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You can access performance metrics for Sauce Connect Proxy over an HTTP connection to a local expvar server, which will display the metrics as a JSON file.

Configuring Performance Metric Monitoring 

By default the expvar server listens on localhost:8888, but you can change the interface and port with the --metrics-address command.

--metrics-address :8000 # listens on all the interfaces' port 8080
--metrics-address # listens on port 80

Viewing Performance Metrics

You can view performance metrics by using an HTTP client or web browser to access http://{SauceConnect IP or Localhost:8888}/debug/vars.

Interpreting Performance Metrics

When you access the peformance metrics, you will typically see something like this:

"cmdline": ["/Users/yaroslav/Downloads/sc-4.4.12-osx/bin/sc","-u","User","-k","xxxxxx-xxxx-xxxx-xxx-18e845f4c9a3"],
"http": {
"kgp": 	{
"memstats": {


  • kgp.Connected indicates if the client is connected to the Sauce Connect back-end. This field can be used for monitoring tunnel health.
  • kgp.LastStatusChange is a UNIX timestamp indicating the time of the last connectivity change from the client
  • kgp.ReconnectCount is the number of times the connection to the Sauce Connect backend had to be re-established because of the timeout
  • kgp.RoundTripTimeMs is the application layer latency over the last minute.


  • http.BytesReceived and http.BytesTransmitted are the number of bytes going through the Sauce Connect Proxy client
  • http.NumRequests and http.NumResponses indicate how many request and responses are currently in-flight