based on https://cloud.google.com/trace/docs/setup/go
https://cloud.google.com/trace/docs/iam#roles
Set GOOGLE_APPLICATION_CREDENTIALS and GOOGLE_CLOUD_PROJECT env vars.
# make bench
go test -bench=. -cpu=4 -benchmem -benchtime=100x
goos: darwin
goarch: amd64
pkg: gcp-trace
cpu: Intel(R) Core(TM) i5-1038NG7 CPU @ 2.00GHz
BenchmarkWithoutTrace-4 100 53391358 ns/op 26127 B/op 127 allocs/op
--- BENCH: BenchmarkWithoutTrace-4
BenchmarkWithTrace-4 100 53548751 ns/op 82529 B/op 1118 allocs/op
--- BENCH: BenchmarkWithTrace-4
PASS
ok gcp-trace 11.617s