Remove mid from journal.py

[wesleybowman]

Removed mid variable from JournalHandler since the MESSAGE_ID is already
in the extras variable. MESSAGE_ID was being set to None, but this won't
appear in the logs.

[keszybz]

Looks reasonable, but can you please split the style fixes out as a separate commit from the mid change?

[keszybz]

Yes, I agree that map_priority is a much better name. This part of the code is very old, it even predates the time when python-systemd was in the systemd repo. Hence the style that is a bit strange.

But I think we must keep backwards compatibility here. Can you add mapPriority = map_priority or something like that?

[wesleybowman]

Changed to only be the removal of mid for this PR.

[wesleybowman]

Moved the style fixes and your request for mapPriority over to PR #45

[wesleybowman]

@keszybz rebased on master to fix conflicts

[keszybz]

The idea was that you can set MESSAGE_ID either on the handler (in which case it lands in _extras and is added to all messages through that handler), or on each individual message. With your patch, setting it on the message is not possible any more.

The issue with current code is that if both are specified, we get an error, because MESSAGE_ID would be specified twice. So this should be fixed, but I think the ability to specify MESSAGE_ID on the message should be retained. If both are present, the one from the message should have higher priority, and the one from the handler should be ignored.

[wesleybowman]

If I am understanding correctly, setting it on each individual message is still possible.

Is this an example of setting it on the individual message:
log.warning("Message with ID", extra={'MESSAGE_ID': mid})

and this sets a field for the entire handler:
JournalHandler(SYSLOG_IDENTIFIER='my-cool-app')

If these assumptions are what you are referring to, then this patch will still allow for this.

[keszybz]

Ah, I pushed the wrong branch and github closed the PR. I'll submit a replacement PR.