{Storage} az storage copy: Add aka.ms backup links when downloading AzCopy (#30712)

* add a backup using aka.ms links when the static link in CLI fails, keeping the static links in case aka.ms is not working

* lint

Author: calvinhzy

src/azure-cli/azure/cli/command_modules/storage/azcopy/util.py

@@ -60,12 +60,20 @@ def install_azcopy(self, install_location):
         if self.system == 'Windows':
             if platform.machine().endswith('64'):
                 file_url = base_url.format('windows', 'amd64', AZCOPY_VERSION, 'zip')
+                if _verify_url(file_url) is None:
+                    file_url = _verify_url('https://aka.ms/InstallAzCopyForCLIWindowsX64')
             else:
                 file_url = base_url.format('windows', '386', AZCOPY_VERSION, 'zip')
+                if _verify_url(file_url) is None:
+                    file_url = _verify_url('https://aka.ms/InstallAzCopyForCLIWindows')
         elif self.system == 'Linux':
             file_url = base_url.format('linux', 'amd64', AZCOPY_VERSION, 'tar.gz')
+            if _verify_url(file_url) is None:
+                file_url = _verify_url('https://aka.ms/InstallAzCopyForCLILinux')
         elif self.system == 'Darwin':
             file_url = base_url.format('darwin', 'amd64', AZCOPY_VERSION, 'zip')
+            if _verify_url(file_url) is None:
+                file_url = _verify_url('https://aka.ms/InstallAzCopyForCLIDarwin')
         else:
             raise CLIError('Azcopy ({}) does not exist.'.format(self.system))
         try:
@@ -74,8 +82,10 @@ def install_azcopy(self, install_location):
             os.chmod(install_location,
                      os.stat(install_location).st_mode | stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH)
         except OSError as err:
+            azcopy_install_guide = 'https://learn.microsoft.com/azure/storage/common/storage-use-azcopy-v10'
             raise CLIError('Connection error while attempting to download azcopy {}. You could also install the '
-                           'specified azcopy version to {} manually. ({})'.format(AZCOPY_VERSION, install_dir, err))
+                           'specified azcopy version to {} manually following the guide here: {} '
+                           '({})'.format(AZCOPY_VERSION, install_dir, azcopy_install_guide, err))
 
     def check_version(self):
         try:
@@ -218,6 +228,7 @@ def _get_default_install_location():
 
 def _urlretrieve(url, install_location):
     import io
+    logger.warning('Downloading AzCopy from %s', url)
     req = urlopen(url)
     compressedFile = io.BytesIO(req.read())
     if url.endswith('zip'):
@@ -235,3 +246,15 @@ def _urlretrieve(url, install_location):
                         f.write(tar.extractfile(tarinfo).read())
     else:
         raise CLIError('Invalid downloading url {}'.format(url))
+
+
+def _verify_url(url):
+    from urllib.error import HTTPError, URLError
+    try:
+        response = urlopen(url)
+        if response.code == 200:
+            return response.url
+        return None
+    except (HTTPError, URLError):
+        logger.warning('There is an error downloading from the url: %s', url)
+        return None