apmtelemetrygen: add rewrite flag (#191)

add  -rewrite-ids and -rewrite-timestamps flags, to control
disabling rewriting IDs and Timestamps when replaying
canned data.

Useful for troubleshooting metering issue as it removes
any variance from the output.

By default they are set to true to preserve current behavior.

cmd/apmtelemetrygen/main.go

@@ -138,6 +138,8 @@ func newRunCmd() *cobra.Command {
 	cmd.Flags().StringVar(&options.EventRate, "event-rate", "0/s", "Must be in the format <number of events>/<time>. <time> is parsed")
 	cmd.Flags().IntVar(&options.Iterations, "iterations", 1, "The number of times to replay the canned data for")
 	cmd.Flags().BoolVar(&options.IgnoreErrors, "ignore-errors", false, "Ignore HTTP errors while sending events")
+	cmd.Flags().BoolVar(&options.RewriteIDs, "rewrite-ids", true, "Enable or disable rewriting IDs of stored events in ouput.")
+	cmd.Flags().BoolVar(&options.RewriteTimestamps, "rewrite-timestamps", true, "Enable or disable rewriting timestamps of stored events in ouput.")
 	return &cmd
 }
 
@@ -152,6 +154,14 @@ type runOptions struct {
 	EventRate    string
 	Iterations   int
 	IgnoreErrors bool
+	// Specific if to rewrite IDs in stored events.
+	// This allows replaying the data with no variance on event IDs.
+	// Useful for troubleshooting.
+	RewriteIDs bool
+	// Specific if to rewrite timestamps in stored events.
+	// This allows replaying the data with no variance on event timestamps.
+	// Useful for troubleshooting.
+	RewriteTimestamps bool
 }
 
 func (opts *runOptions) toEventHandlerParams(logger *zap.Logger) (loadgen.EventHandlerParams, error) {
@@ -173,8 +183,8 @@ func (opts *runOptions) toEventHandlerParams(logger *zap.Logger) (loadgen.EventH
 		Limiter:      loadgen.GetNewLimiter(burst, interval),
 		Rand:         rand.New(rand.NewSource(time.Now().UnixNano())),
 
-		RewriteIDs:        true,
-		RewriteTimestamps: true,
+		RewriteIDs:        opts.RewriteIDs,
+		RewriteTimestamps: opts.RewriteTimestamps,
 	}, nil
 }