Implement create instance from instance template

src/zone.js

@@ -581,6 +581,7 @@ class Zone extends common.ServiceObject {
    */
   createVM(name, config, callback) {
     const self = this;
+    const query = {};
     const body = Object.assign(
       {
         name: name,
@@ -593,6 +594,10 @@ class Zone extends common.ServiceObject {
       },
       config
     );
+    if (body.template) {
+      query.sourceInstanceTemplate = body.template;
+      delete body.template;
+    }
     if (body.machineType.indexOf('/') === -1) {
       // The specified machineType is only a partial name, e.g. 'n1-standard-1'.
       body.machineType = format('zones/{zoneName}/machineTypes/{machineType}', {
@@ -664,6 +669,7 @@ class Zone extends common.ServiceObject {
       {
         method: 'POST',
         uri: '/instances',
+        qs: query,
         json: body,
       },
       (err, resp) => {

test/zone.js

@@ -775,6 +775,24 @@ describe('Zone', () => {
       ],
     };
 
+    describe('config.template', () => {
+      const CONFIG = {
+        template: '/path/to/template',
+      };
+
+      it('should define sourceInstanceTemplate', done => {
+        zone.request = function (reqOpts) {
+          assert.strictEqual(
+            reqOpts.qs.sourceInstanceTemplate,
+            CONFIG.template
+          );
+          done();
+        };
+
+        zone.createVM(NAME, CONFIG, assert.ifError);
+      });
+    });
+
     describe('config.machineType', () => {
       const CONFIG = {
         machineType: 'f1-micro',