Allowed disabling setting of 'User-Agent' header

refs https://github.com/TryGhost/Toolbox/issues/348
refs https://github.com/TryGhost/Toolbox/issues/301
refs #426

- In certain environments (e.g. web browser) the client might want to disable sending User-Agent variable to avoid errors like in #426.
- This is also a groundwork to have smarter defaults based on the environment - userAgent header would be disabled by default in browser environments as that's the main use case and will be enabled for nodejs environment

Author: naz

packages/content-api/lib/content-api.js

@@ -1,6 +1,8 @@
 import axios from 'axios';
 import packageInfo from '../package.json';
 
+const USER_AGENT_DEFAULT = true;
+
 const packageVersion = packageInfo.version;
 
 const defaultAcceptVersionHeader = 'v5.0';
@@ -50,11 +52,12 @@ const defaultMakeRequest = ({url, method, params, headers}) => {
  * @param {String} options.key
  * @param {String} [options.ghostPath]
  * @param {String|Boolean} options.version - a version string like v3, v4, v5 or boolean value identifying presence of Accept-Version header
+ * @param {Boolean} [options.userAgent] - flag controlling if the 'User-Agent' header should be sent with a request
  * @param {Function} [options.makeRequest]
  */
-export default function GhostContentAPI({url, key, version, ghostPath = 'ghost', makeRequest = defaultMakeRequest}) {
+export default function GhostContentAPI({url, key, version, userAgent, ghostPath = 'ghost', makeRequest = defaultMakeRequest}) {
     if (this instanceof GhostContentAPI) {
-        return GhostContentAPI({url, key, version, ghostPath, makeRequest});
+        return GhostContentAPI({url, key, version, userAgent, ghostPath, makeRequest});
     }
 
     if (version === undefined) {
@@ -100,6 +103,11 @@ export default function GhostContentAPI({url, key, version, ghostPath = 'ghost',
     if (key && !/[0-9a-f]{26}/.test(key)) {
         throw new Error(`${name} Config Invalid: 'key' ${key} must have 26 hex characters`);
     }
+
+    if (userAgent === undefined) {
+        userAgent = USER_AGENT_DEFAULT;
+    }
+
     const api = ['posts', 'authors', 'tags', 'pages', 'settings', 'tiers', 'newsletters', 'offers'].reduce((apiObject, resourceType) => {
         function browse(options = {}, memberToken) {
             return makeApiRequest(resourceType, options, null, memberToken);
@@ -142,7 +150,10 @@ export default function GhostContentAPI({url, key, version, ghostPath = 'ghost',
             Authorization: `GhostMembers ${membersToken}`
         } : {};
 
-        headers['User-Agent'] = `GhostContentSDK/${packageVersion}`;
+        if (userAgent) {
+            headers['User-Agent'] = `GhostContentSDK/${packageVersion}`;
+        }
+
         if (acceptVersionHeader) {
             headers['Accept-Version'] = acceptVersionHeader;
         }

packages/content-api/test/content-api-test/content-api.test.js

@@ -1,6 +1,3 @@
-// Switch these lines once there are useful utils
-// const testUtils = require('./utils');
-
 const should = require('should');
 const sinon = require('sinon');
 
@@ -217,5 +214,28 @@ describe('GhostContentApi', function () {
             should.equal(makeRequestStub.args[0][0].headers['Accept-Version'], 'v5.0');
             should.equal(makeRequestStub.args[0][0].headers['User-Agent'], `GhostContentSDK/${packageVersion}`);
         });
+
+        it('Removes User-Agent header when set to "false"', async function () {
+            const makeRequestStub = sinon.stub().returns(Promise.resolve({
+                data: {
+                    settings: {}
+                }
+            }));
+
+            const api = new GhostContentApi({
+                version: 'canary',
+                url: `http://ghost.local`,
+                key: '0123456789abcdef0123456789',
+                makeRequest: makeRequestStub,
+                userAgent: false
+            });
+
+            await api.settings.browse();
+
+            makeRequestStub.calledOnce.should.be.true();
+            should.equal(makeRequestStub.args[0][0].url, 'http://ghost.local/ghost/api/canary/content/settings/');
+            should.equal(makeRequestStub.args[0][0].headers['Accept-Version'], 'v5.0');
+            should.equal(makeRequestStub.args[0][0].headers['User-Agent'], undefined);
+        });
     });
 });