chore(version-info): disable remote requests when offline

When the internet is not accessible build scripts are unnecessarily slow
because of failed attempts to download git tag and CDN version information
from remote servers.

This commit does a synchronous check of internet connectivity before attempting
any remote requests.

Closes #14759

Author: petebacondarwin

lib/versions/is-online.js

@@ -0,0 +1,7 @@
+"use strict";
+
+var isOnlineAsync = require('is-online');
+
+isOnlineAsync(function(err, isOnline) {
+  console.log(isOnline ? 'online' : 'offline');
+});

lib/versions/version-info.js

@@ -1,13 +1,16 @@
 'use strict';
 
+var childProcess = require('child_process');
 var fs = require('fs');
 var path = require('path');
 var shell = require('shelljs');
 var semver = require('semver');
 var _ = require('lodash');
 
 var currentPackage, previousVersions, cdnVersion, gitRepoInfo;
-
+var connectivityStatus = childProcess.execSync('node is-online.js', { cwd: __dirname, encoding: 'utf8' }).trim();
+var isOnline = connectivityStatus == 'online';
+console.log('Running ' + connectivityStatus);
 
 /**
  * Load information about this project from the package.json
@@ -100,58 +103,68 @@ var getPreviousVersions =  function() {
   // not contain all commits when cloned with git clone --depth=...
   // Needed e.g. for Travis
   var repo_url = currentPackage.repository.url;
-  var tagResults = shell.exec('git ls-remote --tags ' + repo_url,
-                              {silent: true});
-  if (tagResults.code === 0) {
-    return _(tagResults.output.match(/v[0-9].*[0-9]$/mg))
-      .map(function(tag) {
-        var version = semver.parse(tag);
-        return version;
-      })
-      .filter()
-      .map(function(version) {
-        // angular.js didn't follow semantic version until 1.20rc1
-        if ((version.major === 1 && version.minor === 0 && version.prerelease.length > 0) || (version.major === 1 && version.minor === 2 && version.prerelease[0] === 'rc1')) {
-          version.version = [version.major, version.minor, version.patch].join('.') + version.prerelease.join('');
-          version.raw = 'v' + version.version;
-        }
-        version.docsUrl = 'http://code.angularjs.org/' + version.version + '/docs';
-        // Versions before 1.0.2 had a different docs folder name
-        if (version.major < 1 || (version.major === 1 && version.minor === 0 && version.patch < 2)) {
-          version.docsUrl += '-' + version.version;
-          version.isOldDocsUrl = true;
-        }
-        return version;
-      })
-      .sort(semver.compare)
-      .value();
+  if (isOnline) {
+    console.log('looking up remote git tags...');
+    var tagResults = shell.exec('git ls-remote --tags ' + repo_url,
+                                {silent: true});
+    if (tagResults.code === 0) {
+      return _(tagResults.output.match(/v[0-9].*[0-9]$/mg))
+        .map(function(tag) {
+          var version = semver.parse(tag);
+          return version;
+        })
+        .filter()
+        .map(function(version) {
+          // angular.js didn't follow semantic version until 1.20rc1
+          if ((version.major === 1 && version.minor === 0 && version.prerelease.length > 0) || (version.major === 1 && version.minor === 2 && version.prerelease[0] === 'rc1')) {
+            version.version = [version.major, version.minor, version.patch].join('.') + version.prerelease.join('');
+            version.raw = 'v' + version.version;
+          }
+          version.docsUrl = 'http://code.angularjs.org/' + version.version + '/docs';
+          // Versions before 1.0.2 had a different docs folder name
+          if (version.major < 1 || (version.major === 1 && version.minor === 0 && version.patch < 2)) {
+            version.docsUrl += '-' + version.version;
+            version.isOldDocsUrl = true;
+          }
+          return version;
+        })
+        .sort(semver.compare)
+        .value();
+    }
   } else {
-    return [];
+    console.log('-- skipping remote git tag lookup');
   }
+  return [];
 };
 
 var getCdnVersion = function() {
-  return _(previousVersions)
-    .filter(function(tag) {
-      return semver.satisfies(tag, currentPackage.branchVersion);
-    })
-    .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 (isOnline) {
+    console.log('searching for CDN versions...');
+    return _(previousVersions)
+      .filter(function(tag) {
+        return semver.satisfies(tag, currentPackage.branchVersion);
+      })
+      .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') {
+              console.log('-- found CDN version ' + version);
+              cdnVersion = version;
+            }
           }
         }
-      }
-      return cdnVersion;
-    }, null);
+        return cdnVersion;
+      }, null);
+  } else {
+    console.log('-- skipping CDN version lookup');
+  }
 };
 
 /**
@@ -198,7 +211,6 @@ var getSnapshotVersion = function() {
   return version;
 };
 
-
 exports.currentPackage = currentPackage = getPackage();
 exports.gitRepoInfo = gitRepoInfo = getGitRepoInfo();
 exports.previousVersions = previousVersions = getPreviousVersions();