Varnish: How do You Know Your Backend Responses Properly?

You might use varnishstat to monitor backend healthy status, but that is not so directly, instead you can do this:

# varnishlog -g session -C -q 'ReqHeader:Host ~ "example.com"' | grep Status
--  RespStatus     200
--  RespStatus     200
--  RespStatus     200
--  RespStatus     200
--- BerespStatus   200
--- ObjStatus      200
--  RespStatus     200
--  RespStatus     200
--  RespStatus     200
--  RespStatus     200
--- BerespStatus   200
--- ObjStatus      200
--  RespStatus     200
--- BerespStatus   200
--- ObjStatus      200
--  RespStatus     200
--- BerespStatus   200
--- ObjStatus      200
--  RespStatus     200
--- BerespStatus   200
...

Convenient, right? you can tail and grep whatever you want of varnishlog’s output.