From 1b875b543fa414c0971941b3bb2951e7523035aa Mon Sep 17 00:00:00 2001
From: Ralph Bean <rbean@redhat.com>
Date: Feb 27 2014 14:40:40 +0000
Subject: Add lots of context to fedmsg error emails.


---

diff --git a/roles/fedmsg_base/templates/logging.py.j2 b/roles/fedmsg_base/templates/logging.py.j2
index 7153e9f..1f1ccb8 100644
--- a/roles/fedmsg_base/templates/logging.py.j2
+++ b/roles/fedmsg_base/templates/logging.py.j2
@@ -1,4 +1,88 @@
 # Setup fedmsg logging.
+
+# All of these modules are just used by the ContextInjector below.
+import inspect
+import logging
+import os
+import psutil
+import socket
+import traceback
+
+
+class ContextInjector(logging.Filter):
+    """ Logging filter that adds context to log records.
+
+    Filters are typically used to "filter" log records.  They declare a filter
+    method that can return True or False.  Only records with 'True' will
+    actually be logged.
+
+    Here, we somewhat abuse the concept of a filter.  We always return true,
+    but we use the opportunity to hang important contextual information on the
+    log record to later be used by the logging Formatter.  We don't normally
+    want to see all this stuff in normal log records, but we *do* want to see
+    it when we are emailed error messages.  Seeing an error, but not knowing
+    which host it comes from, is not that useful.
+
+    http://docs.python.org/2/howto/logging-cookbook.html#filters-contextual
+    """
+
+    def filter(self, record):
+        record.host = current_hostname
+        record.proc = current_process
+        record.pid = current_process.pid
+        record.proc_name = current_process.name
+        record.command_line = " ".join(current_process.cmdline)
+        record.callstack = self.format_callstack()
+        return True
+
+    @staticmethod
+    def format_callstack():
+        for i, frame in enumerate(f[0] for f in inspect.stack()):
+            if not '__name__' in frame.f_globals:
+                continue
+            modname = frame.f_globals['__name__'].split('.')[0]
+            if modname != "logging":
+                break
+
+        def _format_frame(frame):
+            return '  File "%s", line %i in %s\n    %s' % (frame)
+
+        stack = traceback.extract_stack()
+        stack = stack[:-i]
+        return "\n".join([_format_frame(frame) for frame in stack])
+
+    @staticmethod
+    def get_current_process():
+        mypid = os.getpid()
+        for proc in psutil.process_iter():
+            if proc.pid == mypid:
+                return proc
+
+        # This should be impossible.
+        raise ValueError("Could not find process %r" % mypid)
+
+
+current_process = ContextInjector.get_current_process()
+current_hostname = socket.gethostname()
+
+hefty_format = """Message
+-------
+[%(asctime)s][%(name)10s %(levelname)7s]
+%(message)s
+
+Process Details
+---------------
+host:     %(host)s
+PID:      %(pid)s
+name:     %(proc_name)s
+command:  %(command_line)s
+
+Callstack that lead to the logging statement
+--------------------------------------------
+%(callstack)s
+"""
+
+
 # See the following for constraints on this format http://bit.ly/Xn1WDn
 config = dict(
     logging=dict(
@@ -8,6 +92,18 @@ config = dict(
                 "datefmt": "%Y-%m-%d %H:%M:%S",
                 "format": "[%(asctime)s][%(name)10s %(levelname)7s] %(message)s"
             },
+            hefty={
+                "datefmt": "%Y-%m-%d %H:%M:%S",
+                "format": hefty_format,
+            },
+        ),
+        filters=dict(
+            context={
+                # This "()" syntax in the stdlib doesn't seem to be documented
+                # anywhere.  I had to read
+                # /usr/lib64/python2.7/logging/config.py to figure it out.
+                "()": ContextInjector,
+            },
         ),
         handlers=dict(
             console={
@@ -18,8 +114,8 @@ config = dict(
             },
             mailer={
                 "class": "logging.handlers.SMTPHandler",
-                # TODO -- potentially change this to a nicer mail formatter.
-                "formatter": "bare",
+                "formatter": "hefty",
+                "filters": ["context"],
                 "level": "ERROR",
                 "mailhost": "bastion.phx2.fedoraproject.org",
                 "fromaddr": "fedmsg@fedoraproject.org",