[META 882] Check classic and OTel agents against serverless

[obltmachine]

See meta issue and spec for the description and details:

• Meta issue: Check classic and OTel agents against serverless apm#882
• Spec issue: [META 882] Spec: Check classic and OTel agents against serverless apm#883

[dmathieu]

I ran a simple app instrumented with the APM client and configured to send its data to a serverless project.

package main

import (
	"io"
	"log"
	"net/http"

	"go.elastic.co/apm/module/apmhttp/v2"
	_ "go.elastic.co/apm/v2"
)

func main() {
	handler := http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
		_, _ = io.WriteString(w, "Hello, world!\n")
	})

	http.Handle("/hello", apmhttp.Wrap(handler))
	err := http.ListenAndServe(":7777", nil)
	if err != nil {
		log.Fatal(err)
	}
}

[dmathieu]

I ran the otel-collector example from otel-go, configured to send its data through OTLP HTTP to a serverless project.