Add more summary metrics for varnish

[richwandell]

In the summary I only get 3 data points. Back Conn Failures (worthless), Nuked objects (semi worthless), and Queued Requests (totally worthless)

How can I add hit rate and miss rate to this?

[oppianmatt]

Well I wouldn't call those 3 data points worthless.

• back conn failures used for when you can't connect to backend
• nuked objects means your cache is full, you need more cache in your screenshot
• queued requests is useful for when you have to many requests for the same url to the backend and the backend is going mark it uncacheable you will have an issure.