Category Archives: Technology

Emacs #2: Introducing org-mode

In my first post in my series on Emacs, I described returning to Emacs after over a decade of vim, and org-mode being the reason why.

I really am astounded at the usefulness, and simplicity, of org-mode. It is really a killer app.

So what exactly is org-mode?

I wrote yesterday:

It’s an information organization platform. Its website says “Your life in plain text: Org mode is for keeping notes, maintaining TODO lists, planning projects, and authoring documents with a fast and effective plain-text system.”

That’s true, but doesn’t quite capture it. org-mode is a toolkit for you to organize things. It has reasonable out-of-the-box defaults, but it’s designed throughout for you to customize.

To highlight a few things:

  • Maintaining TODO lists: items can be scattered across org-mode files, contain attachments, have tags, deadlines, schedules. There is a convenient “agenda” view to show you what needs to be done. Items can repeat.
  • Authoring documents: org-mode has special features for generating HTML, LaTeX, slides (with LaTeX beamer), and all sorts of other formats. It also supports direct evaluation of code in-buffer and literate programming in virtually any Emacs-supported language. If you want to bend your mind on this stuff, read this article on literate devops. The entire Worg website
    is made with org-mode.
  • Keeping notes: yep, it can do that too. With full-text search, cross-referencing by file (as a wiki), by UUID, and even into other systems (into mu4e by Message-ID, into ERC logs, etc, etc.)

Getting started

I highly recommend watching Carsten Dominik’s excellent Google Talk on org-mode. It is an excellent introduction.

org-mode is included with Emacs, but you’ll often want a more recent version. Debian users can apt-get install org-mode, or it comes with the Emacs packaging system; M-x package-install RET org-mode RET may do it for you.

Now, you’ll probably want to start with the org-mode compact guide’s introduction section, noting in particular to set the keybindings mentioned in the activation section.

A good tutorial…

I’ve linked to a number of excellent tutorials and introductory items; this post is not going to serve as a tutorial. There are two good videos linked at the end of this post, in particular.

Some of my configuration

I’ll document some of my configuration here, and go into a bit of what it does. This isn’t necessarily because you’ll want to copy all of this verbatim — but just to give you a bit of an idea of some of what can be configured, an idea of what to look up in the manual, and maybe a reference for “now how do I do that?”

First, I set up Emacs to work in UTF-8 by default.

(prefer-coding-system 'utf-8)
(set-language-environment "UTF-8")

org-mode can follow URLs. By default, it opens in Firefox, but I use Chromium.

(setq browse-url-browser-function 'browse-url-chromium)

I set the basic key bindings as documented in the Guide, plus configure the M-RET behavior.

(global-set-key "\C-cl" 'org-store-link)
(global-set-key "\C-ca" 'org-agenda)
(global-set-key "\C-cc" 'org-capture)
(global-set-key "\C-cb" 'org-iswitchb)

(setq org-M-RET-may-split-line nil)

Configuration: Capturing

I can press C-c c from anywhere in Emacs. It will capture something for me, and include a link back to whatever I was working on.

You can define capture templates to set how this will work. I am going to keep two journal files for general notes about meetings, phone calls, etc. One for personal, one for work items. If I press C-c c j, then it will capture a personal item. The %a in all of these includes the link to where I was (or a link I had stored with C-c l).

(setq org-default-notes-file "~/org/tasks.org")
(setq org-capture-templates
      '(
        ("t" "Todo" entry (file+headline "inbox.org" "Tasks")
         "* TODO %?\n  %i\n  %u\n  %a")
        ("n" "Note/Data" entry (file+headline "inbox.org" "Notes/Data")
         "* %?   \n  %i\n  %u\n  %a")
        ("j" "Journal" entry (file+datetree "~/org/journal.org")
         "* %?\nEntered on %U\n %i\n %a")
        ("J" "Work-Journal" entry (file+datetree "~/org/wjournal.org")
         "* %?\nEntered on %U\n %i\n %a")
        ))
(setq org-irc-link-to-logs t)

I like to link by UUIDs, which lets me move things between files without breaking locations. This helps generate UUIDs when I ask Org to store a link target for future insertion.


(require 'org-id)
(setq org-id-link-to-org-use-id 'create-if-interactive)

Configuration: agenda views

I like my week to start on a Sunday, and for org to note the time when I mark something as done.


(setq org-log-done 'time)
(setq org-agenda-start-on-weekday 0)

Configuration: files and refiling

Here I tell it what files to use in the agenda, and to add a few more to the plain text search. I like to keep a general inbox (from which I can move, or “refile”, content), and then separate tasks, journal, and knowledge base for personal and work items.

  (setq org-agenda-files (list "~/org/inbox.org"
                               "~/org/email.org"
                               "~/org/tasks.org"
                               "~/org/wtasks.org"
                               "~/org/journal.org"
                               "~/org/wjournal.org"
                               "~/org/kb.org"
                               "~/org/wkb.org"
  ))
  (setq org-agenda-text-search-extra-files
        (list "~/org/someday.org"
              "~/org/config.org"
  ))

  (setq org-refile-targets '((nil :maxlevel . 2)
                             (org-agenda-files :maxlevel . 2)
                             ("~/org/someday.org" :maxlevel . 2)
                             ("~/org/templates.org" :maxlevel . 2)
                             )
        )
(setq org-outline-path-complete-in-steps nil)         ; Refile in a single go
(setq org-refile-use-outline-path 'file)

Configuration: Appearance

I like a pretty screen. After you’ve gotten used to org a bit, you might try this.

(require 'org-bullets)
(add-hook 'org-mode-hook
          (lambda ()
            (org-bullets-mode t)))
(setq org-ellipsis "⤵")

Coming up next…

This hopefully showed a few things that org-mode can do. Coming up next, I’ll cover how to customize TODO keywords and tags, archiving old tasks, forwarding emails to org-mode, and using git to synchronize between machines.

You can also see a list of all articles in this series.

Resources to accompany this article

Emacs #1: Ditching a bunch of stuff and moving to Emacs and org-mode

I’ll admit it. After over a decade of vim, I’m hooked on Emacs.

I’ve long had this frustration over how to organize things. I’ve followed approaches like GTD and ZTD, but things like email or large files are really hard to organize.

I had been using Asana for tasks, Evernote for notes, Thunderbird for email, a combination of ikiwiki and some other items for a personal knowledge base, and various files in an archive directory on my PC. When my new job added Slack to the mix, that was finally the last straw.

A lot of todo-management tools integrate with email — poorly. When you want to do something like “remind me to reply to this in a week”, a lot of times that’s impossible because the tool doesn’t store the email in a fashion you can easily reply to. And that problem is even worse with Slack.

It was right around then that I stumbled onto Carsten Dominik’s Google Talk on org-mode. Carsten was the author of org-mode, and although the talk is 10 years old, it is still highly relevant.

I’d stumbled across org-mode before, but each time I didn’t really dig in because I had the reaction of “an outliner? But I need a todo list.” Turns out I was missing out. org-mode is all that.

Just what IS Emacs? And org-mode?

Emacs grew up as a text editor. It still is, and that heritage is definitely present throughout. But to say Emacs is an editor would be rather unfair.

Emacs is something more like a platform or a toolkit. Not only do you have source code to it, but the very configuration is a program, and there are hooks all over the place. It’s as if it was super easy to write a Firefox plugin. A couple lines, and boom, behavior changed.

org-mode is very similar. Yes, it’s an outliner, but that’s not really what it is. It’s an information organization platform. Its website says “Your life in plain text: Org mode is for keeping notes, maintaining TODO lists, planning projects, and authoring documents with a fast and effective plain-text system.”

Capturing

If you’ve ever read productivity guides based on GTD, one of the things they stress is effortless capture of items. The idea is that when something pops into your head, get it down into a trusted system quickly so you can get on with what you were doing. org-mode has a capture system for just this. I can press C-c c from anywhere in Emacs, and up pops a spot to type my note. But, critically, automatically embedded in that note is a link back to what I was doing when I pressed C-c c. If I was editing a file, it’ll have a link back to that file and the line I was on. If I was viewing an email, it’ll link back to that email (by Message-Id, no less, so it finds it in any folder). Same for participating in a chat, or even viewing another org-mode entry.

So I can make a note that will remind me in a week to reply to a certain email, and when I click the link in that note, it’ll bring up the email in my mail reader — even if I subsequently archived it out of my inbox.

YES, this is what I was looking for!

The tool suite

Once you’re using org-mode, pretty soon you want to integrate everything with it. There are browser plugins for capturing things from the web. Multiple Emacs mail or news readers integrate with it. ERC (IRC client) does as well. So I found myself switching from Thunderbird and mairix+mutt (for the mail archives) to mu4e, and from xchat+slack to ERC.

And wouldn’t you know it, I liked each of those Emacs-based tools better than the standalone they replaced.

A small side tidbit: I’m using OfflineIMAP again! I even used it with GNUS way back when.

One Emacs process to rule them

I used to use Emacs extensively, way back. Back then, Emacs was a “large” program. (Now my battery status applet literally uses more RAM than Emacs). There was this problem of startup time back then, so there was a way to connect to a running Emacs process.

I like to spawn programs with Mod-p (an xmonad shortcut to a dzen menubar, but Alt-F2 in more traditional DEs would do the trick). It’s convenient to not run several emacsen with this setup, so you don’t run into issues with trying to capture to a file that’s open in another one. The solution is very simple: I created a script, named it em, and put it on my path. All it does is this:


#!/bin/bash
exec emacsclient -c -a "" "$@"

It creates a new emacs process if one doesn’t already exist; otherwise, it uses what you’ve got. A bonus here: parameters such as -nw work just fine, so it really acts just as if you’d typed emacs at the shell prompt. It’s a suitable setting for EDITOR.

Up next…

I’ll be talking about my use of, and showing off configurations for:

  • org-mode, including syncing between computers, capturing, agenda and todos, files, linking, keywords and tags, various exporting (slideshows), etc.
  • mu4e for email, including multiple accounts, bbdb integration
  • ERC for IRC and IM

You can also see a list of all articles in this series.

How are you handling building local Debian/Ubuntu packages?

I’m in the middle of some conversations about Debian/Ubuntu repositories, and I’m curious how others are handling this.

How are people maintaining repos for an organization? Are you integrating them with a git/CI (github/gitlab, jenkins/travis, etc) workflow? How do packages propagate into repos? How do you separate prod from testing? Is anyone running buildd locally, or integrating with more common CI tools?

I’m also interested in how people handle local modifications of packages — anything from newer versions of C libraries to newer interpreters. Do you just use the regular Debian toolchain, packaging them up for (potentially) the multiple distros/versions that you have in production? Pin them in apt?

Just curious what’s out there.

Some Googling has so far turned up just one relevant hit: Michael Prokop’s DebConf15 slides, “Continuous Delivery of Debian packages”. Looks very interesting, and discusses jenkins-debian-glue.

Some tangentially-related but interesting items:

Edit 2018-02-02: I should have also mentioned BuildStream

An old DOS BBS in a Docker container

Awhile back, I wrote about my Debian Docker base images. I decided to extend this concept a bit further: to running DOS applications in Docker.

But first, a screenshot:

It turns out this is possible, but difficult. I went through all three major DOS emulators available (dosbox, qemu, and dosemu). I got them all running inside the Docker container, but had a number of, er, fun issues to resolve.

The general thing one has to do here is present a fake modem to the DOS environment. This needs to be exposed outside the container as a TCP port. That much is possible in various ways — I wound up using tcpser. dosbox had a TCP modem interface, but it turned out to be too buggy for this purpose.

The challenge comes in where you want to be able to accept more than one incoming telnet (or TCP) connection at a time. DOS was not a multitasking operating system, so there were any number of hackish solutions back then. One might have had multiple physical computers, one for each incoming phone line. Or they might have run multiple pseudo-DOS instances under a multitasking layer like DESQview, OS/2, or even Windows 3.1.

(Side note: I just learned of DESQview/X, which integrated DESQview with X11R5 and replaced the Windows 3 drivers to allow running Windows as an X application).

For various reasons, I didn’t want to try running one of those systems inside Docker. That left me with emulating the original multiple physical node setup. In theory, pretty easy — spin up a bunch of DOS boxes, each using at most 1MB of emulated RAM, and go to town. But here came the challenge.

In a multiple-physical-node setup, you need some sort of file sharing, because your nodes have to access the shared message and file store. There were a myriad of clunky ways to do this in the old DOS days – Netware, LAN manager, even some PC NFS clients. I didn’t have access to Netware. I tried the Microsoft LM client in DOS, talking to a Samba server running inside the Docker container. This I got working, but the LM client used so much RAM that, even with various high memory tricks, BBS software wasn’t going to run. I couldn’t just mount an underlying filesystem in multiple dosbox instances either, because dosbox did caching that wasn’t going to be compatible.

This is why I wound up using dosemu. Besides being a more complete emulator than dosbox, it had a way of sharing the host’s filesystems that was going to work.

So, all of this wound up with this: jgoerzen/docker-bbs-renegade.

I also prepared building blocks for others that want to do something similar: docker-dos-bbs and the lower-level docker-dosemu.

As a side bonus, I also attempted running this under Joyent’s Triton (SmartOS, Solaris-based). I was pleasantly impressed that I got it all almost working there. So yes, a Renegade DOS BBS running under a Linux-based DOS emulator in a container on a Solaris machine.

The Yellow House Phone Company (Featuring Asterisk and an 11-year-old)

“Well Jacob, do you think we should set up our own pretend phone company in the house?”

“We can DO THAT?”

“Yes!”

“Then… yes. Yes! YES YES YESYESYESYES YES! Let’s do it, dad!”

Not long ago, my parents had dug up the old phone I used back in the day. We still have a landline, and Jacob was having fun discovering how an analog phone works. I told him about the special number he could call to get the time and temperature read out to him. He discovered what happens if you call your own number and hang up. He figured out how to play “Mary Had a Little Lamb” using touchtone keys (after a slightly concerned lecture from me setting out some rules to make sure his “musical dialing” wouldn’t result in any, well, dialing.)

He was hooked. So I thought that taking it to the next level would be a good thing for a rainy day. I have run Asterisk before, though I had unfortunately gotten rid of most of my equipment some time back. But I found a great deal on a Cisco 186 ATA (Analog Telephone Adapter). It has two FXS lines (FXS ports simulate the phone company, and provide dialtone and ring voltage to a connected phone), and of course hooks up to the LAN.

We plugged that in, and Jacob was amazed to see its web interface come up. I had to figure out how to configure it (unfortunately, it uses SCCP rather than SIP, and figuring out Asterisk’s chan_skinny took some doing, but we got there.)

I set up voicemail. He loved it. He promptly figured out how to record his own greetings. We set up a second phone on the other line, so he could call between them. The cordless phones in our house support SIP, so I configured one of them as a third line. He spent a long time leaving himself messages.

IMG_3465

Pretty soon we both started having ideas. I set up extension 777, where he could call for the time. Then he wanted a way to get the weather forecast. Well, weather-util generates a text-based report. With it, a little sed and grep tweaking, the espeak TTS engine, and a little help from sox, I had a shell script worked up that would read back a forecast whenever he called a certain extension. He was super excited! “That’s great, dad! Can it also read weather alerts too?” Sure! weather-util has a nice option just for that. Both boys cackled as the system tried to read out the NWS header (their timestamps like 201711031258 started with “two hundred one billion…”)

Then I found an online source for streaming NOAA Weather Radio feeds – Jacob enjoys listening to weather radio – and I set up another extension he could call to listen to that. More delight!

But it really took off when I asked him, “Would you like to record your own menu?” “You mean those things where it says press 1 or 2 for this or that?” “Yes.” “WE CAN DO THAT?” “Oh yes!” “YES, LET’S DO IT RIGHT NOW!”

So he recorded a menu, then came and hovered by me while I hacked up extensions.conf, then eagerly went back to the phone to try it. Oh the excitement of hearing hisown voice, and finding that it worked! Pretty soon he was designing sub-menus (“OK Dad, so we’ll set it up so people can press 2 for the weather, and then choose if they want weather radio or the weather report. I’m recording that now. Got it?”)

He has informed me that next Saturday we will build an intercom system “like we have at school.” I’m going to have to have some ideas on how to tie Squeezebox in with Asterisk to make that happen, I think. Maybe this will do.

Switching to xmonad + Gnome – and ditching a Mac

I have been using XFCE with xmonad for years now. I’m not sure exactly how many, but at least 6 years, if not closer to 10. Today I threw in the towel and switched to Gnome.

More recently, at a new job, I was given a Macbook Pro. I wasn’t entirely sure what to think of this, but I thought I’d give it a try. I found MacOS to be extremely frustrating and confining. It had no real support for a tiling window manager, and although projects like amethyst tried to approximate what xmonad can do on Linux, they were just too limited by the platform and were clunky. Moreover, the entire UI was surprisingly sluggish; maybe that was an induced effect from animations, but I don’t think that explains it. A Debisn stretch install, even on inferior hardware, was snappy in a way that MacOS never was. So I have requested to swap for a laptop that will run Debian. The strange use of Command instead of Control for things, combined with the overall lack of configurability of keybindings, meant that I was going to always be fighting muscle memory moving from one platform to another. Not only that, but being back in the world of a Free Software OS means a lot.

Now then, back to xmonad and XFCE situation. XFCE once worked very well with xmonad. Over the years, this got more challenging. Around the jessie (XFCE 4.10) time, I had to be very careful about when I would let it save my session, because it would easily break. With stretch, I had to write custom scripts because the panel wouldn’t show up properly, and even some application icons would be invisible, if things were started in a certain order. This took much trial and error and was still cumbersome.

Gnome 3, with its tightly-coupled Gnome Shell, has never been compatible with other window managers — at least not directly. A person could have always used MATE with xmonad — but a lot of people that run XFCE tend to have some Gnome 3 apps (for instance, evince) anyhow. Cinnamon also wouldn’t work with xmonad, because it is simply another tightly-coupled shell instead of Gnome Shell. And then today I discovered gnome-flashback. gnome-flashback is a Gnome 3 environment that uses the traditional X approach with a separate window manager (metacity of yore by default). Sweet.

It turns out that Debian’s xmonad has built-in support for it. If you know the secret: apt-get install gnome-session-flashback (OK, it’s not so secret; it’s even in xmonad’s README.Debian these days) Install that, plus gnome and gdm3 and things are nice. Configure xmonad with GNOME support and poof – goodness right out of the box, selectable from the gdm sessions list.

I still have some gripes about Gnome’s configurability (or lack thereof). But I’ve got to say: This environment is the first one I’ve ever used that got external display switching very nearly right without any configuration, and I include MacOS in that. Plug in an external display, and poof – it’s configured and set up. You can hit a toggle key (Windows+P by default) to change the configurations, or use the Display section in gnome-control-center. Unplug it, and it instantly reconfigures itself to put everything back on the laptop screen. Yessss! I used to have scripts to do this in the wheezy/jessie days. XFCE in stretch had numerous annoying failures in this area which rendered the internal display completely dark until the next reboot – very frustrating. With Gnome, it just works. And, even if you have “suspend on lid closed” turned on, if the system is powered up and hooked up to an external display, it will keep running even if the lid is closed, figuring you must be using it on the external screen. Another thing the Mac wouldn’t do well.

All in all, some pretty good stuff here. I continue to be impressed by stretch. It is darn impressive to put this OS on generic hardware and have it outshine the closed-ecosystem Mac!

The Joy of Exploring: Old Phone Systems, Pizza, and Discovery

This story involves boys pretending to be pizza deliverymen using a working automated Strowger telephone exchange demonstrator on display in a museum, which is very old and is, to my knowledge, the only such working exhibit in the world. (Yes, I have video.) But first, a thought on exploration.

There are those that would say that there is nothing left to explore anymore – that the whole earth is mapped, photographed by satellites, and, well, known.

I prefer to look at it a different way: the earth is full of places that billions of people will never see, and probably don’t even know about. Those places may be quiet country creeks, peaceful neighborhoods one block away from major tourist attractions, an MTA museum in Brooklyn, a state park in Arkansas, or a beautiful church in Germany.

Martha is not yet two months old, and last week she and I spent a surprisingly long amount of time just gazing at tree branches — she was mesmerized, and why not, because to her, everything is new.

As I was exploring in Portland two weeks ago, I happened to pick up a nearly-forgotten book by a nearly-forgotten person, Beryl Markham, a woman who was a pilot in Africa about 80 years ago. The passage that I happened to randomly flip to in the bookstore, which really grabbed my attention, was this:

The available aviation maps of Africa in use at that time all bore the cartographer’s scale mark, ‘1/2,000,000’ — one over two million. An inch on the map was about thitry-two miles in the air, as compared to the flying maps of Europe on which one inch represented no more than four air miles.

Moreover, it seemed that the printers of the African maps had a slightly malicious habit of including, in large letters, the names of towns, junctions, and villages which, while most of them did exist in fact, as a group of thatched huts may exist or a water hold, they were usually so inconsequential as completely to escape discovery from the cockpit.

Beyond this, it was even more disconcerting to examine your charts before a proposed flight only to find that in many cases the bulk of the terrain over which you had to fly was bluntly marked: ‘UNSURVEYED’.

It was as if the mapmakers had said, “We are aware that between this spot and that one, there are several hundred thousands of acres, but until you make a forced landing there, we won’t know whether it is mud, desert, or jungle — and the chances are we won’t know then!”

— Beryl Markham, West With the Night

My aviation maps today have no such markings. The continent is covered with radio beacons, the world with GPS, the maps with precise elevations of the ground and everything from skyscrapers to antenna towers.

And yet, despite all we know, the world is still a breathtaking adventure.

Yesterday, the boys and I were going to fly to Abilene, KS, to see a museum (Seelye Mansion). Circumstances were such that we neither flew, nor saw that museum. But we still went to Abilene, and wound up at the Museum of Independent Telephony, a wondrous place for anyone interested in the history of technology. As it is one of those off-the-beaten-path sorts of places, the boys got 2.5 hours to use the hands-on exhibits of real old phones, switchboards, and also the schoolhouse out back. They decided — why not? — to use this historic equipment to pretend to order pizzas.

Jacob and Oliver proceeded to invent all sorts of things to use the phones for: ordering pizza, calling the cops to chase the pizza delivery guys, etc. They were so interested that by 2PM we still hadn’t had lunch and they claimed “we’re not hungry” despite the fact that we were going to get pizza for lunch. And I certainly enjoyed the exhibits on the evolution of telephones, switching (from manual plugboards to automated switchboards), and such.

This place was known – it even has a website, I had been there before, and in fact so had the boys (my parents took them there a couple of years ago). But yesterday, we discovered the Strowger switch had been repaired since the last visit, and that it, in fact, is great for conversations about pizza.

Whether it’s seeing an eclipse, discovering a fascination with tree branches, or historic telephones, a spirit of curiosity and exploration lets a person find fun adventures almost anywhere.

Fixing the Problems with Docker Images

I recently wrote about the challenges in securing Docker container contents, and in particular with keeping up-to-date with security patches from all over the Internet.

Today I want to fix that.

Besides security, there is a second problem: the common way of running things in Docker pretends to provide a traditional POSIX API and environment, but really doesn’t. This is a big deal.

Before diving into that, I want to explain something: I have often heard it said the Docker provides single-process containers. This is unambiguously false in almost every case. Any time you have a shell script inside Docker that calls cp or even ls, you are running a second process. Web servers from Apache to whatever else use processes or threads of various types to service multiple connections at once. Many Docker containers are single-application, but a process is a core part of the POSIX API, and very little software would work if it was limited to a single process. So this is my little plea for more precise language. OK, soapbox mode off.

Now then, in a traditional Linux environment, besides your application, there are other key components of the system. These are usually missing in Docker containers.

So today, I will fix this also.

In my docker-debian-base images, I have prepared a system that still has only 11MB RAM overhead, makes minimal changes on top of Debian, and yet provides a very complete environment and API. Here’s what you get:

  • A real init system, capable of running standard startup scripts without modification, and solving the nasty Docker zombie reaping problem.
  • Working syslog, which can either export all logs to Docker’s logging infrastructure, or keep them within the container, depending on your preferences.
  • Working real schedulers (cron, anacron, and at), plus at least the standard logrotate utility to help prevent log files inside the container from becoming huge.

The above goes into my “minimal” image. Additional images add layers on top of it, and here are some of the features they add:

  • A real SMTP agent (exim4-daemon-light) so that cron and friends can actually send you mail
  • SSH client and server (optionally exposed to the Internet)
  • Automatic security patching via unattended-upgrades and needsrestart

All of the above, including the optional features, has an 11MB overhead on start. Not bad for so much, right?

From here, you can layer on top all your usual Dockery things. You can still run one application per container. But you can now make sure your disk doesn’t fill up from logs, run your database vacuuming commands at will, have your blog download its RSS feeds every few minutes, etc — all from within the container, as it should be. Furthermore, you don’t have to reinvent the wheel, because Debian already ships with things to take care of a lot of this out of the box — and now those tools will just work.

There is some popular work done in this area already by phusion’s baseimage-docker. However, I made my own for these reasons:

  • I wanted something based on Debian rather than Ubuntu
  • By using sysvinit rather than runit, the OS default init scripts can be used unmodified, reducing the administrative burden on container builders
  • Phusion’s system is, for some reason, not auto-built on the Docker hub. Mine is, so it will be automatically revised whenever the underlying Debian system, or the Github repository, is.

Finally a word on the choice to use sysvinit. It would have been simpler to use systemd here, since it is the default in Debian these days. Unfortunately, systemd requires you to poke some holes in the Docker security model, as well as mount a cgroups filesystem from the host. I didn’t consider this acceptable, and sysvinit ran without these workarounds, so I went with it.

With all this, Docker becomes a viable replacement for KVM for various services on my internal networks. I’ll be writing about that later.

Silent Data Corruption Is Real

Here’s something you never want to see:

ZFS has detected a checksum error:

   eid: 138
 class: checksum
  host: alexandria
  time: 2017-01-29 18:08:10-0600
 vtype: disk

This means there was a data error on the drive. But it’s worse than a typical data error — this is an error that was not detected by the hardware. Unlike most filesystems, ZFS and btrfs write a checksum with every block of data (both data and metadata) written to the drive, and the checksum is verified at read time. Most filesystems don’t do this, because theoretically the hardware should detect all errors. But in practice, it doesn’t always, which can lead to silent data corruption. That’s why I use ZFS wherever I possibly can.

As I looked into this issue, I saw that ZFS repaired about 400KB of data. I thought, “well, that was unlucky” and just ignored it.

Then a week later, it happened again. Pretty soon, I noticed it happened every Sunday, and always to the same drive in my pool. It so happens that the highest I/O load on the machine happens on Sundays, because I have a cron job that runs zpool scrub on Sundays. This operation forces ZFS to read and verify the checksums on every block of data on the drive, and is a nice way to guard against unreadable sectors in rarely-used data.

I finally swapped out the drive, but to my frustration, the new drive now exhibited the same issue. The SATA protocol does include a CRC32 checksum, so it seemed (to me, at least) that the problem was unlikely to be a cable or chassis issue. I suspected motherboard.

It so happened I had a 9211-8i SAS card. I had purchased it off eBay awhile back when I built the server, but could never get it to see the drives. I wound up not filling it up with as many drives as planned, so the on-board SATA did the trick. Until now.

As I poked at the 9211-8i, noticing that even its configuration utility didn’t see any devices, I finally started wondering if the SAS/SATA breakout cables were a problem. And sure enough – I realized I had a “reverse” cable and needed a “forward” one. $14 later, I had the correct cable and things are working properly now.

One other note: RAM errors can sometimes cause issues like this, but this system uses ECC DRAM and the errors would be unlikely to always manifest themselves on a particular drive.

So over the course of this, had I not been using ZFS, I would have had several megabytes of reads with undetected errors. Thanks to using ZFS, I know my data integrity is still good.

Two Boys, An Airplane, Plus Hundreds of Old Computers

“Was there anything you didn’t like about our trip?”

Jacob’s answer: “That we had to leave so soon!”

That’s always a good sign.

When I first heard about the Vintage Computer Festival Midwest, I almost immediately got the notion that I wanted to go. Besides the TRS-80 CoCo II up in my attic, I also have fond memories of an old IBM PC with CGA monitor, a 25MHz 486, an Alpha also in my attic, and a lot of other computers along the way. I didn’t really think my boys would be interested.

But I mentioned it to them, and they just lit up. They remembered the Youtube videos I’d shown them of old line printers and punch card readers, and thought it would be great fun. I thought it could be a great educational experience for them too — and it was.

It also turned into a trip that combined being a proud dad with so many of my other interests. Quite a fun time.

IMG_20160911_061456

(Jacob modeling his new t-shirt)

Captain Jacob

Chicago being not all that close to Kansas, I planned to fly us there. If you’re flying yourself, solid flight planning is always important. I had already planned out my flight using electronic tools, but I always carry paper maps with me in the cockpit for backup. I got them out and the boys and I planned out the flight the old-fashioned way.

Here’s Oliver using a scale ruler (with markings for miles corresponding to the scale of the map) and Jacob doing calculating for us. We measured the entire route and came to within one mile of the computer’s calculation for each segment — those boys are precise!

20160904_175519

We figured out how much fuel we’d use, where we’d make fuel stops, etc.

The day of our flight, we made it as far as Davenport, Iowa when a chance of bad weather en route to Chicago convinced me to land there and drive the rest of the way. The boys saw that as part of the exciting adventure!

Jacob is always interested in maps, and had kept wanting to use my map whenever we flew. So I dug an old Android tablet out of the attic, put Avare on it (which has aviation maps), and let him use that. He was always checking it while flying, sometimes saying this over his headset: “DING. Attention all passengers, this is Captain Jacob speaking. We are now 45 miles from St. Joseph. Our altitude is 6514 feet. Our speed is 115 knots. We will be on the ground shortly. Thank you. DING”

Here he is at the Davenport airport, still busy looking at his maps:

IMG_20160909_183813

Every little airport we stopped at featured adults smiling at the boys. People enjoyed watching a dad and his kids flying somewhere together.

Oliver kept busy too. He loves to help me on my pre-flight inspections. He will report every little thing to me – a scratch, a fleck of paint missing on a wheel cover, etc. He takes it seriously. Both boys love to help get the plane ready or put it away.

The Computers

Jacob quickly gravitated towards a few interesting things. He sat for about half an hour watching this old Commodore plotter do its thing (click for video):

VID_20160910_142044

His other favorite thing was the phones. Several people had brought complete analog PBXs with them. They used them to demonstrate various old phone-related hardware; one had several BBSs running with actual modems, another had old answering machines and home-security devices. Jacob learned a lot about phones, including how to operate a rotary-dial phone, which he’d never used before!

IMG_20160910_151431

Oliver was drawn more to the old computers. He was fascinated by the IBM PC XT, which I explained was just about like a model I used to get to use sometimes. They learned about floppy disks and how computers store information.

IMG_20160910_195145

He hadn’t used joysticks much, and found Pong (“this is a soccer game!”) interesting. Somebody has also replaced the guts of a TRS-80 with a Raspberry Pi running a SNES emulator. This had thoroughly confused me for a little while, and excited Oliver.

Jacob enjoyed an old TRS-80, which, through a modern Ethernet interface and a little computation help in AWS, provided an interface to Wikipedia. Jacob figured out the text-mode interface quickly. Here he is reading up on trains.

IMG_20160910_140524

I had no idea that Commodore made a lot of adding machines and calculators before they got into the home computer business. There was a vast table with that older Commodore hardware, too much to get on a single photo. But some of the adding machines had their covers off, so the boys got to see all the little gears and wheels and learn how an adding machine can do its printing.

IMG_20160910_145911

And then we get to my favorite: the big iron. Here is a VAX — a working VAX. When you have a computer that huge, it’s easier for the kids to understand just what something is.

IMG_20160910_125451

When we encountered the table from the Glenside Color Computer Club, featuring the good old CoCo IIs like what I used as a kid (and have up in my attic), I pointed out to the boys that “we have a computer just like this that can do these things” — and they responded “wow!” I think they are eager to try out floppy disks and disk BASIC now.

Some of my favorites were the old Unix systems, which are a direct ancestor to what I’ve been working with for decades now. Here’s AT&T System V release 3 running on its original hardware:

IMG_20160910_144923

And there were a couple of Sun workstations there, making me nostalgic for my college days. If memory serves, this one is actually running on m68k in the pre-Sparc days:

IMG_20160910_153418

Returning home

After all the excitement of the weekend, both boys zonked out for awhile on the flight back home. Here’s Jacob, sleeping with his maps still up.

IMG_20160911_132952

As we were nearly home, we hit a pocket of turbulence, the kind that feels as if the plane is dropping a bit (it’s perfectly normal and safe; you’ve probably felt that on commercial flights too). I was a bit concerned about Oliver; he is known to get motion sick in cars (and even planes sometimes). But what did I hear from Oliver?

“Whee! That was fun! It felt like a roller coaster! Do it again, dad!”