My blog_title_here

Music collection updates feed via musicbrainz and last.fm

Naturally, subscribing to something like an unfiltered flow of new music releases isn't an option, but no music site other than last.fm out there knows the acts in my collection to track updates for those, and last.fm doesn't seem to have the functionality I need - just to list new studio releases from the artists I listened to beyond some reasonable threshold, or I just haven't been able to find it.

First one seemed easier, but not as entertaining as the second, plus I have virtually no knowledge to pick a site which will be best-suited for that (and I'd hate to pick a first thing from the google), and I'd probably have to post-process what this site feeds me anyway. I've decided to stick with the second way.

Object-db to a web content is a typical task for a web framework, so I chose to use django as a basic template for the task.

The next task is to compare two lists to drop the stuff I already have (local albums list) from the fetched list.

After that comes db storage, and there's not much to implement but a simple ORM-model definition with a few unique keys and the django will take care of the rest.

The last part is the data representation.

One more thing I've thought of is the caching - no need to strain free databases with redundant queries, so the only non-cached data from these are the lists of the releases which should be updated from time to time, the rest can be kept in a single "seen" set of id's, so it'd be immediately obvious if the release was processed and queried before and is of no more interest now.

To summarize: the tools are django, python-musicbrainz2 and pylast; last.fm and musicbrainz - the data sources (although I might extend this list); direct result - this feed.

Exherbo / paludis fossil syncer

Repository, syncer and some instructions are here.

Thought I'd give google some keywords, should someone be looking for the same thing, although I'd probably try to push it into paludis and/or "unavailable" repo, when (and if) I'll get a bit more solid grasp on exherbo concepts.

LUKS + dm-crypt rootfs without password via smartcard

I don't believe in fairly common practice of "trying out" something new on a VM - it just don't work for me, probably because I see it as a stupid and posintless thing on some subconscious level, so I've decided to put it onto one of my two laptops, which kinda needed a good cleanup anyway.

While at it, I thought it'd be a good idea to finally dump that stupid practice of entering fs-password on boot, yet I did like the idea of encrypted fs, especially in case of laptop, so I've needed to devise reasonably secure yet paswordless boot method.

I use in-kernel LUKS-enabled dm-crypt (with the help of cryptsetup tool), and I need some initrd (or init-fs) for LVM-root anyway.

Boot sequence comes down to these:

• Mount pseudofs like proc/sys, get encrypted partition dev and real-rootfs signature (for findfs tool, like label or uuid) from cmdline.
• Init openct, find smartcard in /sys by hardcoded product id and attach it to openct.
• Mount persistent key-material storage (same /boot in my case).
• Read "old" key, replace it with a hashed version, aka "new key".
• Sign old key using smartcard, open fs with the resulting key.
• Drop this key from LUKS storage, add a signed "new" key to it.
• Kill openct processes, effectively severing link with smartcard.
• Detect and activate LVM volume groups.
• Find (findfs) and mount rootfs among currently-available partitions.
• Umount proc/sys, pivot_root, chroot.
• Here comes the target OS' init.

Took me some time to assemble and test this stuff, although it was fun playing with linux+busybox mini-OS. Makes me somewhat wonder about what takes several GiBs of space in a full-fledged OS when BB contains pretty much everything in less than one MiB ;)

And it's probably a good idea to put some early check of /boot partition (hashes, mounts, whatever) into booted OS init-scripts to see if it was not altered in any significant way. Not really a guarantee that something nasty weren't done to it (and then cleaned up, for example) plus there's no proof that actual OS was booted up from it and the kernel isn't tainted in some malicious way, but should be enough against some lame tampering or pranks, should these ever happen.

Anyway, here's the repo with all the initrd stuff, should anyone need it.

Thoughts on VCS, supporting documentation and Fossil

Git is a great help in these tasks, but what I feel lacking there is a first - common timeline (spanning both into the past and the future) for all these data series, and second - documentation.

Solution to the first one I've yet to find.

Documentation for anything more than local implementation details and it's history is virtually non-existant and most times it takes a lot of effort and time to retrace the original line of thought, reasoning and purpose behind the stuff I've done (and why I've done it like that) in the past, often with the considerable gaps and eventual re-invention of the wheels and pitfalls I've already done, due to faulty biological memory.

So, today I've decided to scour over the available project and task management software to find something that ties the vcs repositories and their logs with the future tickets and some sort of expanded notes, where needed.

It just looks like a completely wrong approach for my task, yet I thought that I can probably tolerate that if there are no better options and then I've stumbled upon Fossil VCS.

Fossil's overall design principles and concepts (plus this) are well-documented on it's site (which is a just a fossil repo itself), and the catch-points for me were:

• Tickets and wiki, of course. Can be edited locally, synced, distributed, have local settings and appearance, based on tcl-ish domain-specific language.
• Distributed nature, yet rational position of authors on centralization and synchronization topic.
• All-in-one-static-binary approach! Installing hundreds of git binaries to every freebsd-to-debian-based system, was a pain, plus I've ended up with 1.4-1.7 version span and some features (like "add -p") depend on a whole lot of stuff there, like perl and damn lot of it's modules. Unix-way is cool, but that's really more portable and distributed-way-friendly.
• Repository in a single package, and not just a binary blob, but a freely-browsable sqlite db. It certainly is a hell lot more convenient than path with over nine thousand blobs with sha1-names, even if the actual artifact-storage here is built basically the same way. And the performance should be actually better than the fs - with just index-selects BTree-based sqlite is as fast as filesystem, but keeping different indexes on fs is by sym-/hardlinking, and that's a pain that is never done right on fs.
• As simple as possible internal blobs' format.
• Actual symbolics and terminology. Git is a faceless tool, Fossil have some sort of a style, and that's nice ;)

Yet there are some things I don't like about it:

• HTTP-only sync. In what kind of twisted world that can be better than ssh+pam or direct access? Can be fixed with a wrapper, I guess, but really, wtf...
• SQLite container around generic artifact storage. Artifacts are pure data with a single sha1sum-key for it, and that is simple, solid and easy to work with anytime, but wrapped into sqlite db it suddenly depends on this db format, libs, command-line tool or language bindings, etc. All the other tables can be rebuilt just from these blobs, so they should be as accessible as possible, but I guess that'd violate whole single-file design concept and would require a lot of separate management code, a pity.

But that's nothing more than a few hours' tour of the docs and basic hello-world tests, guess it all will look different after I'll use it for a while, which I'm intend to do right now. In the worst case it's just a distributed issue tracker + wiki with cli interface and great versioning support in one-file package (including webserver) which is more than I can say about trac, anyway.

Availability stats (and history log) with relational database (postgresql)

CREATE TABLE state_hoard.list_http_availability (
 id serial NOT NULL,
 target character varying(128) NOT NULL,
 "domain" character varying(128) NOT NULL,
 check_type state_hoard.check_type NOT NULL,
 "timestamp" numeric,
 source character varying(16),
 CONSTRAINT state_ha__id PRIMARY KEY (id),
 CONSTRAINT state_ha__domain_ip_check_type
 UNIQUE (target, domain, check_type) );

It should probably be extended with other checks later on so there's check_type field with enum like this:

CREATE TYPE state_hoard.check_type AS ENUM ('http', 'https');

Target (IP) and domain (hostname) are separate fields here, since dns data is not to be trusted but the http request should have host-field to be processed correctly.

Resulting table:

CREATE OR REPLACE FUNCTION state_hoard.list_ha_replace()
 RETURNS trigger AS
$BODY$
DECLARE
 updated integer;

BEGIN

-- Implicit timestamping
NEW.timestamp := COALESCE( NEW.timestamp,
 EXTRACT('epoch' FROM CURRENT_TIMESTAMP) );

UPDATE state_hoard.list_http_availability
 SET timestamp = NEW.timestamp, source = NEW.source
 WHERE domain = NEW.domain
 AND target = NEW.target
 AND check_type = NEW.check_type;

-- Check if the row still need to be inserted
GET DIAGNOSTICS updated = ROW_COUNT;
IF updated = 0
THEN RETURN NEW;
ELSE RETURN NULL;
END IF;

END;
$BODY$
 LANGUAGE 'plpgsql' VOLATILE
 COST 100;


CREATE TRIGGER list_ha__replace
 BEFORE INSERT
 ON state_hoard.list_http_availability
 FOR EACH ROW
 EXECUTE PROCEDURE state_hoard.list_ha_replace();

From there I had two ideas on how to use this data and store immediate results, from the poller perspective:

• To replicate the whole table into some sort of "check-list", filling fields there as the data arrives.
• To create persistent linked tables with polled data, which just replaced (on unique-domain basis) with each new poll.

While former looks appealing since it allows to keep state in DB, not the poller, latter provides persistent availability/delay tables and that's one of the things I need.

CREATE TABLE state_hoard.state_http_availability (
 check_id integer NOT NULL,
 host character varying(32) NOT NULL,
 code integer,
 "timestamp" numeric,
 CONSTRAINT state_ha__check_host PRIMARY KEY (check_id, host),
 CONSTRAINT state_http_availability_check_id_fkey FOREIGN KEY (check_id)
 REFERENCES state_hoard.list_http_availability (id) MATCH SIMPLE
 ON UPDATE RESTRICT ON DELETE CASCADE );

CREATE TABLE state_hoard.state_http_delay (
 check_id integer NOT NULL,
 host character varying(32) NOT NULL,
 delay numeric,
 "timestamp" numeric,
 CONSTRAINT state_http_delay_check_id_fkey FOREIGN KEY (check_id)
 REFERENCES state_hoard.list_http_availability (id) MATCH SIMPLE
 ON UPDATE NO ACTION ON DELETE CASCADE );

CREATE OR REPLACE FUNCTION state_hoard.state_ha_replace()
 RETURNS trigger AS
$BODY$
BEGIN

-- Drop old record, if any
DELETE FROM state_hoard.state_http_availability WHERE check_id = NEW.check_id AND host = NEW.host;

-- Implicit timestamp setting, if it's omitted
NEW.timestamp := COALESCE(NEW.timestamp, EXTRACT('epoch' FROM CURRENT_TIMESTAMP));

RETURN NEW;

END;
$BODY$
 LANGUAGE 'plpgsql' VOLATILE
 COST 100;

CREATE TRIGGER state_ha__replace
 BEFORE INSERT
 ON state_hoard.state_http_availability
 FOR EACH ROW
 EXECUTE PROCEDURE state_hoard.state_ha_replace();

CREATE OR REPLACE FUNCTION state_hoard.state_hd_insert()
 RETURNS trigger AS
$BODY$
BEGIN

-- Implicit timestamp setting, if it's omitted
NEW.timestamp := COALESCE( NEW.timestamp,
 EXTRACT('epoch' FROM CURRENT_TIMESTAMP) );

RETURN NEW;

END;
$BODY$
 LANGUAGE 'plpgsql' VOLATILE
 COST 100;


CREATE TRIGGER state_hd__insert
 BEFORE INSERT
 ON state_hoard.state_http_delay
 FOR EACH ROW
 EXECUTE PROCEDURE state_hoard.state_hd_insert();

After that comes the logging part, and the logged part is http response codes.

CREATE TABLE state_hoard.log_http_availability (
 "domain" character varying(128) NOT NULL,
 code integer,
 "timestamp" numeric NOT NULL,
 CONSTRAINT log_ha__domain_timestamp PRIMARY KEY (domain, "timestamp") );

Interval for these averages can be acquired via simple rounding, and it's convenient to have single function for that, plus the step in retriveable form. "Immutable" type here means that the results will be cached for each set of parameters.

CREATE OR REPLACE FUNCTION state_hoard.log_ha_step()
 RETURNS integer AS
'SELECT 600;'
 LANGUAGE 'sql' IMMUTABLE
 COST 100;

CREATE OR REPLACE FUNCTION state_hoard.log_ha_discrete_time(numeric)
 RETURNS numeric AS
'SELECT (div($1, state_hoard.log_ha_step()::numeric) + 1) * state_hoard.log_ha_step();'
 LANGUAGE 'sql' IMMUTABLE
 COST 100;

CREATE OR REPLACE FUNCTION state_hoard.log_ha_coerce()
 RETURNS trigger AS
$BODY$
DECLARE
 updated integer;

BEGIN

-- Implicit timestamp setting, if it's omitted
NEW.timestamp := state_hoard.log_ha_discrete_time(
 COALESCE( NEW.timestamp,
 EXTRACT('epoch' FROM CURRENT_TIMESTAMP) )::numeric );

IF NEW.code = 200
THEN
 -- Successful probe overrides (probably random) errors
 UPDATE state_hoard.log_http_availability
 SET code = NEW.code
 WHERE domain = NEW.domain AND timestamp = NEW.timestamp;
 GET DIAGNOSTICS updated = ROW_COUNT;

ELSE
 -- Errors don't override anything
 SELECT COUNT(*)
 FROM state_hoard.log_http_availability
 WHERE domain = NEW.domain AND timestamp = NEW.timestamp
 INTO updated;

END IF;

-- True for first value in a new interval
IF updated = 0
THEN RETURN NEW;
ELSE RETURN NULL;
END IF;

END;
$BODY$
 LANGUAGE 'plpgsql' VOLATILE
 COST 100;


CREATE TRIGGER log_ha__coerce
 BEFORE INSERT
 ON state_hoard.log_http_availability
 FOR EACH ROW
   EXECUTE PROCEDURE state_hoard.log_ha_coerce();

The only thing left at this point is to actually tie this intermediate log-table with the state-table, and after-insert/update hooks are good place for that.

CREATE OR REPLACE FUNCTION state_hoard.state_ha_log()
 RETURNS trigger AS
$BODY$

DECLARE
 domain_var character varying (128);
 code_var integer;

 -- Timestamp of the log entry, explicit to get the older one, checking for random errors
 ts numeric := state_hoard.log_ha_discrete_time(EXTRACT('epoch' FROM CURRENT_TIMESTAMP));

BEGIN

SELECT domain FROM state_hoard.list_http_availability
 WHERE id = NEW.check_id INTO domain_var;

SELECT code FROM state_hoard.log_http_availability
 WHERE domain = domain_var AND timestamp = ts
 INTO code_var;

-- This actually replaces older entry, see log_ha_coerce hook
INSERT INTO state_hoard.log_http_availability (domain, code, timestamp)
 VALUES (domain_var, NEW.code, ts);

-- Random errors' trapping
IF code_var != NEW.code AND (NEW.code > 400 OR code_var > 400) THEN
 code_var = CASE WHEN NEW.code > 400 THEN NEW.code ELSE code_var END;
 INSERT INTO state_hoard.log_http_random_errors (domain, code)
 VALUES (domain_var, code_var);
END IF;

RETURN NULL;

END;
$BODY$
 LANGUAGE 'plpgsql' VOLATILE
 COST 100;


CREATE TRIGGER state_ha__log_insert
 AFTER INSERT
 ON state_hoard.state_http_availability
 FOR EACH ROW
 EXECUTE PROCEDURE state_hoard.state_ha_log();

CREATE TRIGGER state_ha__log_update
 AFTER UPDATE
 ON state_hoard.state_http_availability
 FOR EACH ROW
 EXECUTE PROCEDURE state_hoard.state_ha_log();

From here, the log will get populated already, but in a few days it will get millions of entries and counting, so it have to be aggregated and the most efficient method for this sort of data seem to be in keeping just change-points for return codes since they're quite rare.

"Random errors" are trapped here as well and stored to the separate table. They aren't frequent, so no other action is taken there.

The log-diff table is just that - code changes. "code_prev" field is here for convenience, since I needed to get if there were any changes for a given period, so the rows there would give complete picture.

CREATE TABLE state_hoard.log_http_availability_diff (
 "domain" character varying(128) NOT NULL,
 code integer,
 code_prev integer,
 "timestamp" numeric NOT NULL,
 CONSTRAINT log_had__domain_timestamp PRIMARY KEY (domain, "timestamp") );

Updates to this table happen on cron-basis and generated right inside the db, thanks to plpgsql for that.

LOCK TABLE log_http_availability_diff IN EXCLUSIVE MODE;
LOCK TABLE log_http_availability IN EXCLUSIVE MODE;

INSERT INTO log_http_availability_diff
 SELECT * FROM log_ha_diff_for_period(NULL, NULL)
 AS data(domain character varying, code int, code_prev int, timestamp numeric);

TRUNCATE TABLE log_http_availability;

And the diff-generation code:

CREATE OR REPLACE FUNCTION state_hoard.log_ha_diff_for_period(ts_min numeric, ts_max numeric)
 RETURNS SETOF record AS
$BODY$

DECLARE
 rec state_hoard.log_http_availability%rowtype;
 rec_next state_hoard.log_http_availability%rowtype;
 rec_diff state_hoard.log_http_availability_diff%rowtype;

BEGIN

FOR rec_next IN
 EXECUTE 'SELECT domain, code, timestamp
 FROM state_hoard.log_http_availability'
 || CASE WHEN NOT (ts_min IS NULL AND ts_max IS NULL) THEN
 ' WHERE timestamp BETWEEN '||ts_min||' AND '||ts_max ELSE '' END ||
 ' ORDER BY domain, timestamp'
LOOP

 IF NOT rec_diff.domain IS NULL AND rec_diff.domain != rec_next.domain THEN
 -- Last record for this domain - skip unknown vals and code change check
 rec_diff.domain = NULL;
 END IF;

 IF NOT rec_diff.domain IS NULL

 THEN
 -- Time-skip (unknown values) addition
 rec_diff.timestamp = state_hoard.log_ha_discrete_time(rec.timestamp + 1);
 IF rec_diff.timestamp < rec_next.timestamp THEN
 -- Map unknown interval
 rec_diff.code = NULL;
 rec_diff.code_prev = rec.code;
 RETURN NEXT rec_diff;
 END IF;

 -- rec.code here should be affected by unknown-vals as well
 IF rec_diff.code != rec_next.code THEN
 rec_diff.code_prev = rec_diff.code;
 rec_diff.code = rec_next.code;
 rec_diff.timestamp = rec_next.timestamp;
 RETURN NEXT rec_diff;
 END IF;

 ELSE
 -- First record for new domain or whole loop (not returned)
 -- RETURN NEXT rec_next;
 rec_diff.domain = rec_next.domain;

 END IF;

 rec.code = rec_next.code;
 rec.timestamp = rec_next.timestamp;

END LOOP;

END;

$BODY$
 LANGUAGE 'plpgsql' VOLATILE
 COST 100
 ROWS 1000;

Auto-away for pidgin

Well, good thing is that pidgin's mature enough to have dbus interface, so as the most problems in life, this one can be solved with python ;)

All there is...

Get idle time:

def get_idle():
  proc = Popen(['xprintidle'], stdout=PIPE)
  idle = int(proc.stdout.read().strip()) // 1000
  proc.wait()
  return idle

Simple dbus client code:

pidgin = dbus.SessionBus().get_object(
  'im.pidgin.purple.PurpleService', '/im/pidgin/purple/PurpleObject' )
iface = dbus.Interface(pidgin, 'im.pidgin.purple.PurpleInterface')

Get initial (available) status:

st = iface.PurpleSavedstatusGetCurrent()
st_type = iface.PurpleSavedstatusGetType(st)
st_msg = iface.PurpleSavedstatusGetMessage(st)

Create away/na statuses:

st_away = iface.PurpleSavedstatusNew('', status.away)
iface.PurpleSavedstatusSetMessage(
  st_away, 'AFK (>{0}m)'.format(optz.away // 60) )
st_na = iface.PurpleSavedstatusNew('', status.xaway)
iface.PurpleSavedstatusSetMessage(
  st_na, 'AFK for quite a while (>{0}m)'.format(optz.na // 60) )

And the main loop:

while True:
  idle = get_idle()
  if idle > optz.away:
    if idle > optz.na:
      iface.PurpleSavedstatusActivate(st_na)
      log.debug('Switched status to N/A (idle: {0})'.format(idle//60))
    else:
      iface.PurpleSavedstatusActivate(st_away)
      log.debug('Switched status to away (idle: {0})'.format(idle//60))
    sleep(optz.poll)
  else:
    if iface.PurpleSavedstatusGetType(
        iface.PurpleSavedstatusGetCurrent() ) in (status.away, status.xaway):
      iface.PurpleSavedstatusActivate(st)
      log.debug('Restored original status (idle: {0})'.format(idle//60))
    sleep(optz.away)

Bonus of such approach is that any other checks can be easily added - fullscreen-video-status, for example, or emacs-dont-disturb status. I bet there are other plugins for this purposes, but I'd prefer few lines of clean py to some buggy .so anytime ;)

Here's the full code.

Single-instance daemon or "invisible dock"

• Mouse-user-friendly
• Look cool (cairo-dock, kiba-dock, macosx)
• Provide control over the launched instances of each app

But it's not really a "dock", since it's actually invisible and basically is just a wrapper for launched commands to check if last process spawned by identical command exists and just bring it to foreground in this case.

#!/usr/bin/env python
# -*- coding: utf-8 -*-

dbus_iface = 'net.fraggod.SID'
dbus_path = '/net/fraggod/SID'

import os, sys, dbus
sid = dbus.SessionBus().get_object(dbus_iface, dbus_path)

if sys.argv[1][0] != '/':
    for path in os.getenv('PATH').split(os.pathsep):
        path = os.path.join(path, sys.argv[1])
        if os.path.exists(path):
            sys.argv[1] = path
            break

sid.instance_request(sys.argv[1:], dict(os.environ))

And that's it, most of these just resolves binary location via PATH so it can be used as unique-index in daemon process right off the pipe.

Daemonized part of the scheme just takes the instance off it's stack, fires up a new one or returs back some error message:

@dbus.service.method( dbus_iface,
    in_signature='asa{ss}', out_signature='s' )
def instance_request(self, argz, env):
    try:
        data = self.pop_instance(argz, env)
        return data if data else ''
    except Exception, err: return 'ERROR: {0}'.format(err)

def pop_instance(self, argz, env):
    ps = argz[0]
    log.info('InstanceRequest: {0}'.format(argz))
    if ps[0] != '/': raise TypeError, 'App path must be absolute'
    ps = os.path.realpath(ps)
    log.debug('Pulling out "{0}"'.format(ps))
    try:
        app = self.apps[ps]
        log.debug('App "{0}" exists, pulling to fg'.format(ps))
        app.show()
    except KeyError:
        log.debug('No app "{0}", starting'.format(ps))
        self.apps[ps] = AppInstance(argz, env, self.log)
        return 'Started'

Dead apps are collected on SIGCHLD and some extra precautions should be taken for the case when the signal arrives during the collector code execution, like when several apps die simultaneously:

def reap_apps(self, sig, frm):
    log.debug('Got app exit signal')
    try:
        locked = self.lock.acquire(False)
        self.lock_req = True # indicates that apps have to be re-checked
        if not locked:
            log.debug('Reap is in progress, re-check scheduled')
            return

        while self.lock_req:
            self.lock_req = False
            log.debug('Reaping dead apps')
            for k,app in self.apps.iteritems():
                if app.dead:
                    del self.apps[k]
                    log.debug('App "{0}" was released'.format(k))

    finally:
        if locked: self.lock.release()
        global loop_interrupt
        loop_interrupt = True
        log.debug('Reaper done')

That way, collector should run until signals stop arriving and shouldn't miss any app under any circumstances.

AppInstance objects incapsulate all operations concerning each app from starting it to focus and waitpid:

class AppInstance(object):
    _id = None # for debugging purposes only
    _ps = _win = None

    def __init__(self, argz, env, logfile=False):
        log.debug('Creating instance with argz: {0}'.format(argz))
        self._id = argz[0]
        self._ps = exe.proc( *argz,
            preexec_fn=os.setsid, env=env,
            stdout=logfile, stderr=exe.STDOUT, stdin=False )

    def show(self):
        if self.windows:
            for win in self.windows: win.focus()
        else: log.debug('No window for app "{0}"'.format(self._id))

    @property
    def windows(self):
        if self._win is None:
            self._win = wm.Window.by_pid(self._ps.pid)
            if self._win: self._win = list(self._win) # all windows for pid
            else: self._win = False
        return self._win

    @property
    def dead(self):
        return self._ps.wait(0) is not None

WM ops here are from fgc package.

To make dbus aware of the service, short note should be put to "/usr/share/dbus-1/services/net.fraggod.SID.service" with path to daemon binary:

[D-BUS Service]
Name=net.fraggod.SID
Exec=/usr/libexec/sid

...plus the hotkeys rebound from "myapp" to just "sic myapp" and the key-dock is ready.

Works especially well with WMs that can keep app windows' props between launches, so just pressing the relevant keys should launch every app where it belongs with correct window parameters and you won't have to do any WM-related work at all.

Code: sic.py sid.py

What can be more user-friendly than that? Gotta think about it...

snmpd-pyagentx or re-discovery of sf.net

Since I've put some two-day effort into creation of net-snmp snmpd extension and had some free time to report bug in source of this inspiration, thought I might as well save someone trouble of re-inventing the wheel and publish it somewhere, since snmpd extension definitely looks like a black area from python perspective.

I've used sf.net as a project admin before, publishing some crappy php code for hyscar project with pretty much the same reasons in mind, and I didn't like the experience much - cvs for code storage and weird interface are among the reasons I can remember, but I'll gladly take all this criticism back - current interface has by far exceed all my expectations (well, prehaps they were too low in the first place?).

Putting up a full-fledged project page took me (a complete n00b at that) about half an hour, everything being simple and obvious as it is, native-to-me git vcs, and even trac among the (numerous) features. Damn pleasant xp, making you wanna upload something else just for the sake of it ;)

libnotify, notification-daemon shortcomings and my solution

Everyone who uses OSS desktop these days probably seen libnotify magic in action - small popup windows that appear at some corner of the screen, announcing events from other apps.

Solution I came up with is to batch the notification messages into a digests as soon as there are too many of them, displaying such digest pop-ups with some time interval, so I can keep a grip on what's going on just by glancing at these as they arrive, switching my activities if something there is important enough.

One more step to making linux desktop more comfortable. Oh, joy ;)

Listening to music over the 'net with authentication and cache

Having seen people really obsessed with the music, I don't consider myself to be much into it, yet I've managed to accumulate more than 70G of it, and counting. That's probably because I don't like to listen to something on a loop over and over, so, naturally, it's quite a bother to either keep the collection on every machine I use or copy the parts of it just to listen and replace.

The easiest way for me was trusty sshfs - it's got the best authentication, nice performance and encryption off-the-shelf with just one simple command. Problem here is the last aforementioned point - sshfs would generate as much bandwith as possible, caching content only temporarily in volatile RAM.

Persistent caching seem to be quite easy to implement in userspace with either fuse layer over network filesystem or something even simpler (and more hacky), like aufs and inotify, catching IN_OPEN events and pulling files in question to intermediate layer of fs-union.

Setting up tunnel was quite straightforward, although I've put together a simple script to avoid re-typing the whole thing and to make sure there aren't any dead ssh processes laying around.

#!/bin/sh
PID="/tmp/.$(basename $0).$(echo "$1.$2" | md5sum | cut -b-5)"
touch "$PID"
flock -n 3 3<"$PID" || exit 0
exec 3>"$PID"
( flock -n 3 || exit 0
  exec ssh\
   -oControlPath=none\
   -oControlMaster=no\
   -oServerAliveInterval=3\
   -oServerAliveCountMax=5\
   -oConnectTimeout=5\
   -qyTnN $3 -L "$1" "$2" ) &
echo $! >&3
exit 0

That way, ssh process is daemonized right away. Simple locking is also implemented, based on tunnel and ssh destination, so it might be put as a cronjob (just like "ssh_tunnel 2049:127.0.0.1:2049 user@remote") to keep the link alive.

Then I've put a line like this to /etc/exports:

/var/export/leech 127.0.0.1/32(ro,async,no_subtree_check,insecure)

Gotcha was in the fact that it wasn't allowed to mount nfs4 root, so tweaking exports file like this...

/var/export/leech 127.0.0.1/32(ro,async,no_subtree_check,insecure,fsid=0)
/var/export/leech/music 127.0.0.1/32(ro,async,no_subtree_check,insecure,fsid=1)

...and "mount -t nfs4 localhost:/music /mnt/music" actually solved the issue.

Why can't I use one-line exports and why the fuck it's not on the first (or any!) line of manpage escapes me completely, but at least it works now even from remote. Hallelujah.

fstab lines for me were these:

/dev/dump/nfscache /var/fscache ext4 user_xattr
localhost:/music /mnt/music nfs4 ro,nodev,noexec,intr,noauto,user,fsc

First two days got me 800+ megs in cache and from there it was even better bandwidth-wise, so, all-in-all, this nfs circus was worth it.