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+---
+title: "Declaratively Deploying Multiple Blog Versions with NixOS and Flakes"
+date: 2021-10-23T18:01:31-07:00
+expirydate: 2021-10-23T18:01:31-07:00
+draft: true
+tags: ["Hugo", "Nix"]
+---
+
+### Prologue
+
+You can skip this section if you'd like.
+
+For the last few days, I've been stuck inside of my room due to some kind of cold or flu, which
+or
+{{< sidenote "right" "pcr-note" "may or may not be COVID™." >}}
+The results of the PCR test are pending at the time of writing.
+{{< /sidenote >}}
+In seeming correspondence with the progression of my cold, a thought occured in the back of my mind:
+"_Your blog deployment is kind of a mess_". On the first day, when I felt only a small tingling in
+my throat, I waved that thought away pretty easily. On the second day, feeling unwell and staying
+in bed, I couldn't help but start to look up Nix documentation. And finally, on the third day,
+between coughing fits and overconsumption of oral analgesic, I got to work.
+
+In short, this post is the closest thing I've written to a fever dream.
+
+### The Constraints
+
+I run several versions of this site. The first is, of course, the "production" version, hosted
+at the time of writing on `danilafe.com` and containing the articles that I would like to share
+with the world. The second is a version of this site on which drafts are displayed - this
+way, I can share posts with my friends before they are published, get feedback, and even just
+re-read what I wrote from any device that has an internet connection. The third is the Russian
+version of my blog. It's rather empty, because translation is hard work, so it only exists
+so far as another "draft" website.
+
+My build process (a derivative of what I describe in [rendering mathematics on the back end]({{< relref "./backend_math_rendering.md" >}})) is also fairly unconventional. When I developed this site, the best
+form of server-side mathematics rendering was handlded by KaTeX, and required some additional
+work to get rolling (specifically, I needed to write code to replace sections of LaTeX on
+a page with their HTML and MathML versions). There may be a better way now, but I haven't yet
+performed any kind of migration. 
+
+Currently, only my main site is behind HTTPS. However, I would like for it to be possible to
+adjust this, and possibly even switch my hosts without changing any of the code that actually
+builds my blog.
+
+### Why Flakes
+This article is about using Nix Flakes to manage my configuration. But what is it that made
+me use flakes? Well, two things:
+
+* __Adding custom packages__. The Nix code for my blog provides a package / derivation for each
+  version of my website, and I want to use these packages in my `configuration.nix` so that
+  I can point various Nginx virtual hosts to each of them. This is typically done using
+  overlays, but I need a clean way to let my system configuration pull in my blog overlay (or blog
+  packages); flakes solve this issue my letting me specify a blog flake, and pull it in as one
+  of the inputs.
+* __Versioning__. My process for deploying new versions of the site prior to flakes boiled down to fetcing
+  the latest commit from the `master` branch of my blog repository, and updating the `default.nix`
+  file with that commit. This way, I could reliably fetch the version of my site that
+  I want published. Flakes do the same thing: the `flake.lock` file
+  contains the hashes of the Git-based dependencies of a flake, and thus prevents builds from
+  accidentally pulling in something else. However, unlike my approach, which relies on custom
+  scripts and extra tools such as `jq`, the locking mechanism used by flakes is provided with
+  standard Nix tooling. Using Flakes also guarantees that my build process won't break with
+  updates to Hugo or Ruby, since the `nixpkgs` version is stored in `flake.lock`, too.
+
+### The Final Result
+Here's the relevant section of my configuration:
+
+{{< codelines "Nix" "server-config/configuration.nix" 42 59 >}}
+
+I really like how this turned out for three reasons. First,
+it's very clear from the configuration what I want from my server:
+three virtual hosts, one with HTTPS, one with drafts, and one with drafts and
+_in Russian_. Second, there's plenty of code reuse. I'm using two builder functions,
+`english` and `russian`, but under the hood, the exact same code is being
+used to run Hugo and all the necessay post-processing. Finally, all of this can be
+used pretty much immediately given my blog flake, which reduces the amount of glue
+code I have to write.