Introduce confighttp.HTTPTransportSettings

[urso]

Description:

The change introduces a HTTPTransportSettings struct, that is only used to configure an http.Client and http.Transport. The HTTPClientSettings structs embeds the HTTPTransportSettings, only
adding the endpoint setting.

The ToClient method is moved to HTTPTransportSettings, as the new type retains all fields that have been used by (*HTTPClientSettings).ToClient in the past.

Separating transport settings from the endpoint setting encourages reuse for exporters that allow users to configure multiple endpoints. For example when working on the Elasticsearch exporter (PR) a separate struct for HTTP settings is introduced, because the endpoint setting does not fit the exporter. Yet all other settings are copied. Still, having a common struct to share settings improves consistency among different exporters (and other settings), reducing the chance of features diverging in their capabilities.

Link to tracking Issue: None

Testing: The existing tests have been adapted.

Documentation: Add response_header_timeout to confighttp/README.md

[codecov]

Codecov Report

Merging #2470 (3df3f2c) into main (9de6dd7) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #2470   +/-   ##
=======================================
  Coverage   91.76%   91.77%           
=======================================
  Files         265      265           
  Lines       15111    15119    +8     
=======================================
+ Hits        13867    13875    +8     
  Misses        866      866           
  Partials      378      378           

Impacted Files	Coverage Δ
config/confighttp/confighttp.go	100.00% <100.00%> (ø)
exporter/otlphttpexporter/factory.go	92.10% <100.00%> (+0.21%)	⬆️
exporter/prometheusremotewriteexporter/factory.go	100.00% <100.00%> (ø)
exporter/zipkinexporter/factory.go	100.00% <100.00%> (ø)

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[urso]

The tests fail on open-telemetry-contrib, which is somewhat to be expected as the type of HTTPClientSettings has changed. For example:

go test ./... in ./exporter/alibabacloudlogserviceexporter
ok  	github.com/open-telemetry/opentelemetry-collector-contrib/exporter/alibabacloudlogserviceexporter	4.016s
go test ./... in ./exporter/awsemfexporter
go: downloading github.com/aws/aws-sdk-go v1.37.6
go: downloading go.opentelemetry.io/otel v0.15.0
ok  	github.com/open-telemetry/opentelemetry-collector-contrib/exporter/awsemfexporter	14.885s
ok  	github.com/open-telemetry/opentelemetry-collector-contrib/exporter/awsemfexporter/handler	0.006s
ok  	github.com/open-telemetry/opentelemetry-collector-contrib/exporter/awsemfexporter/mapwithexpiry	1.015s
go test ./... in ./exporter/awskinesisexporter
ok  	github.com/open-telemetry/opentelemetry-collector-contrib/exporter/awskinesisexporter	0.013s
go test ./... in ./exporter/awsprometheusremotewriteexporter
# github.com/open-telemetry/opentelemetry-collector-contrib/exporter/awsprometheusremotewriteexporter [github.com/open-telemetry/opentelemetry-collector-contrib/exporter/awsprometheusremotewriteexporter.test]
./auth_test.go:50:3: cannot use promoted field HTTPTransportSettings.TLSSetting in struct literal of type confighttp.HTTPClientSettings
./auth_test.go:51:3: cannot use promoted field HTTPTransportSettings.ReadBufferSize in struct literal of type confighttp.HTTPClientSettings
./auth_test.go:52:3: cannot use promoted field HTTPTransportSettings.WriteBufferSize in struct literal of type confighttp.HTTPClientSettings
./auth_test.go:53:3: cannot use promoted field HTTPTransportSettings.Timeout in struct literal of type confighttp.HTTPClientSettings
./auth_test.go:54:3: cannot use promoted field HTTPTransportSettings.CustomRoundTripper in struct literal of type confighttp.HTTPClientSettings
./config_test.go:78:5: cannot use promoted field HTTPTransportSettings.TLSSetting in struct literal of type confighttp.HTTPClientSettings
./config_test.go:84:5: cannot use promoted field HTTPTransportSettings.ReadBufferSize in struct literal of type confighttp.HTTPClientSettings
./config_test.go:86:5: cannot use promoted field HTTPTransportSettings.WriteBufferSize in struct literal of type confighttp.HTTPClientSettings
./config_test.go:88:5: cannot use promoted field HTTPTransportSettings.Timeout in struct literal of type confighttp.HTTPClientSettings
./config_test.go:90:5: cannot use promoted field HTTPTransportSettings.Headers in struct literal of type confighttp.HTTPClientSettings
./config_test.go:90:5: too many errors
FAIL	github.com/open-telemetry/opentelemetry-collector-contrib/exporter/awsprometheusremotewriteexporter [build failed]
FAIL
make[1]: *** [Makefile.Common:49: test] Error 2
make[1]: Leaving directory '/tmp/opentelemetry-collector-contrib'
make: *** [Makefile:327: check-contrib] Error 2

How can we proceed from here?

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 7 days.

[github-actions]

Closed as inactive. Feel free to reopen if this PR is still being worked on.