最近の発見

ここ何年もずっと同じところに住んでるけど、ここ最近でした発見が2件もあって、いつでも世界は新しい情報を渡してくれるなと思った。

まずは近くの高台から空気が澄んだ日の夕焼けの逆行で富士山(の輪郭)が見える。山頂の方しか見えないから、想像するような富士山じゃなく「えっそんなに山頂平だっけ?」と思いそうになるような富士山(案外平です)。その形状だから最初に見たときに目を疑ったけど方向と剣ヶ峰の尖りで間違いない。

そして背景(西方面)が曇っていると逆に田無タワーがはっきり見えることも最近の発見。前職でよく青梅街道の西遊記運転していつも前方の田無タワーが印象的だったが、住宅街からは普段見えない。ただしある(朝のジョギングで毎日のように通る)橋から見るとちょうど見える。最初気づいたのは(同じ方向に高圧電線も見えるから)形じゃなくその頂点の白いライトで、そこからよく見ると実は田無タワーの特徴的なあの形がお見え。

こうしてウン年住んでもまだ新しい発見があるから、新しいこと探す目を失わないようにね…


Adding Grafana annotations based on Argo CD events

I was thinking about how nice it would be if I could see on my main Grafana dashboard (the only one I use at this point actually) when there are new versions of something deployed. This way if by chance there is a problem with something afterwards I can see at a glance what could have gone wrong. Also I really like just looking at that Grafana dashboard and see that everything is alive and well. (Except when it isn’t.)

The Grafana chart was upgraded! Nice CPU burn…

Getting advanced mountain gear in Japan

You’d expect that with Japanese people being among the top mountaineers on 8000 peaks, the country having a healthy scene for winter sports it shouldn’t be hard to get advanced mountain gear, right? Let’s share some stories.


What was and what’s to come

I’ve already written about what was going on most of last year in my birthday post, but so many people around me are writing year-end/year-start summaries that nudged me to revisit the topic as well.

Budapest at night

Fighting an “Unknown MySQL error” when connecting to Aurora from Rails

The other day I was struggling with a very weird error when upgrading to Ruby 3. The initial migrations for a Rails app would fail with “Mysql2::Error: Unknown MySQL error (ActiveRecord::StatementInvalid)”, but only in certain environments. The error would occur when Rails tried to check what migrations are already applied by looking at the schema_migrations table.

2022-01-19 09:12:59.205 +0000 [DEBUG]    (1.7ms)  SELECT GET_LOCK('4252831219231700070', 0)
/usr/local/bundle/gems/mysql2-0.5.3/lib/mysql2/client.rb:131: warning: rb_tainted_str_new_cstr is deprecated and will be removed in Ruby 3.2
2022-01-19 09:12:59.222 +0000 [DEBUG]    (2.0ms)  SELECT `schema_migrations`.`version` FROM `schema_migrations` ORDER BY `schema_migrations`.`version` ASC
2022-01-19 09:12:59.224 +0000 [DEBUG]    (1.8ms)  SELECT RELEASE_LOCK('4252831219231700070')
rails aborted!
ActiveRecord::StatementInvalid: Mysql2::Error: Unknown MySQL error
/usr/local/bundle/gems/mysql2-0.5.3/lib/mysql2/client.rb:131:in `_query'

検疫所が指定する宿泊施設とは

日本に戻った。簡単じゃなかった。

向こう滞在中に国がオミクロン危険地区みたいな指定食らってしまって、日本に戻るとPCR検査いくらあってもワクチンいくら打ってても問答無用で指定施設に数日いないといけない。意味不明。

到着は成田だったのでその付近のホテルが宿泊施設として指定された。ホテルの館一つまるごとがその目的に割り当てられてるっぽくて貸し切り状態。とはいえ受付済んで部屋に入ったら部屋から出られなくなるから、一階にコンビニがあってもモンエナ買いにいけずつらかった。


When I accidentally Longhorn CSI

Symptoms: CPU load on all the nodes, but not the pods. Looking at Grafana, I noticed that CPU load on some of my nodes was constantly very high. At the same time, even the total CPU use of all the pods summed wasn’t above 0.4. What gives? This usually gives that the control plane is getting fried by something. It may be trying to relieve disk pressure, or in this case, trying to revive CSI.

Trying to figure out what was causing problems I checked the pods in kube-system with kubectl get pods -n kube-system. It quickly became apparent that there is a problem: disk-related pods like csi-resizer, csi-snapsotter and csi-provisioner were in CrashLoopBackOff.

I’ll be quite honest in that I’m not sure what the problem was. A few searches later I came to the conclusion that an earlier node reboot had left the pods with a corrupted DNS cache or something along those lines. Basically every issue I found with the symptoms I was seeing came down to DNS problems (longhorn/longhorn#2225, longhorn/longhorn#3109, rancher/k3os#811).

Alas I haven’t touched any of the networking machinery of Kubernetes (nor configured any of it for k3s) so my first idea was just the good old one from IT Crowd: “have you tried turning it off and on again?” So I did. Luckily another restart of the afflicted nodes solved the issue. I’m glad it did because I dread what I’d have had to do otherwise.


Steps to a more stable k3s cluster

It’s all too easy to kill a k3s cluster. I’ve been using k3s for years now and I’ve had plenty of adventures tweaking various aspects of running it. Before it’d take just a small change to an Argo Application to trigger a cascading failure. Hopefully now it’s a bit more resilient. Just a bit.

ship helm

PDF export with the Ruby 3.0.3 docker image

You might happen to use the wicked_pdf gem for PDF output in your Rails app. You might happen to use the wkhtmltopdf-binary gem to provide the required binaries. You might want to get the above to work on the latest (at this point 3.0.3-bullseye) Ruby docker image. Short answer: give up. A bit longer answer: it’s easier than you think.


Patching delayed_job for Ruby 3

Monkey patching is bad. That’s where you should start from. It can cause trouble where you’d least expect it, conflicts with libraries you’d least expect in ways you’d least expect. And yet here I am sharing code for patching the delayed_job gem to (more or less) work with Ruby 3. Doesn’t this violate my own policies? There are a few choices.

  1. give up upgrading to Ruby 3 altogether
  2. monkey patch delayed_job as an emergency fix and make time to figure out what to do
  3. contribute to delayed_job making sure the gem is solid on Ruby 3
  4. get rid of all the .delay calls and switch to another async job library