Expose Varnish cache TTL in configuration. Closes #46

config/environments/development.js

@@ -32,7 +32,8 @@ var config = {
     }
     ,varnish: {
         host: 'localhost',
-        port: 6082
+        port: 6082,
+        ttl: 86400
     }
 };
 

config/environments/production.js

@@ -24,7 +24,8 @@ var config = {
     }
     ,varnish: {
         host: 'localhost',
-        port: 6082
+        port: 6082,
+        ttl: 86400
     }
 };
 

config/environments/test.js

@@ -27,7 +27,8 @@ var config = {
     }
     ,varnish: {
         host: '',
-        port: null
+        port: null,
+        ttl: 86400
     }
 };
 

lib/cartodb/cartodb_windshaft.js

@@ -8,10 +8,11 @@ var CartodbWindshaft = function(serverOptions) {
 
     // set the cache chanel info to invalidate the cache on the frontend server
     serverOptions.afterTileRender = function(req, res, tile, headers, callback) {
+        var ttl = global.environment.varnish.ttl || 86400;
         Cache.generateCacheChannel(req, function(channel){
             res.header('X-Cache-Channel', channel);
             res.header('Last-Modified', new Date().toUTCString());
-            res.header('Cache-Control', 'no-cache,max-age=86400,must-revalidate, public');
+            res.header('Cache-Control', 'no-cache,max-age='+ttl+',must-revalidate, public');
             callback(null, tile, headers);
         });
     };