examples: add varnish-4.vcl

Well, I'm fumbling along with this config.  Might as well
fumble along with it publically :)

diff --git a/examples/varnish-4.vcl b/examples/varnish-4.vcl
new file mode 100644 (file)
index 0000000..7439679
--- /dev/null
+++ b/examples/varnish-4.vcl
@@ -0,0 +1,74 @@
+# Example VCL for Varnish 4.0 with public-inbox WWW code
+# This is based on what shipped for 3.x a long time ago (I think)
+# and I'm hardly an expert in VCL (nor should we expect anybody
+# who maintains a public-inbox HTTP interface to be).
+#
+# It seems to work for providing some protection from traffic
+# bursts; but perhaps the public-inbox WWW interface can someday
+# provide enough out-of-the-box performance that configuration
+# of an extra component is pointless.
+
+vcl 4.0;
+backend default {
+       .host = "127.0.0.1";
+       .port = "280";
+}
+
+sub vcl_recv {
+       if (req.restarts == 0) {
+               if (req.http.x-forwarded-for) {
+                       set req.http.X-Forwarded-For =
+                       req.http.X-Forwarded-For + ", " + client.ip;
+               } else {
+                       set req.http.X-Forwarded-For = client.ip;
+               }
+       }
+       if (req.method != "GET" &&
+                       req.method != "HEAD" &&
+                       req.method != "PUT" &&
+                       req.method != "POST" &&
+                       req.method != "TRACE" &&
+                       req.method != "OPTIONS" &&
+                       req.method != "DELETE") {
+               /* Non-RFC2616 or CONNECT which is weird. */
+               return (pipe);
+       }
+       if (req.method != "GET" && req.method != "HEAD") {
+               /* We only deal with GET and HEAD by default */
+               return (pass);
+       }
+       if (req.http.Authorization || req.http.Cookie) {
+               /* Not cacheable by default */
+               return (pass);
+       }
+       return (hash);
+}
+
+sub vcl_hash {
+       hash_data(req.url);
+       if (req.http.host) {
+               hash_data(req.http.host);
+       } else {
+               hash_data(server.ip);
+       }
+       if (req.http.X-Forwarded-Proto) {
+               hash_data(req.http.X-Forwarded-Proto);
+       }
+       return (lookup);
+}
+
+sub vcl_backend_response {
+       set beresp.grace = 60s;
+       set beresp.do_stream = true;
+       if (beresp.ttl <= 0s ||
+               beresp.http.Set-Cookie ||
+               beresp.http.Vary == "*") {
+               /* Mark as "Hit-For-Pass" for the next 2 minutes */
+               set beresp.ttl = 120 s;
+               set beresp.uncacheable = true;
+               return (deliver);
+       } else {
+               set beresp.ttl = 10s;
+       }
+       return (deliver);
+}