Minimal Varnish VCL suitable for most needs

example.vcl

# This is a perfectly good template to get started with Varnish.
# Well behaved sites will get pretty decent results from this, and it
# should work for the vast majority of web sites out there.

# This bit is mandatory. It will say "4.0" even for Varnish 4.1.
# (don't ask)
vcl 4.0;

# This is where your content lives. Adjust it to point at your web server.
backend foo {
	.host = "127.0.0.1";
	.port = "8080";
}

# The only thing stopping Varnish from caching properly by default in most
# cases is the presence of cookies. Strip them, and voila, cache works.
sub vcl_recv {
	# We leave cookies for content under "/user".
	if (req.url !~ "^/user") {
		unset req.http.cookie;
	}
}

# That's all you need, but you might want to start adjusting cache duration
# too! You can do that by emitting "Cache-Control: s-maxage=123" from your
# backend server, telling Varnish to cache for 123 seconds. That requires 0
# configuration, but the following snippet removes "s-maxage" from the
# response before it is sent to the client, so as not to confuse other
# proxy servers between you and the client.
sub strip_smaxage {
	# Remove white space
	set beresp.http.cache-control = regsuball(beresp.http.cache-control, " ","");
	# strip s-maxage - Varnish has already used it
	set beresp.http.cache-control = regsub(beresp.http.cache-control, "s-maxage=[0-9]+\b","");
	# Strip extra commas
	set beresp.http.cache-control = regsub(beresp.http.cache-control, "(^,|,$|,,)", "");
}

# This just calls the above function at the appropriate time.
sub vcl_backend_response {
	call strip_smaxage;
}

# You can read more about control Varnish through headers at 
# https://varnishfoo.info/chapter-2.html