Chameth.com - posts like docker-automatic-nginx-proxy, moving-back-to-a-dynamic-website, why-you-should-be-using-https but not how-i-get-things-done

Monthly Meanderings: April 2026

2026-05-01T00:00:00Z

It’s apparently been a whole month since the last edition of Monthly Meanderings. Not sure when that happened. This month I’ve been to a LAN party, had an MRI, and have been trying unsuccessfully to get my doctor to change a prescription. The latter two are not doing much to help shake that middle-aged feeling I mentioned last month…

Website updates

Another pair of blog posts for this month: The Case of the Unchanging Config about a problem I had with a bind-mounted config in a Docker container, and Migrating from GitHub to Forgejo, a write-up of… well… migrating from GitHub to Forgejo. That one’s been on my to-do list for a while, so it’s nice to finally get it written up.

It’s not visible when you look at the site, but I’ve been doing a lot of refactoring this month. The existing design had a package for database operations, a package for the stylesheet, a package for shortcodes, and so on. As I bolt more and more things on this gets less and less useful: those packages get bigger and bigger, and trying to understand how, say, the music import functionality works means hopping all over the place. Instead, I’m moving towards having each feature contained in its own package. It defines its own stylesheet, database operations, HTTP handlers, and so on. They’re then all wired together at the top layer. There’s still some more to do on that front, but it’s progressing in a good direction, and I’m happier with the code.

The only actual visible change is the addition of a page dedicated to World of Warcraft that automatically imports some data from the game’s API. We’ll come back to that later!

Other projects

I made a trio of new tiny projects: pdsps, a reverse proxy for a Bluesky/ATProto PDS that overrides the age verification response so you don’t need to hand over ID; irc-adze, a plugin for irc-bot that receives and announces adze webhooks; and wow-spec-switch, a super-simple addon for World of Warcraft that lets you switch specialisation with a command.

I’ve also been working on a custom app launcher in the style of ulauncher but without requiring WebKit to render things. I’ve not yet polished it up enough to open source it, but it’s not far off.

Entertainment

Another single film month for me. It was a great one, though:

Project Hail Mary

2026-04-01

A film adaptation of a book I loved that’s actually good. Huh!

Ryan Gosling does great in what is often a solo act. Early on I thought the film was trying a bit too hard to be funny, but at some point it started working and I enjoyed it.

There are lots of parallels to The Martian, Arrival, and so on, but it’s a sufficiently different mash-up of the concepts that it’s not a problem.

I’m still enjoying SNL UK a lot more than I expected to, although I keep forgetting what day it airs. They should put it in the name or something.

The rest of my “entertainment” time has been spent playing World of Warcraft. I played an awful lot about 6-7 years ago, and have dipped in and out occasionally since. I got an MMORPG itch again recently and jumped back in, and I’m enjoying it a lot once again. I’ve been playing a healer properly for the first time (after enjoying healing in Final Fantasy XIV):

Level 90

Female Void Elf

Holy Priest

280 average item level

Methrica-Terenas

Professions

Midnight Alchemy		100/100
Midnight Engineering		92/100
Midnight Cooking		1/100
Midnight Fishing		4/300

View on blizzard.com View on raider.io

Around the web

git-history documentation

The latest release of git added this handy-seeming history subcommand. It allows you to reword a commit, or split a commit up interactively, without having to go through the interactive rebase song and dance.

Git has acquired a bunch of new commands in recent releases, but I tend to ignore them in favour of the old ones I know well. This one will definitely get use from me, though.

Git Koans by Steve Losh

Sticking with the same theme, this series of koans about Git and its various quirks had me laughing. If you’re reading this blog, you’re probably part of the target audience for it.

SQLite prefixes its temp files with etilqs_

I think I’d come across this before, but it’s still a fun anecdote. It reminds me of Daniel Stenberg’s e-mail collection; as the author of curl his name is listed on basically everything with the inevitable influx of people contacting him.

A dot a day keeps the clutter away

I love this approach to tracking how frequently things are used, and the weird sort of archaeological record you get from rotating the colours of the stickers used.

Monthly Meanderings: February 2026

2026-03-01T00:00:00Z

It doesn’t feel like a whole month has gone past since I wrote the last instalment of Monthly Meanderings, even allowing for how short a month February is. For more context on this series, you can check out the introduction to the first edition.

Website updates

I only wrote one new blog post this month: Just a nod, which is about the “nod” button I added to the bottom of most pages. I did a lot of other little bits and pieces, though:

My blog posts are now automatically posted to a dedicated Bluesky account, and posts now include syndication links at the bottom.
The site now tracks how long each request takes to generate along with how many SQL queries were used. You can see the details for the current request by hovering/tapping over the pi symbol at the bottom right of a page. To understand why it’s a pi symbol, you should watch The Net!
Speaking of films, I redid the star rating rendering so instead of unicode stars it uses some hand-drawn pixel art stickers. They’re somewhat randomised, so they don’t look repetitive. This is what it now looks like: .
I spent some time tweaking various styles and layouts so everything works nicely on smaller screens. I try to make sure these things work when I make them, but it’s easy to miss a particular interaction, or make an innocent-seeming change that breaks tiny screens.
I added a new page that shows stats about my walks, based on my Apple Health data. I had a private view of this for a while, but decided there’s no reason it couldn’t be more public.
The films page has gained a search box, to directly find my review of a particular film. I used CSS anchor positioning for the results panel. Modern CSS is fun!
I fixed the 3D prints page being utterly broken in numerous ways. It showed up on my shiny new “how many SQL queries does each page do?” dashboard, as it was doing multiple queries for each individual print instead of just getting all the data in one go. Then I noticed a badly written redirect rule had broken all the images and download links. Whoops!
I did a lot of under-the-hood cleaning, most of which won’t be visible. Besides just making me happy, this means the contact form and nod buttons now work with Javascript disabled.
Finally, I added a page that shows my board game plays. The data comes from exports from bgstats. I have a bunch of ideas for other things to do with that data, but haven’t got around to it yet.

Phew. After writing all that out it feels like a really long month, not a short one!

Other projects

Not much going on with my other projects. The only big thing was goplum, my self-hosted monitoring/alerting tool, getting a 1.0 release. It adds a reminder feature so you can get alerted repeatedly if a service is down. It also reworks how plugins work so they’re compile-time instead of trying to be clever and dynamic, as that never really gave any benefits.

I’m still continuing my migration of projects to a private Forgejo instance. All of my personal repos are now sourced there, and mirrored out to GitHub, except one: my Dockerfiles. I’m not sure how I want to approach that yet, as the action that does the updating is pretty involved. I also have some repositories split off into their own GitHub organisations which I haven’t got around to mirroring yet.

Entertainment

Unlike the past few months, I didn’t touch many video games in February. The ones I’d been dabbling with didn’t really hook me enough to make me keep going back. I made up for it with lots of other media forms though. First up, a whole bunch of films:

I won’t write too much about them here — you can click through to read my reviews if you want — other than to call out the three excellent horror films I hadn’t seen before: Black Swan, The Cabin in the Woods, and Get Out. Not so long ago I would’ve said that I didn’t enjoy horror films, now they’re some my favourites.

I don’t have any TV show tracking on my website (yet?), as I haven’t really watched much recently. This month I started watching The Pitt though, and it rapidly become one of my favourite shows. By “started watching” I mean “watched every aired episode of both season 1 and season 2”. I highly recommend it. The only problem is that it’s hard to find anything to watch afterwards, as nothing else can quite measure up.

I’ve also been binging a book series: Beneath the Dragoneye Moons. It’s a LitRPG series: basically a fantasy setting that borrows systems from an RPG, like classes and levelling. Something about the genre really works for me, and Beneath the Dragoneye Moons is one of the more interesting series I’ve come across in the genre. I’ve been going through the series at the rate of about a book a day.

Finally, board games! Nothing particularly notable, but now I can embed a pretty display of what I actually played:

6 plays
4 plays
4 plays
4 plays
2 plays
2 plays
2 plays
2 plays
2 plays
2 plays
1 play
1 play
1 play
1 play
1 play
1 play
1 play
1 play
1 play
1 play
1 play

All of these were online via Board Game Arena. I haven’t really had time for in-person games with all the TV, films and reading!

Around the web

Start all of your commands with a comma

An old post that was doing the rounds again on Hacker News. It’s an interesting idea. I recently aliased cc to launch Claude Code with some custom parameters, and it horribly backfired when I tried to compile a C program and remembered that cc was part of GCC. I haven’t transitioned all my personal commands to use a prefix yet, but I might.

Tactical tornado is the new default

An interesting post about software developers who act as “tactical tornadoes”, and how that’s basically the role that all LLMs fill. Whenever I use coding agents, I often find myself following behind them in my IDE cleaning up bits and pieces. It’s often faster than prompting them to do it. I definitely get the “cleaning up after a tornado” metaphor.

Amusingly, the agents will sometimes notice that you’re tidying up after them and ascribe it to an automated process, outputting something like “the automated linter hasn’t run yet” if you fall behind. There’s probably a deeper philosophical discussion about what it means when the agent thinks that the human is the automated part of the system…

My smart sleep mask broadcasts users’ brainwaves to an open MQTT broker

Another one for the “the ’s’ in ‘IoT’ stands for security” books. I find it hard to actually comprehend how these things get to market. Does nobody actually think about it, or do they know full well how bad it is and just launch it anyway?

The IndieWeb and Small web

Ask three people to define ‘IndieWeb’ and ‘Small web’ and you’ll get about 20 different answers. This post by Christiano almost exactly nails my own views on the terms, and explains them well. I think most personal sites (my own included) straddle both terms to some extent, but having the labels is useful in discussions.

An interesting Tailscale + Docker gotcha

2026-01-29T00:00:00Z

As I’ve written about before, I use Tailscale for a lot of things. I thought I had it set up in a reasonably secure manner, but I recently noticed a problem.

I use Tailscale’s ACLs to limit what each node can access, based on the tags I apply to it. So an app node can’t access anything via Tailscale, while an integration or server node can access things tagged with either app or integration. This is expressed pretty simply in the Tailscale ACL JSON:

{
	"tagOwners": {
		// Servers that can be SSH'd into
		"tag:server": [],
		// Applications that are exposed on tailscale but never connect out
		"tag:app": [],
		// Things which talk to other services over tailscale (connecting to apps etc)
		"tag:integration": [],
	},
	"grants": [
		{
			// Users can access everything
			"src": ["autogroup:member"],
			"dst": ["*"],
			"ip":  ["*"],
		},
		{
			// Servers and integrations can access integrations and apps
			"src": ["tag:server", "tag:integration"],
			"dst": ["tag:integration", "tag:app"],
			"ip":  ["*"],
		},
	],
}

Over the past week I’ve been setting up a private Forgejo instance behind Tailscale, complete with an actions runner that runs things using a docker-in-docker container. I didn’t want the runner knowing anything about Tailscale, so I had it configured to speak to Forgejo direct over HTTP (forgejo:3000) instead of using full Tailscale HTTPS URL that I use when accessing it (http://git.example-net.ts.net/)¹.

Everything was going fine, until I forgot to do that translation… and it worked. My Forgejo action runners could access anything on my tailnet. I run several things on Tailscale that just have authentication turned off, on the basis that only authorised devices can access them. Things like the admin interface for this website. I definitely didn’t intend for any workflow I run on my git server to have access to edit my website!

This wasn’t just limited to Forgejo, either. Any docker container I was running could access the tailnet. In hindsight it’s fairly obvious why: the host is running Tailscale, connected as a node tagged with my server tag. That creates a tailscale0 interface, and automagically sets up iptables rules to route Tailscale traffic over the interface. Docker also automagically sets up iptables rules to bridge traffic, and apparently these two sets of rules interact in such a way that traffic from Docker containers is allowed to route via the tailscale0 interface.

I say it’s fairly obvious in hindsight — there’s no reason why Docker would special case any particular host interface after all — but it still feels pretty surprising. Because both bits of software inject their own iptables rules, I never really had a good mental model for how they interact. The host Tailscale node was a completely separate building block to Docker. It would be a pain to use either of them if they didn’t do these rules, but it’s also one of the reasons I don’t really like “magical” things².

There are lots of ways to fix this, but none of them feel particularly great. You can configure both Tailscale and Docker to not automatically fiddle with iptables and handle the rules yourself, but I really hate dealing with iptables³. As a stopgap I did hold my nose and add some iptables rules to drop traffic to the tailscale0 interface if it originated from the IP ranges that Docker was configured to use:

iptables -I DOCKER-USER -s 192.168.0.0/16 -o tailscale0 -j DROP
iptables -I DOCKER-USER -s 172.17.0.0/12 -o tailscale0 -j DROP

The DOCKER-USER chain is a nice little escape hatch; it comes before the main auto-generated DOCKER chain, and Docker leaves the rules in it alone.

So I added these rules, and felt pretty good about myself, and then… everything started breaking in weird ways. After some debugging I realised the problem was DNS⁴. The server’s DNS resolver is 100.100.100.100, a special Tailscale address. This is so that it can resolve tailnet hostnames via MagicDNS (and so I don’t have to configure my custom DNS servers manually on each device; Tailscale does it for me). My new iptables rules inadvertently dropped all the DNS packets coming from docker containers. D’oh.

Obviously the solution here is to double down and add MORE iptables rules:

iptables -I DOCKER-USER -s 192.168.0.0/16 -d 100.100.100.100 -o tailscale0 -j ACCEPT
iptables -I DOCKER-USER -s 172.17.0.0/12 -d 100.100.100.100 -o tailscale0 -j ACCEPT

This got DNS working again, but it all feels a bit gross. Not least because to actually make these persist you need to use iptables-save, and then you also get all the rules that both Docker and Tailscale have inserted. I came across a script to filter out the Docker ones, but… yuck⁵.

I realised a cleaner idea might just be to lock down what server tagged nodes could access within Tailscale itself. That way I can avoid touching iptables at all. It’s handy to be able to curl services from the host when debugging, but it’s not really necessary. So I removed that access, and… stuff broke again. I’m using my Forgejo instance as a registry for some of the docker images I run, so the docker daemon needs to be able to reach it. I ended up making a new tag for infrastructure, which can be accessed from server devices. This does still allow all the docker containers to reach Forgejo, but I already have it set up with appropriate access controls and public/private repository splits. Forgejo is a service designed to run publicly, so this seems a reasonable trade-off for convenience. I used the tests feature of Tailscale’s ACL config to make sure I’d got the rules right:

{
	"tests": [
		{
			// Servers can only access infrastructure
			"src":   "tag:server",
			"proto": "tcp",
			"allow": [
				"tag:infrastructure:8080",
			],
			"deny": [
				"100.84.16.43:8080",
				"me@example.com:8080",
				"tag:server:8080",
				"tag:app:8080",
				"tag:integration:8080",
			],
		},
	],
}

The whole situation still feels a bit messy. If I ever get around to switching to nftables I might loop back and manually craft some rules for routing traffic, instead of leaving Tailscale and Docker to do their own thing.

I discovered later on that logging into the container registry at forgejo:3000 actually issued a redirect to https://git.example-net.ts.net/ so this was all basically for naught… ↩︎
I didn’t use Tailscale’s MagicDNS for a long time just because the word “magic” put me off. Only when I eventually got around to learning how it worked, and seeing that it wasn’t really that magical under the hood, did I change my mind. ↩︎
nftables seems far better in lots of ways, but I can’t really be bothered migrating. Maybe next time I reimage the server for whatever reason… ↩︎
It’s always DNS… ↩︎
Again, nftables would almost certainly help here. It actually has (gasp) configuration files. But again, I really didn’t want to spend the time migrating. ↩︎

Moving back to a dynamic website

2025-10-28T00:00:00Z

For the past few weeks I’ve been working on converting chameth.com from a static site into a dynamically generated site backed by a database. This is the exact opposite process to one I went through maybe a decade ago. So why the change, and what’s different?

I’d actually been toying with the idea of switching for a while. Every now and then I’d have a thought along the lines of “it would be nice if I could add X to my website… but how would that work with static site generation?”. Comments, private drafts, dynamic themes based on the date, and many more little bits and pieces. You can definitely do them with a static site generator, but it felt like going against the grain. The beauty of a static site is that it’s… well… static. Shoehorning in dynamic features takes away a lot of the benefits, or leads to having lots of weird seams where you join the static and dynamic pieces together.

A bunch of things have changed since I originally switched to a static site generator. In no particular order:

The advent of containers, and managing them with config like in docker-compose, means standing up and managing a database for the site is trivial.
I’ve learnt and really like Golang, which makes writing HTTP-based servers a breeze, and makes it easy to deploy the site as a single binary (in a container).
LLM agents are good enough that I can have it do all the boring CRUD work needed to actually make a dynamic site work (so many admin functions…).

The code is open source if you’re interested. I’ve made no effort to make it generally useful outside of this website, but it might serve as a useful reference if you want to do something similar. Now that’s done, I can safely procrastinate on all those dynamic features I had planned!

Docker reverse proxying, redux

2022-12-06T00:00:00Z

Six years ago, I described my system for configuring a reverse proxy for docker containers. It involved six containers including a key-value store and a webserver. Nothing in that system has persisted to this day. Don’t get me wrong – it worked – but there were a lot of rough edges and areas for improvement.

Microservices and their limitations

My goal was to follow the UNIX philosophy of “do one thing and do it well”. Unfortunately, that doesn’t really work when applied to network services that have to interact with one and other. UNIX tools are built upon a common file system and simple data passed over STDIN. Microservices don’t have that shared foundation. You could make one: companies that use microservices in anger often have a team that deals with the “developer experience” of creating and using microservices. But as a solo developer that’s not something I wanted to spend my time doing.

This became very apparent when trying to debug issues. In the UNIX world, if your series of commands piped together does something strange you can simply echo the data at various stages. Not so much when that data is flying around on a network, going into and out of things like etcd. Trying to figure out why a certificate hadn’t been acquired was a case of searching through logs from four containers, none of which had particularly good logging. There are many ways to get insight into what’s happening with microservices but, again, that’s not something I wanted to do myself.

Over time, and with experience in other projects, I came to realise that microservices only really make sense if you’re unable to deploy a monolith. For tech companies this naturally happens when different teams contribute to the same service: splitting it out into smaller services that are wholly owned by individual teams makes sense. For solo developers, that never happens. You can still gain the other benefits of microservices – such as code separation and having clearly defined APIs – by sticking to certain coding standards.

Proxy inconveniences

As well as being unhappy with the microservice nature of the solution, I wasn’t pleased with nginx. If you requested an unknown domain, nginx would use the first server block in its config to serve a response, instead of sending an “unrecognised name” alert as I wanted. It was a minor issue, but it irked me.

So from nginx I switched to haproxy. It has a strict-sni option when configuring TLS connections which makes it behave properly. It also performs a lot better for this type of workload than nginx. All was well for a while, but then I started getting alerts that requests were occasionally failing. I couldn’t reproduce the issue, but my nightly jobs to build and push containers managed to hit it nearly every night, causing them to fail.

After some investigation, I found that the haproxy developers had refactored the header parsing code, and neglected to properly reset flags when multiple requests were sent over the same connection. There was a patch, but it wasn’t released. No problem, I thought, I’ll just cherry-pick it onto the last release… Except that haproxy use Git in the most convoluted manner I’ve ever seen – they have one repository per release. This makes it harder to patch, but it also made me question whether I trusted them to ship stable software: there were no tests for the header parsing code (which is both fundamental and finicky, the perfect target for tests), the source code management was weird, and they didn’t seem in any rush to patch this bug.

Not long after that issue, Greg managed to encounter another bug where haproxy returned a 500 error whenever the upstream server replied with a particular, perfectly valid, header. The die was cast – it was time to move to something else.

Not Invented Here syndrome

Looking for a new solution, there were many more options than back in 2016. I’m still convinced, however, that anything exposed to the Internet should not have access to run docker containers. It’s the modern equivalent of running a CGI script as root. That single requirement eliminates most off-the-shelf solutions. What do you do when nothing quite meets your specific requirements? You make something yourself! My new solution has two components: Dotege and Centauri.

Dotege is a replacement for the microservices that monitored containers and obtained certificates. It’s fundamentally a templating engine - whenever the containers change, it evaluates a template and saves the result to disk. The template has access to details about the containers, their labels, ports, and so on. Dotege can also obtain certificates from Let’s Encrypt, and raise a signal against another process whenever the template or certificates change. I used this to generate the configuration and certificates used by haproxy for a while, and more recently changed the template so that it works for Centauri.

Centauri is my own reverse proxy. It’s configured using a simple text file and can also obtain certificates from an ACME provider. It doesn’t serve static content, has no knowledge about docker, and avoids the other bells and whistles that adorn most reverse proxies. It also has good test coverage to ensure that I don’t, say, accidentally break header parsing.

As a software engineer I enjoy writing software, but I also enjoy running simple, easy to understand software. That’s what I’ve achieved here: it’s very easy to identify where the problem is if anything goes wrong, both are small Go programs rather than vast sprawling C monstrosities, and their interaction is primarily through a file written to disk that can be inspected or edited as needed.