Use custom VCL for Pass/!Pass conditions

We’ve now exceeded our max number of characters for a condition in the Fastly API, and we need to make it larger to accommodate regex conditionals that can match on any of the routes in www currently.

This fixes the issue by moving the conditions – and the states that are affected by it, like setting the backend or cache ttls – to two custom vcl files that are updated via the Fastly API. One is for the `vcl_rev` config, and one is for the `vcl_fetch` config.

bin/lib/fastly-extended.js

@@ -166,5 +166,94 @@ module.exports = function (apiKey, serviceId) {
         this.request('PUT', url, cb);
     };
 
+    /**
+     * Upsert a custom vcl file. Attempts a PUT, and falls back
+     * to POST if not there already.
+     *
+     * @param {number}   version current version number for fastly service
+     * @param {string}   name    name of the custom vcl file to be upserted
+     * @param {string}   vcl     stringified custom vcl to be uploaded
+     * @param {Function} cb      function that takes in two args: err, response
+     */
+    fastly.setCustomVCL = function (version, name, vcl, cb) {
+        if (!this.serviceId) {
+            return cb('Failed to set response object. No serviceId configured');
+        }
+
+        var url = this.getFastlyAPIPrefix(this.serviceId, version) + '/vcl/' + name;
+        var postUrl = this.getFastlyAPIPrefix(this.serviceId, version) + '/vcl';
+        var content = {content: vcl};
+        return this.request('PUT', url, content, function (err, response) {
+            if (err && err.statusCode === 404) {
+                content.name = name;
+                this.request('POST', postUrl, content, function (err, response) {
+                    if (err) {
+                        return cb('Failed while adding custom vcl \"' + name + '\": ' + err);
+                    }
+                    return cb(null, response);
+                });
+                return;
+            }
+            if (err) {
+                return cb('Failed to update custom vcl \"' + name + '\": ' + err);
+            }
+            return cb(null, response);
+        }.bind(this));
+    };
+
+    /**
+     * Returns custom vcl configuration as a string for setting the backend
+     * of a request to the given backend/host.
+     *
+     * @param {string} backend   name of the backend declared in fastly
+     * @param {string} host      name of the s3 bucket to be set as the host
+     * @param {string} condition condition under which backend should be set
+     */
+    fastly.setBackend = function (backend, host, condition) {
+        return '' +
+            'if (' + condition + ') {\n' +
+            '    set req.backend = ' + backend + ';\n' +
+            '    set req.http.host = \"' + host + '\";\n' +
+            '}\n';
+    };
+
+    /**
+     * Returns custom vcl configuration as a string for headers that
+     * should be added for the condition in which a request is forwarded.
+     *
+     * @param {string} condition condition under which to set pass headers
+     */
+    fastly.setForwardHeaders = function (condition) {
+        return '' +
+            'if (' + condition + ') {\n' +
+            '    if (!req.http.Fastly-FF) {\n' +
+            '        if (req.http.X-Forwarded-For) {\n' +
+            '            set req.http.Fastly-Temp-XFF = req.http.X-Forwarded-For \", \" client.ip;\n' +
+            '        } else {\n' +
+            '            set req.http.Fastly-Temp-XFF = client.ip;\n' +
+            '        }\n' +
+            '    } else {\n' +
+            '        set req.http.Fastly-Temp-XFF = req.http.X-Forwarded-For;\n' +
+            '    }\n' +
+            '    set req.grace = 60s;\n' +
+            '    return(pass);\n' +
+            '}\n';
+    };
+
+    /**
+     * Returns custom vcl configuration as a string that sets the varnish
+     * Time to Live (TTL) for responses that come from s3.
+     *
+     * @param {string} condition condition under which the response should be set
+     */
+    fastly.setResponseTTL = function (condition) {
+        return '' +
+            'if (' + condition + ') {\n' +
+            '    set beresp.ttl = 0s;\n' +
+            '    set beresp.grace = 0s;\n' +
+            '    return(pass);\n' +
+            '}\n';
+    };
+
     return fastly;
 };