All posts by John Goerzen

A great day for a flight with the boys

June 27, 2016Aviation, FamilyJohn Goerzen

I tend to save up my vacation time to use in summer for family activities, and today was one of those days.

Yesterday, Jacob and Oliver enjoyed planning what they were going to do with me. They ruled out all sorts of things nearby, but they decided they would like to fly to Ponca City, explore the oil museum there, then eat at Enrique’s before flying home.

Of course, it is not particularly hard to convince me to fly somewhere. So off we went today for some great father-son time.

The weather on the way was just gorgeous. We cruised along at about a mile above ground, which gave us pleasantly cool air through the vents and a smooth ride. Out in the distance, a few clouds were trying to form.

Whether I’m flying or driving, a pilot is always happy to pass a small airport. Here was the Winfield, KS airport (KWLD):

This is a beautiful time of year in Kansas. The freshly-cut wheat fields are still a vibrant yellow. Other crops make a bright green, and colors just pop from the sky. A camera can’t do it justice.

They enjoyed the museum, and then Oliver wanted to find something else to do before we returned to the airport for dinner. A little exploring yielded the beautiful and shady Garfield Park, complete with numerous old stone bridges.

Of course, the hit of any visit to Enrique’s is their “ice cream tacos” (sopapillas with ice cream). Here is Oliver polishing off his.

They had both requested sightseeing from the sky on our way back, but both fell asleep so we opted to pass on that this time. Oliver slept through the landing, and I had to wake him up when it was time to go. I always take it as a compliment when a 6-year-old sleeps through a landing!

Most small airports have a bowl of candy setting out somewhere. Jacob and Oliver have become adept at finding them, and I will usually let them “talk me into” a piece of candy at one of them. Today, after we got back, they were intent at exploring the small gift shop back home, and each bought a little toy helicopter for $1.25. They may have been too tired to enjoy it though.

They’ve been in bed for awhile now, and I’m still smiling about the day. Time goes fast when you’re having fun, and all three of us were. It is fun to see them inheriting my sense of excitement at adventure, and enjoying the world around them as they go.

The lady at the museum asked how we had heard about them, and noticed I drove up in an airport car (most small airports have an old car you can borrow for a couple hours for free if you’re a pilot). I told the story briefly, and she said, “So you flew out to this small town just to spend some time here?” “Yep.” “Wow, that’s really neat. I don’t think we’ve ever had a visitor like you before.” Then she turned to the boys and said, “You boys are some of the luckiest kids in the world.”

And I can’t help but feel like the luckiest dad in the world.

I’m switching from git-annex to Syncthing

June 27, 2016Debian, Desktop Linux, LinuxJohn Goerzen

I wrote recently about using git-annex for encrypted sync, but due to a number of issues with it, I’ve opted to switch to Syncthing.

I’d been using git-annex with real but noncritical data. Among the first issues I noticed was occasional but persistent high CPU usage spikes, which once started, would persist apparently forever. I had an issue where git-annex tried to replace files I’d removed from its repo with broken symlinks, but the real final straw was a number of issues with the gcrypt remote repos. git-remote-gcrypt appears to have a number of issues with possible race conditions on the remote, and at least one of them somehow caused encrypted data to appear in a packfile on a remote repo. Why there was data in a packfile there, I don’t know, since git-annex is supposed to keep the data out of packfiles.

Anyhow, git-annex is still an awesome tool with a lot of use cases, but I’m concluding that live sync to an encrypted git remote isn’t quite there yet enough for me.

So I looked for alternatives. My main criteria were supporting live sync (via inotify or similar) and not requiring the files to be stored unencrypted on a remote system (my local systems all use LUKS). I found Syncthing met these requirements.

Syncthing is pretty interesting in that, like git-annex, it doesn’t require a centralized server at all. Rather, it forms basically a mesh between your devices. Its concept is somewhat similar to the proprietary Bittorrent Sync — basically, all the nodes communicate about what files and chunks of files they have, and the changes that are made, and immediately propagate as much as possible. Unlike, say, Dropbox or Owncloud, Syncthing can actually support simultaneous downloads from multiple remotes for optimum performance when there are many changes.

Combined with syncthing-inotify or syncthing-gtk, it has immediate detection of changes and therefore very quick propagation of them.

Syncthing is particularly adept at figuring out ways for the nodes to communicate with each other. It begins by broadcasting on the local network, so known nearby nodes can be found directly. The Syncthing folks also run a discovery server (though you can use your own if you prefer) that lets nodes find each other on the Internet. Syncthing will attempt to use UPnP to configure firewalls to let it out, but if that fails, the last resort is a traffic relay server — again, a number of volunteers host these online, but you can run your own if you prefer.

Each node in Syncthing has an RSA keypair, and what amounts to part of the public key is used as a globally unique node ID. The initial link between nodes is accomplished by pasting the globally unique ID from one node into the “add node” screen on the other; the user of the first node then must accept the request, and from that point on, syncing can proceed. The data is all transmitted encrypted, of course, so interception will not cause data to be revealed.

Really my only complaint about Syncthing so far is that, although it binds to localhost, the web GUI does not require authentication by default.

There is an ITP open for Syncthing in Debian, but until then, their apt repo works fine. For syncthing-gtk, the trusty version of the webupd8 PPD works in Jessie (though be sure to pin it to a low priority if you don’t want it replacing some unrelated Debian packages).

Mud, Airplanes, Arduino, and Fun

June 15, 2016Children & Computing, Family, Hardware, TravelJohn Goerzen

The last few weeks have been pretty hectic in their way, but I’ve also had the chance to take some time off work to spend with family, which has been nice.

Memorial Day: breakfast and mud

For Memorial Day, I decided it would be nice to have a cookout for breakfast rather than for dinner. So we all went out to the fire ring. Jacob and Oliver helped gather kindling for the fire, while Laura chopped up some vegetables. Once we got a good fire going, I cooked some scrambled eggs in a cast iron skillet, mixed with meat and veggies. Mmm, that was tasty.

Then we all just lingered outside. Jacob and Oliver enjoyed playing with the cats, and the swingset, and then…. water. They put the hose over the slide and made a “water slide” (more mud slide maybe).

Then we got out the water balloon fillers they had gotten recently, and they loved filling up water balloons. All in all, we all just enjoyed the outdoors for hours.

Flying to Petit Jean, Arkansas

Somehow, neither Laura nor I have ever really been to Arkansas. We figured it was about time. I had heard wonderful things about Petit Jean State Park from other pilots: it’s rather unique in that it has a small airport right in the park, a feature left over from when Winthrop Rockefeller owned much of the mountain.

And what a beautiful place it was! Dense forests with wonderful hiking trails, dotted with small streams, bubbling springs, and waterfalls all over; a nice lake, and a beautiful lodge to boot. Here was our view down into the valley at breakfast in the lodge one morning:

And here’s a view of one of the trails:

The sunset views were pretty nice, too:

And finally, the plane we flew out in, parked all by itself on the ramp:

It was truly a relaxing, peaceful, re-invigorating place.

Flying to Atchison

Last weekend, Laura and I decided to fly to Atchison, KS. Atchison is one of the oldest cities in Kansas, and has quite a bit of history to show off. It was fun landing at the Amelia Earhart Memorial Airport in a little Cessna, and then going to three museums and finding lunch too.

Of course, there is the Amelia Earhart Birthplace Museum, which is a beautifully-maintained old house along the banks of the Missouri River.

I was amused to find this hanging in the county historical society museum:

One fascinating find is a Regina Music Box, popular in the late 1800s and early 1900s. It operates under the same principles as those that you might see that are cylindrical. But I am particular impressed with the effort that would go into developing these discs in the pre-computer era, as of course the holes at the outer edge of the disc move faster than the inner ones. It would certainly take a lot of careful calculation to produce one of these. I found this one in the Cray House Museum:

An Arduino Project with Jacob

One day, Jacob and I got going with an Arduino project. He wanted flashing blue lights for his “police station”, so we disassembled our previous Arduino project, put a few things on the breadboard, I wrote some code, and there we go. Then he noticed an LCD in my Arduino kit. I hadn’t ever gotten around to using it yet, and of course he wanted it immediately. So I looked up how to connect it, found an API reference, and dusted off my C skills (that was fun!) to program a scrolling message on it. Here is Jacob showing it off:

How git-annex replaces Dropbox + encfs with untrusted providers

June 6, 2016UncategorizedJohn Goerzen

git-annex has been around for a long time, but I just recently stumbled across some of the work Joey has been doing to it. This post isn’t about it’s traditional roots in git or all the features it has for partial copies of large data sets, but rather for its live syncing capabilities like Dropbox. It takes a bit to wrap your head around, because git-annex is just a little different from everything else. It’s sort of like a different-colored smell.

The git-annex wiki has a lot of great information — both low-level reference and a high-level 10-minute screencast showing how easy it is to set up. I found I had to sort of piece together the architecture between those levels, so I’m writing this all down hoping it will benefit others that are curious.

Ir you just want to use it, you don’t need to know all this. But I like to understand how my tools work.

Overview

git-annex lets you set up a live syncing solution that requires no central provider at all, or can be used with a completely untrusted central provider. Depending on your usage pattern, this central provider could require only a few MBs of space even for repositories containing gigabytes or terabytes of data that is kept in sync.

Let’s take a look at the high-level architecture of the tool. Then I’ll illustrate how it works with some scenarios.

Three Layers

Fundamentally, git-annex takes layers that are all combined in Dropbox and separates them out. There is the storage layer, which stores the literal data bytes that you are interested in. git-annex indexes the data in storage by a hash. There is metadata, which is for things like a filename-to-hash mapping and revision history. And then there is an optional layer, which is live signaling used to drive the real-time syncing.

git-annex has several modes of operation, and the one that enables live syncing is called the git-annex assistant. It runs as a daemon, and is available for Linux/POSIX platforms, Windows, Mac, and Android. I’ll be covering it here.

The storage layer

The storage layer simply is blobs of data. These blobs are indexed by a hash, and can be optionally encrypted at rest at remote backends. git-annex has a large number of storage backends; some examples include rsync, a remote machine with git-annex on it that has ssh installed, WebDAV, S3, Amazon Glacier, removable USB drive, etc. There’s a huge list.

One of the git-annex features is that each client knows the state of each storage repository, as well as the capability set of each storage repository. So let’s say you have a workstation at home and a laptop you take with you to work or the coffee shop. You’d like changes on one to be instantly recognized on another. With something like Dropbox or OwnCloud, every file in the set you want synchronized has to reside on a server in the cloud. With git-annex, it can be configured such that the server in the cloud only contains a copy of a file until every client has synced it up, at which point it gets removed. Think about it – that is often what you want anyhow, so why maintain an unnecessary copy after it’s synced everywhere? (This behavior is, of course, configurable.) git-annex can also avoid storing in the cloud entirely if the machines are able to reach each other directly at least some of the time.

The metadata layer

Metadata about your files includes a mapping from the file names to the storage location (based on hashes), change history, and information about the status of each machine that participates in the syncing. On your clients, git-annex stores this using git. This detail is very useful to some, and irrelevant to others.

Some of the git-annex storage backends can support only storage (S3, for instance). Some can support both storage and metadata (rsync, ssh, local drives, etc.) You can even configure a backend to support only metadata (more on why that may be useful in a bit). When you are working with a git-backed repository for git-annex, it can hold data, metadata, or both.

So, to have a working sync system, you must have a way to transport both the data and the metadata. The transport for the metadata is generally rsync or git, but it can also be XMPP in which Git changesets are basically wrapped up in XMPP presence messages. Joey says, however, that there are some known issues with XMPP servers sometimes dropping or reordering some XMPP messages, so he doesn’t encourage that method currently.

The live signaling layer

So once you have your data and metadata, you can already do syncs via git annex sync --contents. But the real killer feature here will be automatic detection of changes, both on the local and the remote. To do that, you need some way of live signaling. git-annex supports two methods.

The first requires ssh access to a remote machine where git-annex is installed. In this mode of operation, when the git-annex assistant fires up, it opens up a persistent ssh connection to the remote and runs the git-annex-shell over there, which notifies it of changes to the git metadata repository. When a change is detected, a sync is initiated. This is considered ideal.

A substitute can be XMPP, and git-annex actually converts git commits into a form that can be sent over XMPP. As I mentioned above, there are some known reliability issues with this and it is not the recommended option.

Encryption

When it comes to encryption, you generally are concerned about all three layers. In an ideal scenario, the encryption and decryption happens entirely on the client side, so no service provider ever has any details about your data.

The live signaling layer is encrypted pretty trivially; the ssh sessions are, of course, encrypted and TLS support in XMPP is pervasive these days. However, this is not end-to-end encryption; those messages are decrypted by the service provider, so a service provider could theoretically spy on metadata, which may include change times and filenames, though not the contents of files themselves.

The data layer also can be encrypted very trivially. In the case of the “dumb” backends like S3, git-annex can use symmetric encryption or a gpg keypair and all that ever shows up on the server are arbitrarily-named buckets.

You can also use a gcrypt-based git repository. This can cover both data and metadata — and, if the target also has git-annex installed, the live signalling layer. Using a gcrypt-based git repository for the metadata and live signalling is the only way to accomplish live syncing with 100% client-side encryption.

All of these methods are implemented in terms of gpg, and can support symmetric of public-key encryption.

It should be noted here that the current release versions of git-annex need a one-character patch in order to fix live syncing with a remote using gcrypt. For those of you running jessie, I recommend the version in jessie-backports, which is presently 5.20151208. For your convenience, I have compiled an amd64 binary that can drop in over /usr/bin/git-annex if you have this version. You can download it and a gpg signature for it. Note that you only need this binary on the clients; the server can use the version from jessie-backports without issue.

Putting the pieces together: some scenarios

Now that I’ve explained the layers, let’s look at how they fit together.

Scenario 1: Central server

In this scenario, you might have a workstation and a laptop that sync up with each other by way of a central server that also has a full copy of the data. This is the scenario that most closely resembles Dropbox, box, or OwnCloud.

Here you would basically follow the steps in the git-assistant screencast: install git-annex on a server somewhere, and point your clients to it. If you want full end-to-end encryption, I would recommend letting git-annex generate a gpg keypair for you, which you would then need to copy to both your laptop and workstation (but not the server).

Every change you make locally will be synced to the server, and then from the server to your other PC. All three systems would be configured in the “client” transfer group.

Scenario 1a: Central server without a full copy of the data

In this scenario, everything is configured the same except the central server is configured with the “transfer” transfer group. This means that the actual data synced to it is deleted after it has been propagated to all clients. Since git-annex can verify which repository has received a copy of which data, it can easily enough delete the actual file content from the central server after it has been copied to all the clients. Many people use something like Dropbox or OwnCloud as a multi-PC syncing solution anyhow, so once the files have been synced everywhere, it makes sense to remove them from the central server.

This is often a good ideal for people. There are some obvious downsides that are sometimes relevant. For instance, to add a third sync client, it must be able to initially copy down from one of the existing clients. Or, if you intend to access the data from a device such as a cell phone where you don’t intend for it to have a copy of all data all the time, you won’t have as convenient way to download your data.

Scenario 1b: Split data/metadata central servers

Imagine that you have a shell or rsync account on some remote system where you can run git-annex, but don’t have much storage space. Maybe you have a cheap VPS or shell account somewhere, but it’s just not big enough to hold your data.

The answer to this would be to use this shell or rsync account for the metadata, but put the data elsewhere. You could, for instance, store the data in Amazon S3 or Amazon Glacier. These backends aren’t capable of storing the git-annex metadata, so all you need is a shell or rsync account somewhere to sync up the metadata. (Or, as below, you might even combine a fully distributed approach with this.) Then you can have your encrypted data pushed up to S3 or some such service, which presumably will grow to whatever size you need.

Scenario 2: Fully distributed

Like git itself, git-annex does not actually need a central server at all. If your different clients can reach each other directly at least some of the time, that is good enough. Of course, a given client will not be able to do fully automatic live sync unless it can reach at least one other client, so changes may not propagate as quickly.

You can simply set this up by making ssh connections available between your clients. git-annex assistant can automatically generate appropriate ~/.ssh/authorized_keys entries for you.

Scenario 2a: Fully distributed with multiple disconnected branches

You can even have a graph of connections available. For instance, you might have a couple machines at home and a couple machines at work with no ability to have a direct connection between them (due to, say, firewalls). The two machines at home could sync with each other in real-time, as could the two machines at work. git-annex also supports things like USB drives as a transport mechanism, so you could throw a USB drive in your pocket each morning, pop it in to one client at work, and poof – both clients are synced up over there. Repeat when you get home in the evening, and you’re synced there. The USB drive’s repository can, of course, be of the “transport” type so data is automatically deleted from it once it’s been synced everywhere.

Scenario 3: Hybrid

git-annex can support LAN sync even if you have a central server. If your laptop, say, travels around but is sometimes on the same LAN as your PC, git-annex can easily sync directly between the two when they are reachable, saving a round-trip to the server. You can assign a cost to each remote, and git-annex will always try to sync first to the lowest-cost path that is available.

Drawbacks of git-annex

There are some scenarios where git-annex with the assistant won’t be as useful as one of the more traditional instant-sync systems.

The first and most obvious one is if you want to access the files without the git-annex client. For instance, many of the other tools let you generate a URL that you can email to people, and then they can download files without any special client software. This is not directly possible with git-annex. You could, of course, make something like a public_html directory be managed with git-annex, but it wouldn’t provide things like obfuscated URLs, password-protected sharing, time-limited sharing, etc. that you get with other systems. While you can share your repositories with others that have git-annex, you can’t share individual subdirectories; for a given repository, it is all or nothing.

The Android client for git-annex is a pretty interesting thing: it is mostly a small POSIX environment, providing a terminal, git, gpg, and the same web interface that you get on a standalone machine. This means that the git-annex Android client is fully functional compared to a desktop one. It also has a quick setup process for syncing off your photos/videos. On the other hand, the integration with the Android ecosystem is poor compared to most other tools.

Other git-annex features

git-annex has a lot to offer besides the git-annex assistant. Besides the things I’ve already mentioned, any given git-annex repository — including your client repository — can have a partial copy of the full content. Say, for instance, that you set up a git-annex repository for your music collection, which is quite large. You want some music on your netbook, but don’t have room for it all. You can tell git-annex to get or drop files from the netbook’s repository without deleting them remotely. git-annex has quite a few ways to automate and configure this, including making sure that at least a certain number of copies of a file exist in your git-annex ecosystem.

Conclusion

I initially started looking at git-annex due to the security issues with encfs, and the difficulty with setting up ecryptfs in this way. (I had been layering encfs atop OwnCloud). git-annex certainly ticks the box for me security-wise, and obviously anything encrypted with encfs wasn’t going to be shared with others anyhow. I’ll be using git-annex more in the future, I’m sure.

Update 2016-06-27: I had some issues with git-annex in this configuration.

That was satisfying

May 30, 2016UncategorizedJohn Goerzen

It’s been awhile due to all sorts of other stuff going on. Nice to see this clogging my inbox again:

It really is satisfying to close bugs!

The Simple Joys of the Plains

May 8, 2016Aviation, FamilyJohn Goerzen

We love to go exploring as a family. Last year, we gave Jacob and Oliver a theme: “find places older than Grandpa.” They got creative really quick, realizing that any state park counts (“dirt is older than grandpa!”) as did pretty much any museum. Probably our hit from last year was the visit to the tunnels under Ellinwood, KS.

Beatrice, NE

This year, our theme is “places we can fly to”. A couple of weeks ago, Laura had a conference in the beautiful small town of Beatrice, NE. So all four of us flew up, and Jacob, Oliver, and I found fun activities while Laura was at her conference.

We walked around Beatrice a bit, and I noticed this rails-to-trails area. Jacob and Oliver were immediately interested (since it was railroad-related). They quickly turned it into a game of kick-the-dandelion, trying to kick dandelions off their stems and see how high in the air they could get them. The answer: pretty high.

Of course, you can’t go wrong with swimming. Here’s Oliver getting ready for some swimming.

Right near Beatrice is the Homestead National Monument. Of course, the bales decorated like a minion got their attention.

Like the other national parks, this one has a junior ranger program. You complete a few things in an activity book and take a pledge to protect the park, and then you get a badge and some stickers. Here’s Oliver proudly taking his pledge, holding the new raccoon he bought in their gift shop.

Canyon, TX

Laura and I have been to Canyon, TX, twice — the first was for our honeymoon. Yes, we did get some strange looks when we told people we were going to Amarillo for our honeymoon. But it was absolutely perfect for us. We both enjoy the simple gifts of nature.

We kept thinking “we’ve got to take the boys here”. So this weekend, we did. We flew a Cessna out there.

Almost every little general aviation airport seems to have a bowl of candy, a plate of cookies, or some such thing for people that are flying through. I often let Jacob and Oliver choose ONE item.

They hit the jackpot when we stopped at West Woodward, Oklahoma for fuel and a break. Two whole fridges stocked with stuff: cans of pop in one, and all sorts of snacks in the other. In typical GA fashion, there was a jar in the fridge asking for $1 if you took something. And it clearly hadn’t been emptied in awhile.

They also had a nice lounge and a patio. Perfect for munching while watching the activities on the ramp.

After landing at the beautiful little Tradewind Airport in Amarillo, we ate dinner at Feldman’s Wrong-Way Diner in Canyon, TX. Oh my, was that ever popular with the boys.

The eagerly looked around to find anything that was “wrong” — a plane hanging upside down from the ceiling, a direction sign saying “Tattoine – 30 parsecs”, movie posters hung upside down, whatever it might be. The fact that model trains were whirring past overhead certainly didn’t hurt either.

They had a giant bin of crayons by the entrance. Jacob and Oliver each grabbed a fistful, and decided it would be fun to do some math problems while we wait. Oliver particularly got into that, and was quite accurate on his large addition problems. Impressive for a first-grader!

Of course, the big highlight of the area is Palo Duro Canyon. Jacob and Oliver were so eager to explore the canyon that they were just about bubbling over with excitement the night before. They decided that we should explore one of the most difficult trails in the canyon – one that would take us from the bottom of the canyon all the way to the top and back, about 2.5 miles each way.

And they LOVED it. We’d stop every few minutes to climb on some rocks, smash up some pieces of sandstone, munch on a snack, or even watch a lizard scurry past.

At the “trading post” in the canyon, both boys explored the gift shop. Jacob happily purchased a Texas magnet and Palo Duro Canyon keychain, which he carried around the rest of the weekend. Oliver loves stuffed animals, and he bought a cuddly little (but long) snake. When we got back to the hotel, he tied a couple of knots in it, and it became “snake airlines”. Here is the snake airline taking off.

He named it “Rattletail the friendly snake”, which I thought was a pretty nifty name.

The hotel’s waffle maker made Texas-shaped waffles, clearly a hit!

Saturday, we explored the absolutely massive Panhandle-Plains Historical Museum. (How does something that huge wind up in Canyon, TX?) Both boys enjoyed spending hours there. Here’s Oliver in Pioneer Town (an indoor recreation of a 1900s town) sending a telegraph message.

Oliver wanted to help with the plane. He helped me tie it down in Amarillo, helped check it over during preflight, basically got involved in every part of it. Jacob studied aviation maps (sectionals) with me, planning our flight, figuring out how fast we’d go. I loaded Avare (an Android app) on an old tablet for him, so he had aviation maps in the cockpit just like me. He would be telling us how fast we were going every so often, pointing out landmarks, etc.

When it was time to head back home, both boys wanted to stay longer — a sure sign of a good trip. They wanted to hike another trail in the canyon, go back to the museum, and “eat at Feldman’s 18 more times.” (We got there twice, which was plenty for Laura and me!)

On our drive home, Oliver said, “Dad-o, will you teach me to be a pilot? You should be my flight instructor. Then I could fly everywhere with you.”

Now that just makes a dad’s day.

Count me as a systemd convert

April 21, 2016DebianJohn Goerzen

Back in 2014, I wrote about some negative first impressions of systemd. I also had a plea to debian-project to end all the flaming, pointing out that “jessie will still boot”, noting that my preference was for sysvinit but things are what they are and it wasn’t that big of a deal.

Although I still have serious misgivings about the systemd upstream’s attitude, I’ve got to say I find the system rather refreshing and useful in practice.

Here’s an example. I was debugging the boot on a server recently. It mounts a bunch of NFS filesystems and runs a third-party daemon that is started from an old-style /etc/init.d script.

We had a situation where the NFS filesystems the daemon required didn’t mount on boot. The daemon then was started, and unfortunately it basically does a mkdir -p on startup. So it started running and processing requests with negative results.

So there were two questions: why did the NFS filesystems fail to start, and how could we make sure the daemon wouldn’t start without them mounted? For the first, journalctl -xb was immensely helpful. It logged the status of each individual mount, and it turned out that it looked like a modprobe or kernel race condition when a bunch of NFS mounts were kicked off in parallel and all tried to load the nfsv4 module at the same time. That was easy enough to work around by adding nfsv4 to /etc/modules. Now for the other question: refusing to start the daemon if the filesystems weren’t there.

With systemd, this was actually trivial. I created /etc/systemd/system/mydaemon.service.requires (I’ll call the service “mydaemon” here), and in it I created a symlink to /lib/systemd/system/remote-fs.target. Then systemctl daemon-reload, and boom, done. systemctl list-dependencies mydaemon will even show the the dependency tree, color-coded status of each item on it, and will actually show every single filesystem that remote-fs requires and the status of it in one command. Super handy.

In a non-systemd environment, I’d probably be modifying the init script and doing a bunch of manual scripting to check the filesystems. Here, one symlink and one command did it, and I get tools to inspect the status of the mydaemon prerequisites for free.

I’ve got to say, as someone that has occasionally had to troubleshoot boot ordering and update-rc.d symlink hell, troubleshooting this stuff in systemd is considerably easier and the toolset is more powerful. Yes, it has its set of poorly-documented complexity, but then so did sysvinit.

I never thought the “world is falling” folks were right, but by now I can be counted among those that feels like systemd has matured to the point where it truly is superior to sysvinit. Yes, in 2014 it had some bugs, but by here in 2016 it looks pretty darn good and I feel like Debian’s decision has been validated through my actual experience with it.

A Year of Flight

April 15, 2016AviationJohn Goerzen

“Dad-o, I’m so glad you’re a pilot!”

My 9-year-old son Jacob has been saying that, always with a big hug and his fond nickname for me (“dad-o”). It has now been a year since the first time I sat in the pilot’s seat of a plane, taking my first step towards exploring the world from the sky. And now, one year after I first sat in the pilot’s seat of an airborne plane, it’s prompted me to think back to my own memories.

Flying over the airport at Moundridge, KS

Memories

Back when I was a child, maybe about the age my children are now, I’d be outside in the evening and see this orange plane flying overhead. Our neighbor Don had a small ultralight plane and a grass landing strip next to his house. I remember longing to be up in the sky with Don, exploring the world from up there. At that age, I didn’t know all the details of why that wouldn’t work — I just knew I wanted to ride in it.

It wasn’t until I was about 11 that I flew for the first time. I still remember that TWA flight with my grandma, taking off early in the morning and flying just a little ways above the puffy clouds lit up all yellow and orange by the sunrise. Even 25 years later, that memory still holds as one of the most beautiful scenes I have ever seen.

Exploring

I have always been an explorer.

When I go past something interesting, I love to go see what it looks like inside. I enjoy driving around Kansas with Laura, finding hidden waterfalls, old county courthouses, ghost towns, beautiful old churches, even small-town restaurants. I explore things around me, too — once taking apart a lawnmower engine as a child, nowadays building HF antennas in my treetops or writing code for Linux. If there is little to learn about something, it becomes less interesting to me.

I see this starting to build in my children, too. Since before they could walk, if we were waiting for something in a large building, we’d “go exploring.”

A patch of rain over Hillsboro, KS

The New World

A pilot once told me, “Nobody can become a pilot without it changing the way they see the world — and then, changing their life.”

I doubted that. But it was true. One of the most poetic sights I know is flying a couple thousand feet above an interstate highway at night, following it to my destination. All those red and white lights, those metal capsules of thousands of lives and thousands of stories, stretching out as far as the eye can see in either direction.

Kansas sunset from the plane

When you’re in a plane, that small town nowhere near a freeway that always seemed so far away suddenly is only a 15-minute flight away, not even enough time to climb up to a high cruise altitude. Two minutes after takeoff, any number of cities that are an hour’s drive away are visible simultaneously, their unique features already recognizable: a grain elevator, oil refinery, college campus, lake, whatever.

And all the houses you fly over — each with people in them. Some pretty similar to you, some apparently not. But pretty soon you realize that we all are humans, and we aren’t all that different. You can’t tell a liberal from a conservative from the sky, nor a person’s race or religion, nor even see the border between states. Towns and cities are often nameless from the sky, unless you’re really low; only your navigation will tell you where you are.

I’ve had the privilege to fly to small out-of-the-way airports, the kind that have a car that pilots can use for free to go into town and get lunch, and leave the key out for them. There I’ve met many friendly people. I’ve also landed my little Cessna at a big commercial airport where I probably used only 1/10th of the runway, on a grass runway that was barely maintained at all. I’ve flown to towns I’d driven to or through many times, discovering the friendly folks at the small airport out of town. I’ve flown to parts of Kansas I’ve never been to before, discovered charming old downtowns and rolling hills, little bursts of rain and beautiful sunsets that seem to turn into a sea.

Parked at the Smith Center, KS airport terminal, about to meet some wonderful people

For a guy that loves exploring the nooks and crannies of the world that everyone else drives by on their way to a major destination, being a pilot has meant many soul-filling moments.

Hard Work

I knew becoming a pilot would be a lot of hard work, and thankfully I remembered stories like that when I finally concluded it would be worth it. I found that I had an aptitude for a lot of things that many find difficult about being a pilot: my experience with amateur radio made me a natural at talking to ATC, my fascination with maps and navigation meant I already knew how to read aviation sectional maps before I even started my training and knew how to process that information in the cockpit, my years as a system administrator and programmer trained me with a careful and methodical decision-making process. And, much to the surprise of my flight instructor, I couldn’t wait to begin the part of training about navigating using VORs (VHF radio beacons). I guess he, like many student pilots, had struggled with that, but I was fascinated by this pre-GPS technology (which I still routinely use in my flight planning, as a backup in case the GPS constellation or a GPS receiver fails). So that left the reflexes of flight, the “art” of it, as the parts I had to work on the hardest.

The exam with the FAA is not like getting your driver’s license. It’s a multi-stage and difficult process. So when the FAA Designated Pilot Examiner said “congratulations, pilot!” and later told my flight instructor that “you did a really good job with this one,” I felt a true sense of accomplishment.

Some of my prep materials

Worth It

Passengers in a small plane can usually hear all the radio conversations going on. My family has heard me talking to air traffic control, to small and big planes. My 6-year-old son Oliver was playing yesterday, and I saw him pick up a plane and say this:

“Two-four-niner-golf requesting to land on runway one-seven…. Two-four-niner-golf back-taxi on one-seven… Two-four-niner-golf ready to takeoff on runway one-seven!”

That was a surprisingly accurate representation of some communication a pilot might have (right down to the made-up tailnumber with the spelling alphabet!)

It just got more involved from there!

Jacob and Oliver love model train shows. I couldn’t take them to one near us, but there was one in Joplin, MO. So the day before Easter, while Laura was working on her Easter sermon, two excited boys and I (frankly also excited) climbed into a plane and flew to Joplin.

We had a great time at the train show, discovered a restaurant specializing in various kinds of hot dogs (of course they both wanted to eat there), played in a park, explored the city, and they enjoyed the free cookies at the general aviation terminal building while I traded tips on fun places to fly with other pilots.

When it comes right down to it, the smiles of the people I fly with are the most beautiful thing in the air.

Jacob after his first father-son flight with me

Free cars, sunsets, and Kansas

March 23, 2016Aviation, Family, TravelJohn Goerzen

“Will you have a car I can borrow?” I asked.

“Sure. No charge. There’s a sign telling you where to find the key.”

It is pretty common for small airports to have a car for a pilot to borrow when flying in. This lets a person go into town for lunch, or visit friends. And it’s usually free, with a can to donate a few bucks or a polite request to fill up the tank when you’re done.

Still, when I had called ahead to ask about flying into the airport in a small town in north-central Kansas, I hadn’t expected to be told to just waltz into the place and take the key. But they had no staff at the airport most of the time. So, to me — another person from a small town — it made perfect sense. Somehow, because of that phone call, this town I had visited once, maybe 25 years ago, seemed instantly familiar.

My mom grew up in a small town near there. She wanted me to see where she grew up, to meet some people that meant a lot to her. As it’s quite a distance from home, I offered to fly her there. So, Laura, mom, and I climbed into a Cessna one morning for the flight northwest. We touched down at the airport, and I pulled the plane up to the little terminal building.

After I took care of parking the plane, I went to find the car. Except the car was missing. Some other pilot had flown in the same day and was using it, according to the logbook on the desk. I called the number on a sign — which rang to the sheriff’s office — and they confirmed it. According to the logbook, this was only the third time that car had been driven since Thanksgiving. Were we stuck at the airport a few miles out of down?

Nope. Mom called the people we were going to meet, a wonderful couple in their upper 80s. They drove out to pick us up. I’m rather glad the car was gone, because I had such a great time visiting with them. Norris told me about the days when the state highways were gravel — how they’d have to re-blade them every few days due to all the traffic. I heard about what happened when the people in that community heard of some folks in Africa in need of car equipment — they modified a tractor to fit in a shipping container and shipped it to Africa, along with a lot of books, blankets, supplies, and anything else needed to fill up a huge shipping container. Sounds like something people around here would do.

We drove around a couple of the small towns. The town my mom grew up in has seen better days. Its schools closed years ago, the old hotel whose owner gave her piano lessons is condemned, and many houses have been lost. But the town lives on. A new community center was built a few years ago. The grain elevator is expanding. Every time a business on Main Street closes, the grocery store expands a little bit: it’s now a grocery store with a little hardware store and a little restaurant mixed in. “The mall”, as the locals jokingly call it. And, of course, two beautiful small churches still meet every Sunday. Here’s the one my mom attended as a child.

We drove past the marker at the geographic center of the contiguous United States. Norris saw some other visitors, rolled down his windows, and treated them — and us — to an unexpected story of the time thousands of people banded together to completely build a house in a single day, just down the road. Smiles all around.

So here I was, nearly 200 miles from home, in an unfamiliar town – but one where I could just feel the goodness. After spending a few hours with these people, I felt like they were old friends.

As I flew us home, I spotted one of my favorite Kansas sights: a beautiful sunset. From the plane, it almost looks like the land at the horizon turns blue like the ocean, and above it the last hint of sun paints the canvas-sky.

In this week of controversy, politics, and reports of violence, it reminds me that we all get the privilege of sharing this beautiful Earth. I didn’t ask anybody on that trip about their politics, religion, or opinions on any of the divisive issues of the day. Whether they agree with me on those things or not is irrelevant. I got to spend a day with good-hearted and delightful people, so I flew back with a smile.

Bach, Dot Matrix Printers, and Dinner

January 27, 2016Children & Computing, Family, HardwareJohn Goerzen

Dinner last night started out all normal. Then Jacob and Oliver started asking me about printers. First they wanted to know how an ink jet printer works. Then they wanted to know how a laser printer works. Then they wanted to know what would happen if you’d put ink in a laser printer or toner in an ink jet. They were fascinated as I described the various kinds of clogging and ruining that would inevitably occur.

Then these words: “What other kinds of printers are there?”

So our dinner conversation started to resolve around printers. I talked about daisy wheel printers, line printers, dot matrix printers. I explained the type chain of line printers, the pins of dot matrix. “More printers!” I had to dig deeper into my memory: wax transfer printers, thermal printers, dye sublimation, always describing a bit about how each one worked — except for dye sublimation, which I couldn’t remember many details about. “More printers!” So we went onwards towards the printing press, offset printing, screen printing, mimeograph, and photocopiers. Although I could give them plenty of details about most of the printers, I also failed under their barrage of questions about offset printing. So I finally capitulated, and said “should I go get my phone and look it up while you finish eating?” “YEAH!”

So I looked up the misty details of dye sublimation and offset printing and described how they worked. That seemed to satisfy them. Then they asked me what my favorite kind of printer was. I said “dot matrix, because it makes the best sound.” That had their attention. They stopped eating to ask the vitally important question: “Dad, what sound does it make?” At this point, I did my best dot matrix impression at the dinner table, to much laughter and delight.

Before long, they wanted to see videos of dot matrix printers. They were fascinated by them. And then I found this gem of a dot matrix printer playing a famous Bach tune, which fascinated me also:

I guess it must have all sunk in, because this morning before school Jacob all of a sudden begged to see the fuser in my laser printer. So we turned it around, opened up the back panel — to his obvious excitement — and then I pointed to the fuser, with its “hot” label. I even heard a breathy “wow” from him.

The Changelog

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