automate new logging system

[zooko]

There is a nice new logging tool in foolscap 0.2.2 which we use in tahoe 0.7.0.

Unfortunately the way to use it currently requires a couple of manual steps:

1. pass FLOGFILE=flog.pickle.bz2 and FLOGTWISTED=1 environment variables to the tahoe process

2. find the resulting flog.pickle.bz2 file (in your ~/.tahoe directory)

3. run flogtool dump flog.pickle.bz2 on it to get a text output

3.b. alternately, run flogtool web-viewer flog.pickle.bz2 on it to get a nice HTML view with indentation and coloration

We should probably spend some time trying to automate or at least document this process so that people who use tahoe v0.7.0 will have good logging.

[zooko]

Actually I think the current logging system already works. I need to double-check this.

[warner]

updated to use FLOGFILE= and to use .bz2-compressed event pickles.

The intention for production nodes is to use the "log gatherer" feature to automatically send all log events to the central gatherer.

Eventually, my plan is to have one logfile to which major events are written, and then have minor events only get written (to the pickle) when things go wrong. But we're only halfway there, and I fear that we've got the wrong half done so far, resulting in fewer log messages recorded rather than too many.

[warner]

oops, update description again.

Also note that the FLOGFILE= and FLOGTWISTED= environment variables are mainly intended to get foolscap log events recorded during unit tests. But they're still useful for actual application runs until I make the same functionality available to the tahoe startup code. At that point, the node will initialize foolscap logging itself, rather than requiring this environment-variable end-run.