Initial work on adding a pre_import hook

bugwarrior/README.rst

@@ -86,6 +86,17 @@ Create a ``~/.bugwarriorrc`` file with the following contents.
   #annotation_length = 45
   #description_length = 35
 
+  # Use hooks to run commands prior to importing from bugwarrior-pull.
+  # bugwarrior-pull will run the commands in the order that they are specified
+  # below.
+  #
+  # pre_import: The pre_import hook is invoked after all issues have been pulled
+  # from remote sources, but before they are synced to the TW db. If your
+  # pre_import script has a non-zero exit code, the `bugwarrior-pull` command will
+  # exit early.
+  [hooks]
+  pre_import = /home/someuser/backup.sh, /home/someuser/sometask.sh
+
   # This section is for configuring notifications when bugwarrior-pull runs,
   # and when issues are created, updated, or deleted by bugwarrior-pull.
   # Three backend are currently suported:

bugwarrior/db.py

@@ -3,6 +3,7 @@
 import os
 import re
 import warnings
+import subprocess
 
 import bitlyapi
 import dogpile.cache
@@ -328,6 +329,18 @@ def _bool_option(section, option, default):
         'changed': [],
         'closed': get_managed_task_uuids(tw, key_list, legacy_matching),
     }
+
+    # Before running CRUD operations, call the pre_import hook(s).
+    if conf.has_option('hooks', 'pre_import'):
+        pre_import = [t.strip() for t in conf.get('hooks', 'pre_import').split(',')]
+        if pre_import is not None:
+            for hook in pre_import:
+                exit_code = subprocess.call(hook, shell=True)
+                if exit_code is not 0:
+                    log.name('hooks:pre_import').error(
+                            'Non-zero exit code %d on hook %s' % (exit_code, hook))
+                    sys.exit(1)
+
     for issue in issue_generator:
         if isinstance(issue, tuple) and issue[0] == ABORT_PROCESSING:
             raise RuntimeError(issue[1])