varnishgather is a simple script designed to gather as much relevant information as possible on a Varnish Cache setup.

Primary platforms so far are Debian-based systems (including Ubuntu) and RHEL-based systems (including CentOS/other derivatives.).

wget -N https://raw.githubusercontent.com/varnish/varnishgather/master/varnishgather
sudo sh ./varnishgather

Varnishgather gathers various statistics, metrics and facts about your system. These are output into a .tar.gz archive file. It is up to you what to do with it.

The tar-ball currently contains a set of text files for different probes or tests, and a small raw varnishlog file which can be reviewed using varnishlog -r.

The probes/tests include information similar to:

• Any VCL files found in /etc/varnish/ (*.vcl, so /etc/varnish/secret is not included)
• Output of dmesg, netstat, ip, iptables, sysctl, free, vmstat, df, mount, lsb_release, uname and possibly similar commands. All with various information-gathering options.
• Any bans currently active
• Any loaded vcl.
• varnishstat -1 output
• panic.show (on CLI) output

As varnishgather is sometimes updated to gather new data, the above list is not meant to be complete, but an illustration of what to expect.

The data is intended to reveal everything and anything Varnish-related. Be it whether or not network problems is causing latency, if cookies is being treated safely, or if features like grace, streaming or ESI are set up correctly.

If there was an easy way to interpret the data, I would've written a script called fixyourvarnishsetup instead ;)

There is no howto for interpreting the data, since there might be nothing to interpret.

The only thing I can say is: use varnishlog -r to read the varnishlog provided.

Yes.