Make callback plugin an always-on aggregate plugin

This makes it so that one doesn't need to explicitly enable nor replace
the default callback plugin.

1 files changed, 94 insertions, 0 deletions

diff --git a/callback_plugins/failure_summary.py b/callback_plugins/failure_summary.py
new file mode 100644
index 000000000..bcb0123b0
--- /dev/null
+++ b/callback_plugins/failure_summary.py
@@ -0,0 +1,94 @@
+# vim: expandtab:tabstop=4:shiftwidth=4
+'''
+Ansible callback plugin.
+'''
+
+from ansible.plugins.callback import CallbackBase
+from ansible import constants as C
+from ansible.utils.color import stringc
+
+
+class CallbackModule(CallbackBase):
+    '''
+    This callback plugin stores task results and summarizes failures.
+    '''
+
+    CALLBACK_VERSION = 2.0
+    CALLBACK_TYPE = 'aggregate'
+    CALLBACK_NAME = 'failure_summary'
+    CALLBACK_NEEDS_WHITELIST = False
+
+    def __init__(self):
+        super(CallbackModule, self).__init__()
+        self.__failures = []
+
+    def v2_runner_on_failed(self, result, ignore_errors=False):
+        super(CallbackModule, self).v2_runner_on_failed(result, ignore_errors)
+        self.__failures.append(dict(result=result, ignore_errors=ignore_errors))
+
+    def v2_playbook_on_stats(self, stats):
+        super(CallbackModule, self).v2_playbook_on_stats(stats)
+        # TODO: update condition to consider a host var or env var to
+        # enable/disable the summary, so that we can control the output from a
+        # play.
+        if self.__failures:
+            self._print_failure_summary()
+
+    def _print_failure_summary(self):
+        '''Print a summary of failed tasks (including ignored failures).'''
+        self._display.display(u'\nFailure summary:\n')
+
+        # TODO: group failures by host or by task. If grouped by host, it is
+        # easy to see all problems of a given host. If grouped by task, it is
+        # easy to see what hosts needs the same fix.
+
+        width = len(str(len(self.__failures)))
+        initial_indent_format = u'  {{:>{width}}}. '.format(width=width)
+        initial_indent_len = len(initial_indent_format.format(0))
+        subsequent_indent = u' ' * initial_indent_len
+        subsequent_extra_indent = u' ' * (initial_indent_len + 10)
+
+        for i, failure in enumerate(self.__failures, 1):
+            lines = _format_failure(failure)
+            self._display.display(u'\n{}{}'.format(initial_indent_format.format(i), lines[0]))
+            for line in lines[1:]:
+                line = line.replace(u'\n', u'\n' + subsequent_extra_indent)
+                indented = u'{}{}'.format(subsequent_indent, line)
+                self._display.display(indented)
+
+
+# Reason: disable pylint protected-access because we need to access _*
+#         attributes of a task result to implement this method.
+# Status: permanently disabled unless Ansible's API changes.
+# pylint: disable=protected-access
+def _format_failure(failure):
+    '''Return a list of pretty-formatted lines describing a failure, including
+    relevant information about it. Line separators are not included.'''
+    result = failure['result']
+    host = result._host.get_name()
+    play = _get_play(result._task)
+    if play:
+        play = play.get_name()
+    task = result._task.get_name()
+    msg = result._result.get('msg', u'???')
+    rows = (
+        (u'Host', host),
+        (u'Play', play),
+        (u'Task', task),
+        (u'Message', stringc(msg, C.COLOR_ERROR)),
+    )
+    row_format = '{:10}{}'
+    return [row_format.format(header + u':', body) for header, body in rows]
+
+
+# Reason: disable pylint protected-access because we need to access _*
+#         attributes of obj to implement this function.
+#         This is inspired by ansible.playbook.base.Base.dump_me.
+# Status: permanently disabled unless Ansible's API changes.
+# pylint: disable=protected-access
+def _get_play(obj):
+    '''Given a task or block, recursively tries to find its parent play.'''
+    if hasattr(obj, '_play'):
+        return obj._play
+    if getattr(obj, '_parent'):
+        return _get_play(obj._parent)