Add custom name support to `newrelic.ExternalSegment` about go-agent

[willnewrelic]

Hi @justiandre

Thanks for writing in! Host level external metrics do not have the specificity you need: You want to be able to add the first segment of the path to the metric, or control the name of the metric directly. I see how that would be useful!

I have brought this idea to the attention of our product management.

For the time being, I recommend using the URL field of the ExternalSegment: You can create a fictitious url with the first path segment in the hostname. Example:

	s := newrelic.ExternalSegment{
		StartTime: newrelic.StartSegmentNow(txn),
		URL:       "http://api_gateway_service_02",
	}
	// external call here
	s.End()

Just be careful to ensure that URL contains a scheme: It will be parsed by the standard library's url.Parse.

[justiandre]

Hello, how's the progress of this issue?

[willnewrelic]

Hey @justiandre

Here is some code that demonstrates the interim solution described above: This code creates external metrics External/example.com_zip/all from requests to http://example.com/zip/zap.

func startExternal(txn newrelic.Transaction, req *http.Request) *newrelic.ExternalSegment {
	segment := newrelic.StartExternalSegment(txn, req)
	if u := req.URL; nil != u {
		var firstSegment string
		if s := strings.Split(strings.TrimPrefix(u.Path, "/"), "/"); len(s) > 0 {
			firstSegment = s[0]
		}
		nu := url.URL{
			Scheme: u.Scheme,
			Host:   u.Host + "_" + firstSegment,
		}
		segment.URL = nu.String()
	}
	return segment
}

func doRequest(txn newrelic.Transaction) {
	client := &http.Client{}
	request, _ := http.NewRequest("GET", "http://example.com/zip/zap", nil)
	segment := startExternal(txn, request)
	defer segment.End()
	resp, err := client.Do(request)
	if nil != err {
		return
	}
	defer resp.Body.Close()
	fmt.Println(resp.StatusCode)
}

We acknowledge that this is bothersome, and we are discussing improvements and additional ExternalSegment fields!

[justiandre]

Hey @justiandre

Here is some code that demonstrates the interim solution described above: This code creates external metrics External/example.com_zip/all from requests to http://example.com/zip/zap.

func startExternal(txn newrelic.Transaction, req *http.Request) *newrelic.ExternalSegment {
	segment := newrelic.StartExternalSegment(txn, req)
	if u := req.URL; nil != u {
		var firstSegment string
		if s := strings.Split(strings.TrimPrefix(u.Path, "/"), "/"); len(s) > 0 {
			firstSegment = s[0]
		}
		nu := url.URL{
			Scheme: u.Scheme,
			Host:   u.Host + "_" + firstSegment,
		}
		segment.URL = nu.String()
	}
	return segment
}

func doRequest(txn newrelic.Transaction) {
	client := &http.Client{}
	request, _ := http.NewRequest("GET", "http://example.com/zip/zap", nil)
	segment := startExternal(txn, request)
	defer segment.End()
	resp, err := client.Do(request)
	if nil != err {
		return
	}
	defer resp.Body.Close()
	fmt.Println(resp.StatusCode)
}

We acknowledge that this is bothersome, and we are discussing improvements and additional ExternalSegment fields!

Today we are doing so, but it is a very very inelegant solution and that does not make sense !! It is difficult to generalize it into other components.

[willnewrelic]

Hi @justiandre

We just released version 2.9.0 which includes changes you might find useful!

ExternalSegment now has three new optional fields: Host, Procedure, and Library.

• Host is used for external metrics, transaction trace segment names, and span event names.
• Procedure is used for transaction breakdown metrics.
• Library is used for external metrics and the "component" span attribute. "http" is the default.

The easier thing to do is just populate Host field with the name you would like to see:

    segment := newrelic.ExternalSegment{
        StartTime: txn.StartSegmentNow(),
        Host:      "api_gateway_service_01",  // slashes are not allowed, so use underscores
    }

Alternatively, you can populate both Host and Procedure. Unfortunately, the External tab metrics do not include Procedure: It will only appear in the metrics in each transaction breakdown.

    segment := newrelic.ExternalSegment{
        StartTime: txn.StartSegmentNow(),
        Host:      "api_gateway",
        Procedure: "service_01",
    }

We hope these new fields make things better for you!

[willnewrelic]

Hi @justiandre !

I hope the new ExternalSegment fields are working for you! I'm going to close this: Don't hesitate to re-open this or reach out if you would like to discuss further!