fix: replace segment name from env on BeginSegment

[nicolascb]

It is not clear from the official documentation that this variable is used only in HTTP situations:

Environment variables

You can use environment variables to configure the X-Ray SDK for Go. The SDK supports the following variables.

    AWS_XRAY_TRACING_NAME – Set the service name that the SDK uses for segments.

This PR applies the same logic so that the segment name is replaced by the environment variable AWS_XRAY_TRACING_NAME.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[nicolascb]

That makes sense? @bhautikpip

[bhautikpip]

Yes, I think this check will be useful when we directly call xray.BeginSegment() API and for other middlewares like http and fasthttp handler we are checking this env var in xray.NewFixedSegmentNamer method. So I think for parity with other checks this would be a good change to add.

[bhautikpip]

Should we remove the check from here

aws-xray-sdk-go/xray/handler.go

Line 39 in 015dc2e

if fName := os.Getenv("AWS_XRAY_TRACING_NAME"); fName != "" {

and keep it only at xray.BeginSegment() method ? I think in the case of http handler if customer has used AWS_XRAY_TRACING_NAME then the same condition will be evaluated twice.

[nicolascb]

Should we remove the check from here

aws-xray-sdk-go/xray/handler.go

Line 39 in 015dc2e

if fName := os.Getenv("AWS_XRAY_TRACING_NAME"); fName != "" {

and keep it only at xray.BeginSegment() method ? I think in the case of http handler if customer has used AWS_XRAY_TRACING_NAME then the same condition will be evaluated twice.

Sorry @bhautikpip, but I did not understand.

If you remove this condition, what about situations where we don't use xray.BeginSegment?

As in this example:

[bhautikpip]

So basically xray.Handler method calls xray.NewSegmentFromHeader (https://github.com/aws/aws-xray-sdk-go/blob/master/xray/handler.go#L94) method and that method calls xray.BeginSegmentWithSampling (

aws-xray-sdk-go/xray/segment.go

Line 77 in 9d2f59c

func BeginSegmentWithSampling(ctx context.Context, name string, r *http.Request, traceHeader *header.Header) (context.Context, *Segment) {

). so basically middlewares like http end up calling BeginSegmentWithSampling method so if we keep this condition inside BeginSegmentWithSampling then we can remove this condition inside NewFixedSegmentNamer. Hope this makes sense!

[nicolascb]

@bhautikpip Yes you are right.

I will work on it, thanks for the review

[nicolascb]

Done de8e0b9 @bhautikpip

[bhautikpip]

LGTM :)