Log uses of isolate archive and exparchive when 'chromium' build tag is set.

client/cmd/isolate/isolate_event_logger.go

Index: client/cmd/isolate/isolate_event_logger.go
diff --git a/client/cmd/isolate/isolate_event_logger.go b/client/cmd/isolate/isolate_event_logger.go
index 4878f1d4ac7894d542bd00c29f5b8856b5e1cbd9..1a68933607c37bac27909ea4fa0a2330cc84fc68 100644
--- a/client/cmd/isolate/isolate_event_logger.go
+++ b/client/cmd/isolate/isolate_event_logger.go
@@ -13,8 +13,35 @@ import (
 	"github.com/golang/protobuf/proto"
 	"github.com/luci/luci-go/common/eventlog"
 	logpb "github.com/luci/luci-go/common/eventlog/proto"
+	"github.com/luci/luci-go/common/logging"
 )
 
+// When --eventlog-endpoint=auto, we decide to send eventlogs based on whether --isolate-server matches prodIsolateServer

[M-A Ruel, 2017/06/08 14:06:05]

I don't understand why we don't want to log everywhere? Also there's many more
"prod" instances and I'd prefer not have to hardcode them here.

[mcgreevy, 2017/06/08 23:19:01]

The reason is that luci-go is an open source project, and I don't want to log
usages of it that are unrelated to the chromium project. Here's another idea,
though: rather than checking which isolateserver is being used, I could switch
logging on via a build tag, and enable that build tag when building the isolate
binary that we upload to GCS. That way the binary that we build for our own
purposes will automatically log, whereas when it's built by anyone else, it
wont.  WDYT?

+const prodIsolateServer = "https://isolateserver.appspot.com"
+
+// eventlogEndpoint returns a destination URL for eventlogs, based on the contents of
+// the endpointFlag and isolateServerFlag.
+func eventlogEndpoint(ctx context.Context, endpointFlag string, isolateServerFlag string) string {
+	switch endpointFlag {
+	case "auto":
+		if isolateServerFlag == prodIsolateServer {
+			// If we are uploading to the prod server, we log this activity.
+			msg := "Automatically logging usage statistics to %s. If this is not desired, then set --eventlog-endpoint=none"
+			logging.Infof(ctx, msg, eventlog.ProdEndpoint)
+			return eventlog.ProdEndpoint
+		}
+		return ""
+	case "test":
+		return eventlog.TestEndpoint
+	case "prod":
+		return eventlog.ProdEndpoint
+	case "none":
+		return ""
+	default:
+		return endpointFlag
+	}
+}
+
 type syncLogger interface {
 	LogSync(ctx context.Context, events ...*eventlog.ChromeInfraLogEvent) error
 	NewLogEvent(ctx context.Context, eventTime eventlog.TypedTime) *eventlog.ChromeInfraLogEvent
@@ -30,10 +57,11 @@ type IsolateEventLogger struct {
 }
 
 // NewLogger returns an IsolateEventLogger which logs to the specified endpoint.
+// endpoint is the URL to which logs will be sent.
 func NewLogger(ctx context.Context, endpoint string) *IsolateEventLogger {
 	l := &IsolateEventLogger{}
-	if host := eventlogEndpoint(endpoint); host != "" {
-		l.client = eventlog.NewClient(ctx, host)
+	if endpoint != "" {
+		l.client = eventlog.NewClient(ctx, endpoint)
 	}
 	return l
 }
@@ -62,17 +90,6 @@ func (l *IsolateEventLogger) logStats(ctx context.Context, op *logpb.IsolateClie
 	return l.client.LogSync(ctx, event)
 }
 
-func eventlogEndpoint(endpointFlag string) string {
-	switch endpointFlag {
-	case "test":
-		return eventlog.TestEndpoint
-	case "prod":
-		return eventlog.ProdEndpoint
-	default:
-		return endpointFlag
-	}
-}
-
 // buildbotInfo contains information about the build in which this command was run.
 type buildbotInfo struct {
 	// Variables which are not present in the environment are nil.