Make Firefox nightly download more robust.

download_firefox_nightly.py

Index: download_firefox_nightly.py
===================================================================
--- download_firefox_nightly.py	(revision 293856)
+++ download_firefox_nightly.py	(working copy)
@@ -5,11 +5,14 @@
 
 """Downloads a Firefox Nightly build for the current platform."""
 
+import datetime
+import glob
 import os
 import shutil
 import sys
 import subprocess
 import tarfile
+import time
 import zipfile
 
 from optparse import OptionParser
@@ -23,38 +26,61 @@
 from mozdownload import scraper
 
 
-def main():
-  usage = 'usage: %prog -t <target_dir>'
-  parser = OptionParser(usage)
-  parser.add_option('-t', '--target-dir',
-                    help=('Target directory to put the downloaded and extracted'
-                          ' folder with the Firefox Nightly build in.'))
-  parser.add_option('-f', '--force', action='store_true',
-                    help=('Force download even if the current nightly is '
-                          'already downloaded.'))
-  options, _args = parser.parse_args()
-  if not options.target_dir:
-    parser.error('You must specify the target directory.')
+def _Touch(a_file):
+  with open(a_file, 'a'):
+    os.utime(a_file, None)
 
-  target_dir = options.target_dir
-  if not os.path.isdir(target_dir):
-    os.mkdir(target_dir)
 
-  downloader = scraper.DailyScraper(directory=target_dir, version=None)
-  firefox_archive = os.path.join(target_dir,
-                                 downloader.build_filename(downloader.binary))
+def _FindFallbackFirefoxBuild(target_dir):
+  firefox_archives = glob.glob(os.path.join(target_dir, '*tar.bz2'))
+  if not firefox_archives:
+    return None
 
-  if os.path.exists(firefox_archive) and not options.force:
-    print 'Skipping download as %s is already downloaded.' % firefox_archive
-    return 0
+  firefox_archives.sort(key=os.path.getmtime, reverse=True)
+  newest_build = firefox_archives[0]
+  build_age_seconds = time.time() - os.path.getmtime(newest_build)
+  build_age_days = datetime.timedelta(seconds=build_age_seconds).days
 
-  downloader.download()
-  print 'Downloaded %s' % firefox_archive
+  return newest_build, build_age_days
 
-  # Extract the archive.
-  # TODO(phoglund): implement on win/mac
+
+def _MaybeDownload(target_dir, force):
+  try:
+    downloader = scraper.DailyScraper(directory=target_dir, version=None)
+    filename = downloader.build_filename(downloader.binary)
+    firefox_archive = os.path.join(target_dir, filename)
+
+    if os.path.exists(firefox_archive) and not force:
+      # Touch the file anyway since we were 'successful', so we can accurately
+      # compute the age of the most recent download attempt and act accordingly
+      # when a download fails later.
+      _Touch(firefox_archive)
+      print 'Skipping download as %s is already downloaded.' % firefox_archive
+      return None
+
+    downloader.download()
+    print 'Downloaded %s' % firefox_archive
+    return firefox_archive
+  except scraper.NotFoundException as exception:
+    print 'Failed to download firefox: %s.' % exception
+    fallback_build, age_days = _FindFallbackFirefoxBuild(target_dir)
+
+    if not fallback_build:
+      raise Exception('We failed to download Firefox and we have no builds to '
+                      'fall back on; failing...')
+    if age_days > 3:
+      raise Exception('We have failed to download firefox builds for more '
+                      'than 3 days now: failing so someone looks at it. The '
+                      'most recent build we have is %d days old.' % age_days)
+
+    print 'Using %s instead; it is %d days old.' % (fallback_build, age_days)
+    return fallback_build
+
+
+def _ExtractArchive(firefox_archive, target_dir):
+  # TODO(phoglund): implement on win/mac. See http://crbug.com/454303.
   if sys.platform == 'darwin':
-    print "Temporarily disabled on mac..."
+    print "Disabled on mac..."
     return 0
     volume = '/Volumes/Nightly'
     firefox_executable = '%s/FirefoxNightly.app' % target_dir
@@ -69,7 +95,7 @@
     tar_archive = tarfile.open(firefox_archive, 'r:bz2')
     tar_archive.extractall(path=target_dir)
   elif sys.platform == 'win32':
-    print "Temporarily disabled on win..."
+    print "Disabled on win..."
     return 0
     zip_archive = zipfile.ZipFile(firefox_archive)
     zip_archive.extractall(path=target_dir)
@@ -76,9 +102,31 @@
   else:
     print >> sys.stderr, 'Unsupported platform: %s' % sys.platform
     return 1
-  
+
   print 'Extracted %s' % firefox_archive
   return 0
 
+
+def main():
+  usage = 'usage: %prog -t <target_dir>'
+  parser = OptionParser(usage)
+  parser.add_option('-t', '--target-dir',
+                    help=('Target directory to put the downloaded and extracted'
+                          ' folder with the Firefox Nightly build in.'))
+  parser.add_option('-f', '--force', action='store_true',
+                    help=('Force download even if the current nightly is '
+                          'already downloaded.'))
+  options, _args = parser.parse_args()
+  if not options.target_dir:
+    parser.error('You must specify the target directory.')
+
+  target_dir = options.target_dir
+  if not os.path.isdir(target_dir):
+    os.mkdir(target_dir)
+
+  firefox_archive = _MaybeDownload(target_dir, options.force)
+  if firefox_archive:
+    return _ExtractArchive(firefox_archive, target_dir)
+
 if __name__ == '__main__':
   sys.exit(main())