Filtering by source (-s)

[stuartpb]

Per heroku:

 -s, --source SOURCE  # only display logs from the given source

This kind of depends on sorting out how we'll even do sources - I believe heroku has "app" and "router".

[stuartpb]

Like the discussion in #5 about limiting lines, this will almost definitely be handled by a post-hoc grep, with possible hinting-by-parameter to the app-logs hook scripts.

[stuartpb]

Also like #5, this is warranted (at the command level) because it's filtering lines before taking up bandwidth to send them. Offloading it to the client would be bandwidth-cruel (not to mention kinda kludgy).

[stuartpb]

In fact, it could be argued that there's merit for a few more filtering options.