Use slog.LogValuer interface
log/slog is no longer new in Go. It was
introduced in 2023 with Go 1.21. But it is very nice for structural logging.
Here’s how to make that structural logging work better for you:
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HTTP client logging in Go
So much of what we develop these days ends up using HTTP. Usually when
developing an HTTP service it’s quite easy to add logging to aid debugging. But
when developing a client, especially one that uses a library which does the
actual HTTP calls, it can be harder to insert logging in all the right places.
Docker pull-through cache for NixOS
Docker Hub has announced new pull limits starting
2024-04-01 . An easy way to get
around that is to set up a pull-through cache. This can easily be done using
 CNCF
Distribution .
Here’s how I did that on NixOS:
VictoriaLogs on NixOS
Searching for VictoriaLogs on
 search.nixos.org gave me no results, so I ran
victorialogs from Docker. But at some point I did search for victorialogs on
nixpkgs and realized that the binary is built with victoriametrics.
Template nesting in (text|html)/template
Go includes a safe and somewhat performant templating library. But the best way
to structure code using html/template has
eluded me for a long time.
Grafana with VictoriaLogs plugin on NixOS
VictoriaLogs looks like an
interesting alternative to Grafana Loki. But it would be nice to still query it
via the Grafana Dashboard along with all the rest. It takes a couple of specific
steps to install the appropriate plugin, especially on NixOS.
rsync backups for NixOS
There are several nice options in NixOS for specifying scheduled backup jobs,
including borgbackup, borgmatic and restic. But I’ve often used rsync in the
past, and there is no such module for scheduled rsync jobs (or rsnapshot
either). So I wrote my own simple module.
NixOS Mailer
There has been a lot of talk in recent years how running your own email server
is too hard. But it’s quite healthy for the email ecosystem to not have everyone
use Gmail and Outlook. In my experience it isn’t too hard, just takes some work.
Caddy plugins on NixOS
Caddy is a very handy HTTP server with lots of built-in features. But every once
in a while you need something more. Fortunately Caddy has a plugin API. But
Caddy being written in Go, the plugins need to be added at compile-time. On
NixOS, there are no plugins added by default, and there are a couple of things
to note when adding them.
Generic "must" helper for Go
Go error handling can be a bit verbose. There are a lot of places where errors
are unlikely or where they are so critical that a panic is preferred. Because of
this there are lots of Must* -helpers in various packages. E.g.
 regexp.MustCompile .
Docker Multiarch Builds
Like many other developers, I have to work with computers with different
processor architectures. For me it’s amd64 (x86_64) on the laptop and arm64
(aarch64) on the server. For some it may be the other way around. Fortunately I
mostly write Go, which makes cross-compilation quite easy. Docker adds some
extra steps, but is very nice for deploying software.
Deploy Hugo to NixOS on Push to Gitea
There are several ways to automate blog publishing from git push. This one is
mine. Mostly notes for future self. I use Gitea ,
 Hugo , Caddy and
 NixOS .
WebAuthn & Base64 encoding
I recently ran into a problem that seems to be present in a wide range of
 WebAuthn tutorials, but I don’t know where
it originated.
SSH PKI on top of Web PKI
Reading Future Internet PKI schemes need to be bootstrapped through web
PKI I was
reminded by all the problems I’ve had with SSH (Secure SHell) PKI (Public Key
Infrastructure). SSH host verification is trust-on-first-use (TOFU). So SSH is
protected from man-in-the-middle (MITM) attacks unless the first connection
falls prey to the attack.
Molly Guard for Ansible
The Jargon File defines Molly
Guard as: 
 
 A shield to prevent tripping of some Big Red Switch by clumsy or ignorant
hands. Originally used of the plexiglass covers improvised for the BRS on an
IBM 4341 after a programmer’s toddler daughter (named Molly) frobbed it twice
in one day. Later generalized to covers over stop/reset switches on disk
drives and…
Menu-driven Matrix Bot Interaction
I’m a huge fan of Matrix . A lot of the user value of
modern chat platforms like Slack, Matrix and Discord (even IRC) comes from
integrations to other services via bots. I had high hopes for MSC3006: Bot
Interactions ,
but unfortunately it isn’t currently being pushed further. However, there exists
an implementation of MSC3381:
Polls .
Selectively running single role in Ansible
While I’ve been switching from Ansible to Nix lately, I still use Ansible and
have written a fair share of Ansible YAML. A common trick I’ve used is to only
run a specific Ansible role instead of the whole playbook. That can be achieved
by using tags, but usually I haven’t tagged everything before I have the need.
Shorter wrapped error handling in Go
With Go 1.13 error wrapping was
standardised with an interface in the standard library. When properly handling
errors, you end up dealing with it a lot. The blog post suggests the following: 
 var e * QueryError 
 if errors . As ( err , & e ) {
 	 // err is a *QueryError, and e is set to the error's value 
 }

Generic pointer of value with Go
I’ve been writing a decent amount of Go during the past 8 years. While I like many
things about Go, some of the design choices result in repetitive or longer
than necessary code.
GlitchTip on arm64
Why does everything have to be so hard on arm64? Well, maybe not directly hard,
but a lot more work. And the reason is simple, we live almost in a amd64
monoculture. Mobile phones are changing that, as is Apple M1, but also arm64
servers.
Roborock S6 Pure Troubleshooting
We have a Roborock S6 Pure robotic
vacuum cleaner . It’s very nice
having a device that more or less cleans the floors by itself. When it works.
Ours stopped working a week ago, after working well for months.
Matrix Bot for the reMarkable eInk Tablet
I own a reMarkable 2 (referral
link) eInk tablet. It’s pretty nice
(except lately the manufacturer has tacked on a subscription service). And it
can send documents as PDFs via email. But unlike the Kindle, you cannot send
documents to the tablet via email. Well, there exists a third party
service . 
 I saw someone post on
reddit 
that they wrote a Telegram bot…
coturn for Ubuntu Jammy (22.04 LTS)
Today I had to install coturn on Ubuntu
22.04 (Jammy Jellyfish). It doesn’t have
 package available because
of a bug . But
there’s a solution on the bugtracker, so I decided to build my own package. It
has been a while since I last did it, so here are the steps for reference:
Blog Comments with Matrix Using Cactus Comments
I’m not sure if comments improve blogs, but I’m willing to try. But my blog is a
static site and I don’t like the idea of forcing Disqus on readers of my blog. Luckily there exists a project
built on matrix for adding comments to your site.
Login Using Already Existing Matrix Account
I have a deep interest in both matrix and different
authentication schemes. When I saw the HN discussion about “Sign in with
Matrix” , I thought I could
probably come up with something better.
Guide for Free Matrix Home Server
Having been on the Internet for decades, I’ve seen the growth of walled gardens
and the associated problems. I hate it. Especially the messaging walled gardens.
RFC7807 - Problem Details for HTTP APIs
At some point when implementing HTTP APIs, just logging “error” and returning an
empty response doesn’t cut it anymore. Good practise with REST APIs suggests
returning a suitable HTTP status code, i.e. something other than 200 OK.
JWT Debugging
I need to remember to not stop at the following:
NixOS on Oracle Cloud
Oracle Cloud offers nice free virtual machines, but there was no installation
image for NixOS. Luckily NixOS-infect 
worked really great.
Free clouds
Comparison of free cloud offerings (2023/08):
Unprofessional Support in MacHuolto, start of a blog
First, some background. I have an iBook G4 12" that I bought in August 2005, so
that I would have a handy laptop during my studies. I also bought AppleCare,
because I thought it would be better to pay 300€ extra to be sure that the
laptop would serve me at least three years, instead of the one year default
warranty. Of that decision, I’m glad.