Add support for Brotli static compression

Author: vvuksan

etc/vcl_snippets/fetch.vcl

@@ -52,7 +52,9 @@
             if (!beresp.http.Vary ~ "Accept-Encoding") {
                 set beresp.http.Vary:Accept-Encoding = "";
             }
-            if (req.http.Accept-Encoding == "gzip") {
+            if (req.http.Accept-Encoding == "br") {
+                set beresp.brotli = true;
+            } else if (req.http.Accept-Encoding == "gzip") {
                 set beresp.gzip = true;
             }
         }

etc/vcl_snippets/recv.vcl

@@ -106,6 +106,13 @@
         set req.http.Https = "on";
     }
 
+    # Add support for Brotli static compression
+    if (req.http.Fastly-Orig-Accept-Encoding) {
+        if (req.http.Fastly-Orig-Accept-Encoding ~ "\bbr\b") {
+            set req.http.Accept-Encoding = "br";
+        }
+    }
+
     if (fastly.ff.visits_this_service > 0) {
         # disable ESI processing on Origin Shield
         set req.esi = false;