johnsu01@myles:~$ mpc playlist grep -i outro wc -l
14

Half a lifetime ago, somewhere at the end of the last millennia I became a free software enthusiast. On and off, I've been working on Free Software for the past fifteen years - most of them unknown, discontinued by now; a huge part of this work was a hobby: small, infrequent contributions. But it was, and still is, something I enjoy doing, something that satisfies my hunger for knowledge, my desire to give back to the community I received so much from. Over the years, what originally started as a desire became a need. What started as a preference, became a requirement. And all through these years, I had a dream, a clear goal I wanted to achieve, which gave purpose to a lot of things I wrote and worked on.This past Monday, the goal was reached. I left the BalaBit support department this week, and went for greener pastures, to do what I wanted to do since I became a free software fanatic: work on free software for a living. As of July first, I'm officially a syslog-ng OSE developer, working full time on 100% Free Software. And not just any software, but something used by millions all over the world. For the first time in my life, I am able to do what I want, for a living.So how did I end up here?It all started on a boring night in December, 2010, when I wrote the first version of the mongodb destination, which also marks my entrance into the syslog-ng contributor scene (apart from a set of bugfixes I was doing in my role as a software engineer at support). From this grew an agreement between the support and development departments (and myself, of course), that I can spend 20% of my time working on syslog-ng OSE. For a while, I spent my Fridays doing just that, eventually obtaining another hat: maintaining the 3.3 stable branch, and later the 3.4 branch too. Meanwhile, the 20% percent was reconsidered, and became 50%, with the premise that it will become 100% in the not too distant future. That future is now.That future is now, and while there will be a slower ramp-up time, there are great things in store, of which, I'll talk about in a later post. Needless to say, though, even if I achieved a dream, there are other desires to pursue, and I'm not going to spend fifteen years achieving them: it's time to fire up the rocket boots, and see where they take me.Two years. Watch this place.

In light of the recent leaks about the NSA's illegal spying, I've decided to go back to using M-x spook output in my email signatures. cypherpunk anthrax John Kerry rail gun security plutonium Guantanamo wire transfer JPL number key military MD5 SRI FIPS140 Uzbekistan

So I'd previously talked about migrating machines. From having one virtual machine running "mail" + "web" + "stuff" I've now got three hosts:

ssh.steve.org.uk

This is supposed to be used solely for shell access, email reading, IRC. Sadly it still hosts one website, the web interface to my Mercurial repositories. This can't be moved without moving the repositories which is a step too far. Although I don't particularly want people browsing my code/changes I do want them to be able to clone them. If I could get anonymous-SSH checkouts working, sanely, then I'd be happy, but I don't see how to do that.

skx-web

This hosts all my websites except for two. The two that are excluded are my mercurial repositories, which still lives on ssh.steve.org.uk, and my blogspam service.

blogspam

This runs my blogspam.net service. I wish I could retired this, since it uses cruftly XML::RPC. I'd rather see a RESTful application sending/receiving JSON. Sadly I can't kill it without annoying a lot of people. So it must remain.

I chose to add the blogspam guest, because that service does really take over an IP, and it just seemed simplest to move it to one machine. As a quick hack both http://repository.steve.org.uk & http://blogspam.net/ run under Apache. Although the other websites run under their own UID with thttpd + my proxy. Now time to change the subject entirely. I've recently joined gym. Which isn't as horrible as I thought it might be, though as a matter of policy I refuse to go on any of those fancy running/jogging machines. The first three weeks I just alternated between the cycling machines and the rowing machines. Initially ten minutes on each, then twenty, then thirty. Now I'm being all brave and adventurous, using new machines and pieces of equipment. Writing this I've got a dull ache in both my arms, after doing seated-dips with 100Lbs. So I guess I'm starting to make progress. No specific goals in mind, but I've been paying slightly more attention to my diet over the past month and I think if I'm a "little fitter" and have "slightly nicer arms" then I'll be happy enough. I've no desire to go all anal and count calories, or give up chocolate and beer. So it is almost hard to explain why I'm going, but .. it is fun, and watching the numbers change is fun too. I'll probably post more about this in the future.

Yesterday I uploaded a big package and got multiple timeouts. I then figured out that DDs can also upload using SFTP (i.e. SSH s file transfer thingie) instead of traditional FTP, which seems like a more modern alternative. So let s give that a try. With dput-ng, the following configuration leads to using sftp by default:

mkdir -p ~/.dput.d/profiles/
cat > ~/.dput.d/profiles/ftp-master.json <<EOT
 
    "fqdn": "ssh.upload.debian.org",
    "incoming": "/srv/upload.debian.org/UploadQueue/",
    "method": "sftp"
 
EOT

Note that uploading via SFTP will lead to debianqueued uploading the files via FTP for you. But maybe that is more reliable than doing it yourself. We ll see :-).

As part of writing a new mail client I'm wondering about how to change my email-life, and how other people process/handle their incoming email. I sort my incoming email into folders at delivery-time using procmail. Mail is generally filtered into mailboxes on the basis of the company that sent it, the person that sent it, or the machine which generated it. Because I manage a lot of machines personally I've split things up so that I have a folder per host. So on a morning I might have unread mail in the following folders:

machines.steve.org.uk/
machines.da-db1/
machines.da-db2/
machines.da-web1/
machines.da-web2/
machines.da-web3/
machines.da-web4/

The per-machine mailboxes usually contain a single mail every day from LogWatch, along with output from any cron-jobs. For example today I received the mail:

From: Cron Daemon
To: steve@steve.org.uk
Subject: Cron steve@steve.org.uk /home/steve/bin/download-check
URL http://nodejs.org/ - no longer matches v0.10.9

Generally speaking I don't need to read the per-machine messages. I'll keep the most recent 100 for reference, but only need to look if something seems "off" on a machine. But if I don't look I'd not see the node upgrade notice, so find that I do read them after all. This suggest to me that email isn't the right way to handle this kind of thing. Instead I should use a notification system - at work we have a central service called MauveAlert (yes, Red Dwarf reference). Mauve receives "alerts" of various kinds, via UDP. The alerts are then fanned out to appropriate people via XMPP, Email, or SMSs. I have a similarly-inspired system I use on my Debian Administration cluster. A (node) service runs non-stop collecting UDP messages and showing them on a dashboard. I look at it throughout the day to see when slaughter runs, etc. Anyway in conslusion I get a lot of mail. Some of it is related to random projects, and all ends up in the steve.org.uk/ mailbox, some of it relates to machines, and gets filed away, and I have regular conversions with folk so I have a .people.kirsi/ folder which receives a lot of attention, for example. ObRandom:daily() - Mark ~/Maildir/.machines.*, etc, read.

I recently made a routine analysis of my kitchen. (Of course I make a routine analysis of my kitchen; don t you?) In it, I discovered these items, still usable, but approaching that magic throw it out date:

• Baby carrots
• Potatoes
• Lemons
• Green beans
• Corn

So, I thought, what can I make that would use all of these? And I realized I had some shrimp in the freezer, so: a shrimp boil! I tossed it all, plus some various seasonings and a few other veggies, into the Dutch oven, and boiled. Jacob and Oliver watched the activity with interest. Well, except for the potato-peeling part. For that, they went and played with their toy school buses. But the rest was good. They carefully observed me adding some spices, some vegetables, the shrimp, and watched it all simmer. Then it was time to eat. Excitement! Of course, it did take a few minutes to boil, so Jacob got down his whiteboard while Oliver looked on. They enjoyed learning how to peel the shell from the shrimp and devoured their food. And another night recently, Jacob unexpectedly showed up in the kitchen at 10PM. He said he was thirsty, so I got him some water. He asked, Dad, did you make ice cream? Earlier that day, I had prepared ice cream with Oliver, but it was a kind that had to be cooked (lemon with pureed strawberries and peaches) and it wasn t cool enough to finish before their bedtime. I did let them help add the ice and salt to the ice cream freezer just before they went to bed. So I told Jacob that yes, the ice cream was done. He stood there, tiredly, considering, with this oh he ll never say yes to ice cream at 10PM look on his face. So I said, would you like one bite right now? The look of delight on his face was amazing; a broad smile, a twinkle in his eyes, and a clap. So I got out the big bowl of ice cream and scooped up one big spoonful. He loved it. Then I said, should we go look at the stars? I carried Jacob outside to the porch. We stood there, looking up. I used to do this with him periodically, but it had been about a year. So he was thrilled. It was a partially overcast night, but there were still some stars visible. He had no idea there were some stars missing. To him, it was amazing and wonderful and infinite. Oh dad, there are way too many stars to count! He stayed there, arms around my neck, for a minute or two, then was ready to go back inside. I set him down, gave him a hug, said Goodnight, Jacob. And off he trotted, back upstairs, wearing a contented smile, and he fell asleep almost immediately. All it takes to delight children is a bit a shrimp or some stars. And those things delight me, too.

PHP 5.5 rc2 was recently uploaded to Debian unstable by Ond ej Sur . Along side the new PHP version and its features the PHP team has dealt with the JSON extension being non-free because of the The Software shall be used for Good, not Evil license (see debian #692613).

php5 (5.5.0~rc1+dfsg-1) experimental; urgency=low
    [...]
  * Add dfsg-repack.sh script to remove non-free JSON module
    (Closes: #692613)
  * Remove php5-json from Provides, since that's no longer true
 -- Ond ej Sur  <ondrej@debian.org>  Fri, 17 May 2013 14:41:41 +0200

A package with a DFSG replacement for the JSON extension is waiting in the NEW queue and should be available soon. The new JSON extension was done by Remi Collet (PHP developer and Fedora s PHP maintainer). Review and patches are welcomed, code is available at https://github.com/remicollet/pecl-json-c . I hope the PHP project will adopt the solution, after claiming they won t fix it themselves (see php.net #63520).
Filed under: Debian GNU/Linux, PHP

I wrote a small wiki page for botch. It includes links to some hopefully useful resources like my FOSDEM 2013 talk or my master thesis about botch. The final goal of botch is to generate a build order with which Debian can be bootstrapped from zero to more than 18000 source packages. But such a build order can only be generated once enough source packages (by now the number is around 70) incorporate build profiles which allow to compile them with less build dependencies and thereby break all build dependency cycles. So an intermediary goal of botch is, to find a "good" (i.e. a close to minimal amount) selection of such build dependencies that should be dropped from their source packages. So far, the results of all heuristics we use for this task were just dumped to standard output. Since this textual format was hard to read for a human developer and even worse machine readable, that tool now outputs its results in JSON. This data is then converted by another tool to a more human readable format. One such format is HTML and with the help of javascript for sortable and pageable tables, the data can then be presented without producing too much visual clutter (at least compared to the initial textual format). Another advantage of HTML is, that the data can now easily be shared with other developers without them having to run botch or install any other program first. So without further ado, please find the result of running our heuristics on Debian Sid as of 2013-01-01 here: http://mister-muffin.de/bootstrap/stats/ Here is a screenshot of what you can expect (you can see part of the table of edges with most cycles through them): As a developer uses this information to add build profiles to source packages, this HTML page can be regenerated and will show which strongly connected components are now left in the graph and how to best make them acyclic as well. Besides other improvements I also updated the data I used to generate the graphs from this post. I found this update to be necessary since we found and fixed several implementation bugs since October 2012, so this new plot should be more accurate. Here a graph which shows the amount of vertices in the biggest strongly connected component of Debian Sid by date. Some datapoints are missing for dates for which important source packages in Sid were not compilable.

On saturday 25. of May I gave a talk about FreedomBox at the "Claim back your device" track of LinuxTag in Berlin. LinuxTag is a fairly big annual conference about (yes, you guessed right) Linux and related topics. The FreedomBox is a project to help non-geeks care about their personal privacy when online, same ways as geeks have practiced for a decade or more. Concrete goal is to design a small, cheap physical box similar to an internet gateway or wifi router but with three additions:

• Easy and intuitive to setup and personalize for non-geeks
• Offers routines to help you protect your privacy
• Offers routines to let you help others in need of privacy

"Privacy" is commonly mistaken as "secrecy": Privacy is to keep you in control of your information, so that sharing or keeping to yourself is truly your own choice. Thanks a lot especially to Matthias Kirschner for inviting me as a speaker! Slides (sources) for the event.

Not so long ago I read Dmitrijs' blog post on how to configure apt-cacher-ng to advertise it's service using avahi. As I normally use my laptop in my home and at work, and both networks have apt-cacher-ng running, I decided to give it a try.

I have been administering apt-cacher-ng for three networks so far, and I really find it a useful tool. Then, thanks to the aforementioned blog post, I discovered squid-deb-proxy. I don't use squid, so it's not for my normal use case, but some people will surely find it interesting.

But I found it's client package to be really interesting. It will discover any service providing _apt_proxy._tcp through avahi and let apt use it. But then the package wasn't available in Debian. So, I contacted Michael Vogt to see if he was interested in putting at least the client in Debian's archive. He took the opportunity to upload the full squid-deb-proxy, so thanks a lot Michael :-)

I then filled a wishlist bug against apt-cacher-ng to provide the avahi configuration for publishing the service, which Eduard included in the last version of it. So thanks a lot Eduard too!

tl;dr
You know only need apt-cacher-ng >= 0.7.13-1 and avahi-daemon installed on your server and your mobile users just need squid-deb-proxy-client. Then the proxy autoconfiguration for apt will just work.

One again, thanks a lot to the respective maintainers for allowing this into Jessie :-)

Gotchas
Yes, there are still some rough edges. On one of the networks I'm behind a proxy. While configuring my machine to use apt-cacher-ng's service as a proxy trough apt.conf, apt-listbugs would just work. But now, using the service as discovered by squid-deb-proxy-client, apt-listbugs just times out. Maybe I need to fill some other bug yet...

In my professional life I am sometimes required to provide technical support to one of our salesmen. I find this an interesting change in pace though sometimes challenging.

Occasionally I fail to clearly convey the solution we are trying to sell because of my tendency to focus on detail the customer probably does not need to understand but I think is the interesting part of the problem.

Conversely sometimes the sales people gloss over important technology choices which have a deeper impact on the overall solution. I was recently in such a situation where as part of a larger project the subject of internationalisation (you can see why it gets abbreviated to i18n) was raised.

I had little direct personal experience with handling this within a project workflow so could not give any guidance but the salesman recommended the Transifex service as he had seen it used before, indicated integration was simple and we moved onto the next topic.

Unfortunately previous experience tells me that sometime in the near future someone is going to ask me hard technical questions about i18n and possibly how to integrate Transifex into their workflow (or at least give a good estimate on the work required).
LearningBeing an engineer I have few coping strategies available for situations when I do not know how something works. The approach I best know how to employ is to give myself a practical crash course and write up what I learned...so I did.

I proceeded to do all the usual things you do when approaching something unfamiliar (wikipedia, google, colleagues etc.) and got a basic understanding of internationalisation and localisation and how they fit together.

This enabled me to understand that the Transifex workflow proposed only covered the translation part of the problem and that, as Aldrich observed in my title quote, there is an awful lot more to translation than I suspected.
PlatformsMy research indicated that there are numerous translation platforms available for both open source and commercial projects and Transifex is one of many solutions.

Although the specific platform used was Transifex most of these observations apply to all these other platforms. The main lesson though is that all platforms are special snowflakes and once a project invests effort and time into one platform it will result in the dreaded lock in. The effort to move to another platform afterwards is at least as great as the initial implementation.

It became apparent to me that all of these services, regardless of their type, boil down to a very simple data structure. They appear to be a trivial table of Key:Language:Value wrapped in a selection of tools to perform format conversions and interfaces to manipulate the data.

There may be facilities to attach additional metadata to the table such as groupings for specific sets of keys (often referred to as resources) or translator hints to provide context but the fundamental operation is common.

The pseudo workflow is:

• Import a set of keys
• Provide a resource grouping for the keys.
• Import any existing translations for these keys.
• Use the services platform to provide additional translations
• Export the resources in the desired languages.

The Transifex service does at least allow for the Key values to be arbitrary although the resources are separated by language.

Even assuming a project uses gettext PO files and UTF-8 character encoding (and please can we kill every other character encoding and move the whole world to UTF-8) the tools to integrate the import/export into the project must be written.

A project must decide some pretty important policies, including:

• Will they use a single service to provide all their translations.
• Will they allow updates to the files in their revision control system and how those will be integrated.
• Will there be a verification step and if so who and how will that be performed. Especially important is the question of a reviewer understanding the translated language being integrated and how that is controlled.
• Will the project be paying for translations
• Will the project allow machine translations, if not can they be used as an initial hint (sometimes useful if the translators are weak in the "default" language

These are project policy decisions and, as I discovered, just as difficult to answer as the technical challenges.

Armed with my basic understanding it was time to move on and see how the transifex platform could be integrated into a real project workflow.
ImplementingProof of conceptMy first exercise was to take a trivial command line tool, use xgettext to generate a PO file and add the relevant libintl calls to produce gettext internationalised tool.

A transifex project was created and the english po file uploaded as the initial resource. A french language was added and the online editor used to provide translations for some strings. The PO resource file for french was exported and the tool executed with LANGUAGE=fr and the french translation seen.

This proved the trivial workflow was straightforward to implement. It also provided insight into the need to automate the process as the manual website operation would soon become exceptionally tedious and error prone.
Something more usefulTo get a better understanding of a real world workflow I needed a project that:

• Already internationalised but had limited language localisation
• Did not directly use gettext
• Had a code base I understood
• Could be modified reasonably easily.
• Might find the result useful rather than it being a purely academic exercise.

I selected the NetSurf web browser as it best fit this list.

Internally NetSurf keeps all the translated messages in a simple associative array this is serialised to an equally straightforward file named FatMessages. The file is UTF-8 encoded with keys separated from values by a colon. The Key is constrained to be ASCII characters with no colons and is structured as language.toolkit.identifier and is unique on identifier part alone.

This file is processed at build time into a simple identifier:value dictionary for each language and toolkit.

Transifex can import several resource formats similar to this, after experimenting with YAML and Android Resource format I immediately discovered a problem, the services import and export routines were somewhat buggy.

These routines coped ok with simple use cases but having more complex characters such as angle brackets and quotation marks in the translated strings would completely defeat the escaping mechanisms employed by both these formats (through entity escaping in android resource format XML is problematic anyway)

Finally the Java property file format was used (with UTF-8 encoding) which while having bugs in the import and export escaping these could at least be worked around. The existing tool that was used to process the FatMessages file was rewritten to cope with generating different output formats and a second tool to merge the java property format resources.

To create these two tools I enlisted the assistance of my colleague Vivek Dasmohapatra as his Perl language skills exceeded my own. He eventually managed to overcome the format translation issues and produce correct input and output.

I used the Transifex platforms free open source product, created a new project and configured it for free machine translation from the Microsoft service, all of which is pretty clearly documented by Transifex.

Once this was done the messages file was split up tinto resources for the supported languages and uploaded to the transifex system.

I manually marked all the uploaded translations as "verified" and then added a few machine translations to a couple of languages. I also created spanish as a new language and machine translated most of the keys.

The resources for each language were then downloaded and merged and the resulting FatMessages file checked for differences and verified only the changes I expected appeared.

I quickly determined that manually downloading the language resources every time was not going to work with any form of automation, so I wrote a perl script to retrieve the resources automatically (might be useful for other projects too).

Once these tools were written and integrated into the build system I could finally make an evaluation as to how successful this exercise had been.
ConclusionsThe main things I learned from this investigation were:

• Internationalisation has a number of complex areas
• Localisation to a specific locale is more than a mechanical process.
• The majority of platforms and services are oriented around textural language translation
• There is a concentration on the gettext mode of operation in many platforms
• Integration to any of these platforms requires both workflow and technical changes.
• At best tools to integrate existing resources into the selected platform need to be created
• Many project will require format conversion tools, necessitating additional developer time to create.
• The social issues within an open source project may require compromise on the workflow.
• The external platform may offer little benefits beyond a pretty user interface.
• External platforms introduce an external dependency unless the project is prepared and able to run its own platform instance.
• Real people are still required to do the translations and verify them.

after the release is before the release. this week I started to pick up my RC bug squashing activities again. first results:

• #675231 psad: "psad: prompting due to modified conffiles which were not modified by the user"
  add a comment to the bug report
• #700527 libjs-jquery: ""libjs-jquery broken by movabletype-opensource << 5.1.4+dfsg-3~""
  upload to DELAYED/2 with patch (adding Conflicts) prepared by a fellow DD, then uploaded by maintainer
• #706764 assaultcube-data: "assaultcube-data: fails to upgrade from squeeze - trying to overwrite /usr/share/man/man6/assaultcube-server.6.gz"
  add Breaks/Replaces as suggested in the bug report, upload to DELAYED/2
• #707686 dhelp: "dhelp: FTBFS and uninstallable in sid: needs ruby-gettext"
  file new bug with patch

besides that I've also started to look at the "FTBFS with perl 5.18 in experimental" bugs which are not RC yet. yes, perl 5.18 is already in experimental!

There was an interesting question by Fool recently on the StackExchange site for Boardgames: How do you play a game like Rock-Paper-Scissors with friends online? Or any other game where players have to simultaneously submit their moves (e.g. Diplomacy, or Rock-Paper-Scissors-Lizzard-Spock), which, as I just learned, are simultaneous action selection games. While there are websites dedicated to playing specific games, such as webdiplomacy.net, we could not find a generic one that you can use if you, for example, invent your own variants of a game.
So I created one: At you-say-first.nomeata.de you can enter rooms and share the URL with your friends. On the one hand, you have a regular chat room there. But there is also the possibility to enter moves (whatever a move may be to you) and only when all players have done that and marked the move as final, it is shown to everyone. If you want to try it out: There is an integrated, not very fancy Rock-Paper-Scissors-playing bot. Just enter a room, join and say I want to play!
Note that this site can be used for more than just for games. Have you ever observed that persons would often want other to express their preference (e.g. where to dine) first to not reveal their own preference, so that they can (or pretend to) change their mind if they would contradict? In such situations simultaneous action selection can be a fairer method. A technical note: I created this web app using meteor (a JavaScript framework building on node.js and MongoDB that allows for reactive programming), and it is also hosted on meteor.com. I chose Meteor after someone mentioned Firebase to me, which looked very slick, but was not Free Software, so I looked for alternatives. I did not do any cross-browser-testing, and the UI design could be improved, so if you want to help out (or just complain), please use the GitHub code repository and issue tracker.

One of my recent innocent tweet about Gerrit vs Github triggered much more reponses and debate that I expected it to. I realize that it might be worth explaining a bit what I meant, in a text longer than 140 characters.

I'm having a hard time now contributing to projects not using Gerrit. Github isn't that good. Julien Danjou (@juldanjou) May 8, 2013

<script async="async" charset="utf-8" src="http://platform.twitter.com/widgets.js"></script> The problems with Github pull-requests I always looked at Github from a distant eye, mainly because I always disliked their pull-request handling, and saw no value in the social hype it brings. Why? One click away isn't one click effort The pull-request system looks like an incredible easy way to contribute to any project hosted on Github. You're a click away to send your contribution to any software. But the problem is that any worthy contribution isn't an effort of a single click. Doing any proper and useful contribution to a software is never done right the first time. There's a dance you will have to play. A slowly rhythmed back and forth between you and the software maintainer or team. You'll have to dance it until your contribution is correct and can be merged. But as a software maintainer, not everybody is going to follow you on this choregraphy, and you'll end up with pull-request you'll never get finished unless you wrap things up yourself. So the gain in pull-requests here, isn't really bigger than a good bug report in most cases. This is where the social argument of Github isn't anymore. As soon as you're talking about projects bigger than a color theme for your favorite text editor, this feature is overrated. Contribution rework If you're lucky enough, your contributor will play along and follow you on this pull-request review process. You'll make suggestions, he will listen and will modify his pull-request to follow your advice. At this point, there's two technics he can use to please you. Technic #1: the Topping Github's pull-requests invite you to send an entire branch, eclipsing the fact that it is composed of several commits. The problem is that a lot of one-click-away contributors do not masterize Git and/or do not make efforts to build a logical patchset, and nothing warns them that their branch history is wrong. So they tend to change stuff around, commit, make a mistake, commit, fix this mistake, commit, etc. This kind of branch is composed of the whole brain's construction process of your contributor, and is a real pain to review. To the point I quite often give up. <figure> <figcaption> A typical case: 3 commits to build a 4 lines long file. </figcaption> </figure> Without Github, the old method that all software used, and that many software still use (e.g. Linux), is to send a patch set over e-mail (or any other medium like Gerrit). This method has one positive effect, that it forces the contributor to acknowledge the list of commits he is going to publish. So, if the contributor he has fixup commits in his history, they are going to be seen as first class citizen. And nobody is going to want to see that, neither your contributor, nor the software maintainers. Therefore, such a system tend to push contributors to write atomic, logical and self-contained patchset that can be more easily reviewed. Technic #2: the History Rewriter This is actually the good way to build a working and logical patchset using Git. Rewriting history and amending problematic patches using the famous git rebase --interactive trick. The problem is that if your contributor does this and then repush the branch composing your pull-request to Github, you will both lose the previous review done, each time. There's no history on the different versions of the branch that has been pushed. In the old alternative system like e-mail, no information is lost when reworked patches are resent, obviously. This is far better because it eases the following of the iterative discussions that the patch triggered. Of course, it would be possible for Github to enhance this and fix it, but currently it doesn't handle this use case correctly.. <figure> <figcaption> Exercise for the doubtful readers: good luck finding all revisions of my patch in the pull-request #157 of Hy.</figcaption> </figure> A quick look at OpenStack workflow It's not a secret for anyone that I've been contributing to OpenStack as a daily routine for the last 18 months. The more I contribute, the more I like the contribution workflow and process. It's already well and longly described on the wiki, so I'll summarize here my view and what I like about it. Gerrit To send a contribution to any OpenStack project, you need to pass via Gerrit. This is way simpler than doing a pull-request on Github actually, all you have to do is do your commit(s), and type git review. That's it. Your patch will be pushed to Gerrit and available for review. Gerrit allows other developers to review your patch, add comments anywhere on it, and score your patch up or down. You can build any rule you want for the score needed for a patch to be merged; OpenStack requires one positive scoring from two core developers before the patch is merged. Until a patch is validated, it can be reworked and amended locally using Git, and then resent using git review again. That simple. The historic and the different version of the patches are available, with the whole comments. Gerrit doesn't lose any historic information on your workflow. Finally, you'll notice that this is actually the same kind of workflow projects use when they work by patch sent over e-mail. Gerrit just build a single place to regroup and keep track of patchsets, which is really handy. It's also much easier for people to actually send patch using a command line tool than their MUA or git send-email. Gate testing Testing is mandatory for any patch sent to OpenStack. Unit tests and functionnals test are run for each version of each patch of the patchset sent. And until your patch passes all tests, it will be impossible to merge it. Yes, this implies that all patches in a patchset must be working commits and can be merged on their own, without the entire patchset going in! With such a restricution, it's impossible to have "fixup commits" merged in your project and pollute the history and the testability of the project. Once your patch is validated by core developers, the system checks that there is not any merge conflicts. If there's not, tests are re-run, since the branch you are pushing to might have changed, and if everything's fine, the patch is merged. This is an uncredible force for the quality of the project. This implies that no broken patchset can ever sneak in, and that the project pass always all tests. Conclusion: accessibility vs code review In the end, I think that one of the key of any development process, which is code review, is not well covered by Github pull-request system. It is, along with history integrity, damaged by the goal of making contributions easier. Choosing between these features is probably a trade-off that each project should do carefully, considering what are its core goals and the quality of code it want to reach. I tend to find that OpenStack found one of the best trade-off available using Gerrit and plugging testing automation via Jenkins on it, and I would probably recommend it for any project taking seriously code reviews and testing.

Collabora recently had a problem with a project's ARM build farm. In a nice change of pace it was not that the kernel was crashing, nor indeed any of the software or hardware.
The ProblemInstead our problem was our build farm could best be described as "a pile of stuff" and we wanted to add more systems to it and have switched power control for automated testing.

Which is kinda where the Christopher Alexander quote comes into this. I suggested that I might be able to come up with a better, or at least cleaner, solution.
The IdeaPrevious experience had exposed me to the idea of using 19 inch subracks for mounting circuits inside submodules.

I originally envisaged the dev boards individually mounted inside these boxes. However preliminary investigation revealed that the enclosures were both expensive and used a lot of space which would greatly increase the rack space required to house these systems.

I decided to instead look at eurocard type subracks with carriers for the systems. Using my 3D printer I came up with a carrier design for the imx53 QSB and printed it. I used the basic eurocard size of 100mm x 160mm which would allow the cards to be used within a 3U subrack.

Once assembled it became apparent that each carrier would be able to share resources like power supply, ethernet port and serial console via USB just as the existing setup did and that these would need to be housed within the subrack.
The PrototypeThe carrier prototype was enough to get enough interest to allow me to move on to the next phase of the project. I purchased a Schroff 24563-194 subrack kit and three packs of guide rails from Farnell and assembled it.

Initially I had envisaged acquiring additional horizontal rails from Schroff which would enable constructing an area suitable for mounting the shared components behind the card area.

Unfortunately Schroff have no suitable horizontal profiles in their catalog and are another of those companies who seem to not want to actually sell products to end users but rather deal with wholesalers who do not have their entire product range!

Undaunted by this I created my own horizontal rail profile and 3D printed some lengths. The profile is designed to allow a 3mm thick rear cover sheet attached with M2.5 mounting bolts and fit rack sides in the same way the other profiles do.

At this point I should introduce some information on how these subracks are dimensioned. A standard 19 inch rack (as defined in IEC 60297) has a width of 17.75 inches(450.85mm) between the vertical posts. The height is measured in U (1.75 inches)

A subrack must obviously fit in the horizontal gap while providing as much internal space as possible. A subrack is generally either 3 or 6 U high. The width within a subrack is defined in units called HP (Horizontal Pitch) which are 0.2 inches(5.08 mm) and subracks like the Schroff generally list 84 usable HP.

However we must be careful (or actually just learn from me stuffing this up ;-) as the usable HP is not the same thing as the actual length of the horizontal rails! The enclosures actually leave and additional 0.1 inch at either end giving a total internal width of 85HP (17 inches, 431.8 mm) which leaves 0.75 inches for the subrack sides and some clearance.

The Schroff subrack allows eurocards to be slotted into rails where the card centre line is on HP boundaries, hence we describe the width of a card in the slot in terms of HP
I cannot manufacture aluminium extrusions (I know it is a personal failing) nor produce more than 100 mm long length of the plastic profile on my printer.

Even if full lengths are purchased from a commercial service (120 euros for a pair including tax and shipping) the plastic does not have sufficient mechanical strength.

The solution I came up with was somewhat innovative, as an alternative a M5 bolt into a thread in the aluminium extrusion I used a 444mm long length of 4mm threaded rod with nuts at either end. This arrangement puts the extrusion under compression and gives it a great deal of additional mechanical strength as the steel threaded rod is very strong.

Additionally to avoid having to print enough extrusion for the entire length I used some 6mm aluminium tube as a spacer between 6HP(30.48mm) wide sections of the printed extrusion.

It was intended to use a standard modular PC power supply which is 150mm wide which is pretty close to 30HP (6 inches) so it was decided to have a 6HP section of rail at that point to allow a rear mounting plate for the PSU to be attached.

This gives 6HP of profile, 21HP(106.68mm) of tube spacer, 6HP of profile, 46HP(233.68 mm) of tube spacer and a final 6HP profile summing to our total of 85HP. Of course this would be unnecessary if a full continuous 85HP rail had been purchased, but 6 of 6 HP long profile is only 51 euro a saving of 70 euro.

To provide a flat area on which to mount the power switching, Ethernet switch and USB hubs I ordered a 170 x 431 mm sheet of 3mm thick aluminium from inspiredsteel who, while being an ebay company, were fast, cheap and the cutting was accurate.

Do be sure to mention you would prefer it if any error made the sheet smaller rather than larger or it might not fit, for me though they were accurate to the tenth of a mm! If you would prefer the rear section of the rack to be enclosed when you are finished, buy a second sheet for the top. For my prototype I only purchased a 170 x 280mm sheet as I was unsure if I wanted a surface under the PSU (you do, buy the longer sheet)

Mounting the PSU was a simple case of constructing a 3 mm thick plate with the correct cutouts and mounting holes for an ATX supply. Although the images show the PSU mounted on the left hand side of the rack this was later reversed to improve cable management.

The subrack needed to provide Ethernet switch ports to all the systems. A TP-Link TL-SF1016DS 16-Port 10/100Mbps Switch was acquired and the switch board removed from its enclosure. The switch selected has an easily removed board and is powered by a single 3.3V input which is readily available from the ATX PSU.

Attention now returned to the eurocard carriers for the systems, the boards to be housed were iMX53 QSB and iMX6 SABRE Lite and a Raspberry Pi control system to act as USB serial console etc.

The carriers for both main boards needed to be 8HP wide, comprised of:

• Combined USB and Ethernet Jack on both boards was 30 mm tall
• PCB width of 2mm
• underside components of 4mm
• clearance between boards of 2mm

A wiring loom was constructed for each board giving them a connector tail long enough to allow them to be removed. This was the wrong approach! if you implement this design (or when I do it again) the connector tails on the wiring loom should present all the connections to the rear at the same depth as the Ethernet connection.

The rack cables themselves should be long enough to allow the slides to be removed but importantly it is not desirable to have the trailing cable on the cards. I guess the original eurocard designers figured this out as they designed the cards around the standard fixed DIN connectors at the back of the card slots.

We will now briefly examine a misjudgement that caused the initially deployed solution to be reimplemented. As the design was going to use USB serial converters to access the serial console a USB connected relay board was selected to switch the power to each slot. I had previously used serial controlled relay boards with a USB serial convertor however these were no longer available.

All the available USB relay boards were HID controlled, this did not initially seem to be an issue and Linux software was written to provide a reasonable interface. However it soon became apparent that the firmware on the purchased board was very buggy and crashed the host computer's USB stack multiple times.

Deployed solutionOnce it became apparent that the USB controlled power board was not viable a new design was conceived. As the Ethernet switch had ports available Ethernet controlled relay boards were acquired.

It did prove necessary to design and print some PCB support posts with M3 nut traps to allow the relay boards to be easily mounted using double sided adhesive pads.

By stacking the relay boards face to face and the Ethernet switch on top separated using nylon spacers it was possible to reduce the cable clutter and provide adequate cable routing space.

A busbar for Ground (black) and unswitched 12V (yellow) was constructed from two lengths of 5A chock block.

An issue with power supply stability was noted so a load resistor was added to the 12V supply and an adhesive thermal pad used to attach it to the aluminium base plate.

It was most fortunate that the ethernet switch mounting holes lined up very well with the relay board mounting holes allowing for a neat stack.

This second edition is the one currently in use, it has proved reliable in operation and has been successfully updated with additional carriers.

The outstanding issues are mainly centered around the Raspberry Pi control board:

• Needs its carrier fitting. It is currently just stuck to the subrack end plate.
• Needs its Ethernet cable replacing. The existing one has developed a fault post installation.
• Needs the USB hub supply separating from the device cable. The current arrangement lets the hub power the Pi which means you cannot power cycle it.
• Connect its switched supply separately to the USB hub/devices.

Shopping listThe final bill of materials (excluding labour and workshop costs) which might be useful to anyone hoping to build their own version.

Prices are in GBP currency converted where appropriate and include tax at 20% and delivery to Cambridge UK and were correct as of April 2013.

The purchasing was not optimised and for example around 20GBP could be saved just by ordering all the shapeways parts in one order.

Base subrack
Item	Supplier	Quantity	Line Price
Schroff 24563-194 subrack kit	Farnell	1	41.28
Schroff 24560-351 guide rails	Farnell	3	13.65
Schroff rack rear horizontal rail	Shapeways	2	100.00
1000mm length of 4mm threaded rod	B and Q	1	1.48
170mm x 431mm x 3mm Aluminium sheet	inspired steel	2	40.00
PSU mounting plate	Shapeways	1	35.42
PCB standoff	Shapeways	4	22.30
160mm Deep Modular PC supply	CCL	1	55.76
TP-Link TL-SF1016DS 16-Port 10/100Mbps-Switch	CCL	1	23.77
8 Channel 16A Relay Board Controlled Via Ethernet	Rapid	2	126.00
Raspberry Pi	Farnell	1	26.48
USB Serial converters	CCL	10	37.40
10 port strip style USB HUB	Ebay	1	7.00
Parts for custom Ethernet cables	RS	13	26.00
Parts for custom molex power cables (salvaged from scrap ATX PSU)	Workshop	11	11.00
33R 10W wirewound resistor for dummy load	RS	1	1.26
24pin ATX female connector pre-wired	Maplin	1	2.99
Akasa double sided thermal pad	Maplin	1	5.00
Small cable tie bases	Maplin	1	6.49
Miscellaneous cable, connectors, nylon standoffs, solder, heatshrink, zip ties, nuts, washers etc.	Workshop	1	20.00
Total for subrack			603.28

The carriers are similarly not optimally priced as over five GBP each can be saved by combining shipping on orders alone. Also the SSD drive selection was made some time ago and a newer model may be more suitable.

i.MX53 QSB carrier
Item	Supplier	Quantity	Line Price
i.MX53 QSB	Farnell	1	105.52
Intel 320 SSD 80G	CCL	1	111.83
Carrier board	Shapeways	1	30.00
combined sata data and power (15 to 20cm version)	EBay	1	5.00
Low profile right angle 5.5mm x 2.1mm barrel jack	EBay	1	0.25
Parts for 9pin serial cable extension	RS	1	5.00
Miscellaneous solder, heatshrink, nylon nuts, bolts and washers	Workshop	1	5.00
Total for carrier			262.60

i.MX6 SABRE Lite carrier
Item	Supplier	Quantity	Line Price
i.MX6 SABRE Lite	Farnell	1	128.06
Intel 320 SSD 80G	CCL	1	111.83
Carrier board	Shapeways	1	35.00
combined sata data and power (15 to 20cm version)	EBay	1	5.00
Low profile right angle 5.5mm x 2.1mm barrel jack	EBay	1	0.25
Parts for 9pin serial cable modification	RS	1	2.00
Miscellaneous solder, heatshrink, nylon nuts, bolts and washers	Workshop	1	5.00
Total for carrier			287.14

ConclusionThe solution works and in a 3U high 355mm deep subrack ten ARM development boards can be racked complete with local ethernet switching, power control and serial consoles.

The solution is neat and provides flexibility, density and reproducibility the "pile of stuff" solution failed to do.

For current prototype with nine filled slots the total cost was around 3000GBP or around 330GBP per slot which indicates a 100GBP per slot overhead over the "pile of stuff" solution. These figures omit the costs of the engineer and workshop time, which are estimated at an additional 1500GBP. Therefore a completed rack, fully filled with i.MX6 carriers costs around 5000GBP

Density could be increased if boards with lower height requirements were used however above twelve units there issues with Ethernet switch, power switch and USB port availability become a factor. For Example the 16 port Ethernet switch requires a port for uplink, one for each relay board and one for the console server which leaves only 12 ports for systems.

Addressing the outstanding issues would result in a much more user friendly solution. As the existing unit is in full time use and downtime is not easily scheduled for all ten systems, the issues are not likely to be fixed on the prototype and would have to be solved on a new build.

The solution is probably not suitable for turning into a product but that was not really the original aim. A commercial ARM blade server using this format would almost certainly use standard DIN connectors and a custom PCB design rather than adapting existing boards.

The first Qt 5 packages have been accepted in Debian experimental.

What's there

• qtbase-opensource-src: lib[concurrent core dbus gui network opengl printsupport sql test widgets xml], examples, development packages and debug symbols.
• qttools-opensource-src: lib[qtlucene designer help], qdbus, development headers and debugging symbols.
• qtjsbackend-opensource-src: libqt5v8-5
• qtxmlpatterns-opensource-src
• qtchooser, which allows to select between Qt4 or Qt5 at build time.

What's not there