chore(version-info): add offline-build support

Previously it was slow and problematic to run builds if you were not connected
to the internet because the build scripts make requests to github and the
Google CDN to find out version information.

You can now disable these requests by setting the NG1_BUILD_NO_REMOTE_VERSION_REQUESTS
environment variable to a non-empty value

Closes #14769

Author: petebacondarwin

lib/versions/version-info.js

@@ -6,6 +6,10 @@ var shell = require('shelljs');
 var semver = require('semver');
 var _ = require('lodash');
 
+var process = require('process');
+// We are only interested in whether this environment variable exists, hence the !!
+var NO_REMOTE_REQUESTS = !!process.env['NG1_BUILD_NO_REMOTE_VERSION_REQUESTS'];
+
 var currentPackage, previousVersions, cdnVersion, gitRepoInfo;
 
 
@@ -96,12 +100,12 @@ var getTaggedVersion = function() {
  * @return {Array.<SemVer>} The collection of previous versions
  */
 var getPreviousVersions =  function() {
-  // always use the remote tags as the local clone might
+  // If we are allowing remote requests then use the remote tags as the local clone might
   // not contain all commits when cloned with git clone --depth=...
-  // Needed e.g. for Travis
+  // Otherwise just use the tags in the local repository
   var repo_url = currentPackage.repository.url;
-  var tagResults = shell.exec('git ls-remote --tags ' + repo_url,
-                              {silent: true});
+  var query = NO_REMOTE_REQUESTS ? 'git tag' : 'git ls-remote --tags ' + repo_url;
+  var tagResults = shell.exec(query, {silent: true});
   if (tagResults.code === 0) {
     return _(tagResults.output.match(/v[0-9].*[0-9]$/mg))
       .map(function(tag) {
@@ -138,15 +142,20 @@ var getCdnVersion = function() {
     .reverse()
     .reduce(function(cdnVersion, version) {
       if (!cdnVersion) {
-        // Note: need to use shell.exec and curl here
-        // as version-infos returns its result synchronously...
-        var cdnResult = shell.exec('curl http://ajax.googleapis.com/ajax/libs/angularjs/' + version + '/angular.min.js ' +
-                  '--head --write-out "%{http_code}" -o /dev/null -silent',
-                                    {silent: true});
-        if (cdnResult.code === 0) {
-          var statusCode = cdnResult.output.trim();
-          if (statusCode === '200') {
-            cdnVersion = version;
+        if (NO_REMOTE_REQUESTS) {
+          // We do not want to make any remote calls to the CDN so just use the most recent version
+          cdnVersion = version;
+        } else {
+          // Note: need to use shell.exec and curl here
+          // as version-infos returns its result synchronously...
+          var cdnResult = shell.exec('curl http://ajax.googleapis.com/ajax/libs/angularjs/' + version + '/angular.min.js ' +
+                    '--head --write-out "%{http_code}" -o /dev/null -silent',
+                                      {silent: true});
+          if (cdnResult.code === 0) {
+            var statusCode = cdnResult.output.trim();
+            if (statusCode === '200') {
+              cdnVersion = version;
+            }
           }
         }
       }
@@ -204,3 +213,13 @@ exports.gitRepoInfo = gitRepoInfo = getGitRepoInfo();
 exports.previousVersions = previousVersions = getPreviousVersions();
 exports.cdnVersion = cdnVersion = getCdnVersion();
 exports.currentVersion = getTaggedVersion() || getSnapshotVersion();
+
+if (NO_REMOTE_REQUESTS) {
+  console.log('==============================================================================================');
+  console.log('Running with no remote requests for version data:');
+  console.log(' - this is due to the "NG1_BUILD_NO_REMOTE_VERSION_REQUESTS" environment variable being defined.');
+  console.log(' - be aware that the generated docs may not have valid or the most recent version information.');
+  console.log('==============================================================================================');
+}
+console.log('CDN version:', cdnVersion.raw);
+console.log('Current version:', exports.currentVersion.raw);