internal/config: use environment variable to set ServiceID

Change-Id: If12c5d54c5c12d52294ef55436c815472dcdc10b
Reviewed-on: https://go-review.googlesource.com/c/pkgsite-metrics/+/465219
Run-TryBot: Julie Qiu <julieqiu@google.com>
Auto-Submit: Julie Qiu <julieqiu@google.com>
Reviewed-by: Julie Qiu <julieqiu@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
diff --git a/internal/config/config.go b/internal/config/config.go
index 37149a7..7329089 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -115,7 +115,7 @@
 	}
 	cfg := &Config{
 		ProjectID:             os.Getenv("GOOGLE_CLOUD_PROJECT"),
-		ServiceID:             "go-ecosystem-worker",
+		ServiceID:             os.Getenv("GO_ECOSYSTEM_SERVICE_ID"),
 		VersionID:             os.Getenv("DOCKER_IMAGE"),
 		LocationID:            "us-central1",
 		StaticPath:            ts,
diff --git a/internal/worker/server.go b/internal/worker/server.go
index dc12419..0fa8bf4 100644
--- a/internal/worker/server.go
+++ b/internal/worker/server.go
@@ -101,7 +101,7 @@
 		return nil, err
 	}
 
-	s.observer, err = observe.NewObserver(ctx, cfg.ProjectID, "go-ecosystem-worker")
+	s.observer, err = observe.NewObserver(ctx, cfg.ProjectID, cfg.ServiceID)
 	if err != nil {
 		return nil, err
 	}