dstat plugin for showing free disk space

dstat_fsspace.py

# Drop this into /usr/local/share/dstat (or equivalent).
# Use it like so:
#    DSTAT_FSSPACE_MOUNTS=/,/opt dstat --fsspace"
class dstat_plugin(dstat):
    """ Disk use, based on freespace plugin """

    def __init__(self):
        self.nick = ('used', 'free', 'total')
        self.cols = len(self.nick)

    def vars(self):
        mounts = os.getenv('DSTAT_FSSPACE_MOUNTS') or '/'
        mounts = mounts.split(',') or []
        return mounts

    def name(self):
        return ['fs' + name for name in self.vars]

    def extract(self):
        self.val['total'] = (0, 0)
        for name in self.vars:
            try:
                res = os.statvfs(name)
                stats = [
                    res.f_blocks - res.f_bavail,  # used
                    res.f_bavail,                 # free
                    res.f_blocks,                 # total
                ]
                frsize = float(res.f_frsize)
                self.val[name] = list(map(lambda x: x * frsize, stats))
            except Exception as e:
                self.val[name] = [-1] * len(self.nick)