otlp: spawn thread to create blocking reqwest client

[pitoniak32]

fixes #2400

Changes

Using a new thread to create reqwest blocking client to avoid panics from async main

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[pitoniak32]

I still need to test this, just getting this up to make sure its not off track.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.4%. Comparing base (9cf7a40) to head (7b3c1c9).
Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #2431   +/-   ##
=====================================
  Coverage   79.4%   79.4%           
=====================================
  Files        122     122           
  Lines      21697   21700    +3     
=====================================
+ Hits       17240   17247    +7     
+ Misses      4457    4453    -4     

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[lalitb]

I still need to test this, just getting this up to make sure its not off track.

Thanks @pitoniak32. You can uncomment the integration test for reqwest-blocking to verify if it functions correctly with these changes? This mayn't necessarily work as there could be some issue with the integration test, I can check that separately in that case.

[cijothomas]

@pitoniak32 @lalitb
I can confirm this is working as expected. https://github.com/open-telemetry/opentelemetry-rust/compare/main...cijothomas:cijothomas/testreq-block?expand=1 is the change I tried. Obviously, had to turn off logs/traces as they are using tokio, and won't work. But once that is also addressed, this should achieve what we want - which is to use background Thread + req::Blocking by default

[lalitb]

@pitoniak32 @lalitb I can confirm this is working as expected. https://github.com/open-telemetry/opentelemetry-rust/compare/main...cijothomas:cijothomas/testreq-block?expand=1 is the change I tried. Obviously, had to turn off logs/traces as they are using tokio, and won't work. But once that is also addressed, this should achieve what we want - which is to use background Thread + req::Blocking by default

thanks @cijothomas. That makes me realize that the reqwest-blocking integration tests for logs and traces won't work till we support running batch exporter as separate dedicated thread. @pitoniak32 - please ignore my earlier comment on enabling and validating integration test. Sorry for confusion :)

[lalitb]

I can confirm these changes also work for batch log exporter modeled as separate thread in #2436.

[cijothomas]

maybe revisit this, to do an internal error log, and store None.?