL('localhost:8080')
URL {
  href: 'localhost:8080',
  origin: 'null',
  protocol: 'localhost:',
  username: '',
  password: '',
  host: '', # Empty string!
  hostname: '',
  port: '',
  pathname: '8080',
  search: '',
  searchParams: URLSearchParams {},
  hash: ''
}
>

validateAndNormalizeUrl does not check the result of the parsing before it returns target.host which in the case above is just ''.

The correct URL would have been http://localhost:8080 which would have provided the correct target.host value:

> new URL('http://localhost:8080')
URL {
  href: 'http://localhost:8080/',
  origin: 'http://localhost:8080',
  protocol: 'http:',
  username: '',
  password: '',
  host: 'localhost:8080', # The correct value!
  hostname: 'localhost',
  port: '8080',
  pathname: '/',
  search: '',
  searchParams: URLSearchParams {},
  hash: ''
}
>

Short description of the changes

In Python we only return the .host (called .netloc) if it is not the empty string. Otherwise, we will try to access the exporter at the raw URL that the user provided.

These changes does the same: Try to validate and normalize the URL, but if the URL is the empty string, use the raw URL instead.

[codecov]

Codecov Report

Merging #2382 (62694d1) into main (fd2410c) will increase coverage by 0.80%.
The diff coverage is n/a.

❗ Current head 62694d1 differs from pull request most recent head b7bc7df. Consider uploading reports for the commit b7bc7df to get more accurate results

@@            Coverage Diff             @@
##             main    #2382      +/-   ##
==========================================
+ Coverage   92.80%   93.61%   +0.80%     
==========================================
  Files         145       55      -90     
  Lines        5226     1753    -3473     
  Branches     1071      359     -712     
==========================================
- Hits         4850     1641    -3209     
+ Misses        376      112     -264     

Impacted Files	Coverage Δ
...s/opentelemetry-core/src/platform/node/sdk-info.ts	0.00% <0.00%> (-100.00%)	⬇️
...pentelemetry-core/src/platform/node/performance.ts	0.00% <0.00%> (-100.00%)	⬇️
...emetry-api-metrics/src/platform/node/globalThis.ts	0.00% <0.00%> (-100.00%)	⬇️
...ckages/opentelemetry-exporter-zipkin/src/zipkin.ts	83.92% <0.00%> (-16.08%)	⬇️
...ackages/opentelemetry-shim-opentracing/src/shim.ts
...sync-hooks/src/AbstractAsyncHooksContextManager.ts
...elemetry-tracing/src/export/ConsoleSpanExporter.ts
...pentelemetry-core/src/platform/node/environment.ts
...ges/opentelemetry-metrics/src/SumObserverMetric.ts
...elemetry-exporter-zipkin/src/platform/node/util.ts
... and 84 more

[NathanielRN]

Just noticed that #2322 resolves a similar issue. Will update this PR after looking at it more closely.

[NathanielRN]

Never mind, I think #2322 solves my issue 🙂