chore: big dump

2023-11-16 09:34:09 +01:00 · 2023-11-16 09:34:09 +01:00 · 9f7a77273f
parent 12173463ab
commit 9f7a77273f
22 changed files with 766 additions and 176 deletions
--- a/.gitea/workflows/build.yaml
+++ b/.gitea/workflows/build.yaml
@ -0,0 +1,19 @@
+name: Gitea Actions Demo
+run-name: ${{ gitea.actor }} is testing out Gitea Actions
+on: [push]
+
+jobs:
+  Explore-Gitea-Actions:
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo "The job was automatically triggered by a ${{ gitea.event_name }} event."
+      - run: echo "This job is now running on a ${{ runner.os }} server hosted by Gitea!"
+      - run: echo "The name of your branch is ${{ gitea.ref }} and your repository is ${{ gitea.repository }}."
+      - name: Check out repository code
+        uses: actions/checkout@v3
+      - run: echo "The ${{ gitea.repository }} repository has been cloned to the runner."
+      - run: echo "The workflow is now ready to test your code on the runner."
+      - name: List files in the repository
+        run: |
+          ls ${{ gitea.workspace }}
+      - run: echo "This job's status is ${{ job.status }}."
--- a/README.md
+++ b/README.md
@ -1,5 +1,3 @@
 # blog

 [![Build Status](https://ci.meatbag.se/api/badges/varl/blog/status.svg)](https://ci.meatbag.se/varl/blog)
-
-
--- a/lib/css/main.css
+++ b/lib/css/main.css
@ -7,7 +7,14 @@

@layer base {
  html {
-    font-family: IBM Plex Mono, ui-monospace, monospace;
+    font-family:
+      IBM Plex Mono,
+      ui-monospace,
+      monospace;
+  }
+
+  a {
+    @apply underline underline-offset-4 decoration-slate-500 hover:decoration-indigo-500;
  }
 }

--- a/lib/layouts/index.njk
+++ b/lib/layouts/index.njk
@ -9,10 +9,11 @@
 {% for date, posts in collections.posts | groupby('pub.year') | dictsort | reverse %}
    <h2 class="{{classes.h2}}">{{ date }}</h2>
    <hr class="{{ classes.hr }}"/>
+
    {% for post in posts %}
        <div>
            <h4 class="{{ classes.h4 }}"><a href="{{ post.permalink }}">{{ post.title | safe }}</a></h4>
-            <h5>{{ post.description | safe }}</h5>
+            <h5 class="{{ classes.post_date }}">{{post.date}}</h5>
        </div>
    {% else %}
        No posts
--- a/lib/layouts/post.njk
+++ b/lib/layouts/post.njk
@ -4,18 +4,21 @@

    {{ contents | safe }}

+    {% if previous or next %}
+        <hr class="{{ classes.hr }}"/>
+        <div class="flex flex-row justify-around">
            {% if previous %}
                <p>
-Previous:
-<a href="/{{ previous.path }}">{{ previous.title }}</a>
+                    Previous: <a href="/{{ previous.path }}">{{ previous.title }}</a>
                </p>
            {% endif %}

            {% if next %}
                <p>
-Next:
-<a href="/{{ next.path }}">{{ next.title }}</a>
+                    Next: <a href="/{{ next.path }}">{{ next.title }}</a>
                </p>
            {% endif %}
+        </div>
+    {% endif %}

 {% endblock %}
--- a/lib/tailwind-renderer.js
+++ b/lib/tailwind-renderer.js
@ -13,13 +13,15 @@ export const classes = {
  hr: 'border-red-900',
  code: 'text-slate-400',
  image: 'grayscale',
-}
+  post_date: 'text-base italic',
+};

 export const rules = (md) => {
-    const proxy = (tokens, idx, options, env, self) => self.renderToken(tokens, idx, options);
+  const proxy = (tokens, idx, options, env, self) =>
+    self.renderToken(tokens, idx, options);
  const defaultRenderer = (name) => md.renderer.rules[name] || proxy;

-    const defaultBulletListOpenRenderer = defaultRenderer('bullet_list_open')
+  const defaultBulletListOpenRenderer = defaultRenderer('bullet_list_open');
  const defaultBlockquoteOpenRenderer = defaultRenderer('blockquote_open');
  const defaultHeadingOpenRenderer = defaultRenderer('heading_open');
  const defaultCodeOpenRenderer = defaultRenderer('code_inline');
@ -27,42 +29,40 @@ export const rules = (md) => {
  const defaultImageRenderer = defaultRenderer('image');

  return {
-        footnote_block_open: () => (
+    footnote_block_open: () =>
      `<hr class="${classes.hr}">\n` +
      `<section class="${classes.footnote_section}">\n` +
-          `<ol class="${classes.footnote}">\n`
-        ),
+      `<ol class="${classes.footnote}">\n`,

    bullet_list_open: (tokens, idx, options, env, self) => {
-            tokens[idx].attrJoin("class", classes.bullet_list);
+      tokens[idx].attrJoin('class', classes.bullet_list);

      return defaultBulletListOpenRenderer(tokens, idx, options, env, self);
    },

    blockquote_open: (tokens, idx, options, env, self) => {
-            tokens[idx].attrJoin("class", classes.blockquote);
+      tokens[idx].attrJoin('class', classes.blockquote);
      return defaultBlockquoteOpenRenderer(tokens, idx, options, env, self);
    },

    heading_open: (tokens, idx, options, env, self) => {
-            tokens[idx].attrJoin("class", classes[tokens[idx].tag]);
+      tokens[idx].attrJoin('class', classes[tokens[idx].tag]);
      return defaultHeadingOpenRenderer(tokens, idx, options, env, self);
    },

    code_inline: (tokens, idx, options, env, self) => {
-            tokens[idx].attrJoin("class", classes.code);
+      tokens[idx].attrJoin('class', classes.code);
      return defaultCodeOpenRenderer(tokens, idx, options, env, self);
    },

    hr: (tokens, idx, options, env, self) => {
-            tokens[idx].attrJoin("class", classes.hr);
+      tokens[idx].attrJoin('class', classes.hr);
      return defaultHrRenderer(tokens, idx, options, env, self);
    },

    image: (tokens, idx, options, env, self) => {
-            tokens[idx].attrJoin("class", classes.image);
+      tokens[idx].attrJoin('class', classes.image);
      return defaultImageRenderer(tokens, idx, options, env, self);
    },
-    }
-}
-;
+  };
+};
--- a/metalsmith.js
+++ b/metalsmith.js
@ -23,7 +23,7 @@ import { rules, classes } from './lib/tailwind-renderer.js';
 const __dirname = dirname(fileURLToPath(import.meta.url));
 const t1 = performance.now();

-let md
+let md;

 Metalsmith(__dirname)
  .source('./src')
@ -41,10 +41,12 @@ Metalsmith(__dirname)
    generatorurl: 'https://metalsmith.io/',
    classes,
  })
-  .use(drafts({
+  .use(
+    drafts({
      default: false,
      include: false,
-  }))
+    }),
+  )
  .use(
    markdown({
      render: function (source, options, context) {
@ -58,9 +60,9 @@ Metalsmith(__dirname)
        }

        if (context.key == 'contents') {
-            return md.render(source)
+          return md.render(source);
        } else {
-            return md.renderInline(source)
+          return md.renderInline(source);
        }
      },
      engineOptions: {
@ -68,12 +70,17 @@ Metalsmith(__dirname)
        highlight: function (str, lang) {
          if (lang && hljs.getLanguage(lang)) {
            try {
-                      return `<pre class="${classes.hljs}"><code>${hljs.highlight(str, { language: lang, ignoreIllegals: true }).value}</code></pre>`;
+              return `<pre class="${classes.hljs}"><code>${
+                hljs.highlight(str, { language: lang, ignoreIllegals: true })
+                  .value
+              }</code></pre>`;
            } catch (__) {}
          }

-              return `<pre class="${classes.hljs}"><code>${md.utils.escapeHtml(str)}</code></pre>`;
-          }
+          return `<pre class="${classes.hljs}"><code>${md.utils.escapeHtml(
+            str,
+          )}</code></pre>`;
+        },
      },
    }),
  )
@ -83,7 +90,7 @@ Metalsmith(__dirname)
        pattern: 'posts/**/*.html',
        sortBy: 'date',
        reverse: false,
-      }
+      },
    }),
  )
  .use(
@ -95,15 +102,15 @@ Metalsmith(__dirname)
        remove: /[^a-z0-9- ]+/gi,
        lower: true,
        extend: {
-              "'": '-'
-          }
+          "'": '-',
+        },
      },
    }),
  )
  .use(
    inplace({
-        transform: 'nunjucks'
-      })
+      transform: 'nunjucks',
+    }),
  )
  .use(
    layouts({
--- a/package-lock.json
+++ b/package-lock.json
@ -12,6 +12,7 @@
        "@metalsmith/markdown": "1.10.0",
        "@metalsmith/permalinks": "2.5.1",
        "@metalsmith/postcss": "5.4.1",
+        "@metalsmith/rss": "1.0.1",
        "autoprefixer": "10.4.14",
        "highlight.js": "11.8.0",
        "jstransformer-nunjucks": "1.2.0",
@ -190,6 +191,14 @@
        "postcss": "^5.0.4 || ^6.0.0 || ^7.0.0 || ^8.0.0"
      }
    },
+    "node_modules/@metalsmith/rss": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/@metalsmith/rss/-/rss-1.0.1.tgz",
+      "integrity": "sha512-27untrvM6ltnFbeSajzSU5e+7zJ4EfUsyqWR8m64S9GXw1gQqKnZbDKMhPbmHv8AMXVqtGPCayhBcYjJWKj+hQ==",
+      "dependencies": {
+        "rss": "^1.2.2"
+      }
+    },
    "node_modules/@nodelib/fs.scandir": {
      "version": "2.1.5",
      "resolved": "https://registry.npmjs.org/@nodelib/fs.scandir/-/fs.scandir-2.1.5.tgz",
@ -897,6 +906,25 @@
        "node": ">=8.6"
      }
    },
+    "node_modules/mime-db": {
+      "version": "1.25.0",
+      "resolved": "https://registry.npmjs.org/mime-db/-/mime-db-1.25.0.tgz",
+      "integrity": "sha512-5k547tI4Cy+Lddr/hdjNbBEWBwSl8EBc5aSdKvedav8DReADgWJzcYiktaRIw3GtGC1jjwldXtTzvqJZmtvC7w==",
+      "engines": {
+        "node": ">= 0.6"
+      }
+    },
+    "node_modules/mime-types": {
+      "version": "2.1.13",
+      "resolved": "https://registry.npmjs.org/mime-types/-/mime-types-2.1.13.tgz",
+      "integrity": "sha512-ryBDp1Z/6X90UvjUK3RksH0IBPM137T7cmg4OgD5wQBojlAiUwuok0QeELkim/72EtcYuNlmbkrcGuxj3Kl0YQ==",
+      "dependencies": {
+        "mime-db": "~1.25.0"
+      },
+      "engines": {
+        "node": ">= 0.6"
+      }
+    },
    "node_modules/minimatch": {
      "version": "3.1.2",
      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.1.2.tgz",
@ -1300,6 +1328,15 @@
        "node": ">=0.10.0"
      }
    },
+    "node_modules/rss": {
+      "version": "1.2.2",
+      "resolved": "https://registry.npmjs.org/rss/-/rss-1.2.2.tgz",
+      "integrity": "sha512-xUhRTgslHeCBeHAqaWSbOYTydN2f0tAzNXvzh3stjz7QDhQMzdgHf3pfgNIngeytQflrFPfy6axHilTETr6gDg==",
+      "dependencies": {
+        "mime-types": "2.1.13",
+        "xml": "1.0.1"
+      }
+    },
    "node_modules/run-parallel": {
      "version": "1.2.0",
      "resolved": "https://registry.npmjs.org/run-parallel/-/run-parallel-1.2.0.tgz",
@ -1553,6 +1590,11 @@
      "resolved": "https://registry.npmjs.org/wrappy/-/wrappy-1.0.2.tgz",
      "integrity": "sha512-l4Sp/DRseor9wL6EvV2+TuQn63dMkPjZ/sp9XkghTEbV9KlPS1xUsZ3u7/IQO4wxtcFB4bgpQPRcR3QCvezPcQ=="
    },
+    "node_modules/xml": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/xml/-/xml-1.0.1.tgz",
+      "integrity": "sha512-huCv9IH9Tcf95zuYCsQraZtWnJvBtLVE0QHMOs8bWyZAFZNDcYjsPq1nEx8jKA9y+Beo9v+7OBPRisQTjinQMw=="
+    },
    "node_modules/yaml": {
      "version": "2.3.1",
      "resolved": "https://registry.npmjs.org/yaml/-/yaml-2.3.1.tgz",
--- a/src/index.md
+++ b/src/index.md
@ -2,5 +2,3 @@
 title: index
 layout: index.njk
 ---
-
-asdf
--- a/src/posts/2019/bash-powered-flat-file-blog.md
+++ b/src/posts/2019/bash-powered-flat-file-blog.md
@ -4,6 +4,7 @@ date: 2019-08-01
 pub:
  year: 2019
 ---
+
 # Bash powered flat-file blog

 I've been meaning to put something on this space for a long time, yet I
@ -32,7 +33,7 @@ extensions to it.
 It is Java however and since I've reduced the specs for this virtual
 server (cost optimization) and tried to outsource some of the tasks it
 previously did, so Java had to go. It was also a chore updating and
-recompiling the thing. *cough* Made up excuses. *cough*
+recompiling the thing. _cough_ Made up excuses. _cough_

 It was hard enough to find a Wiki software that used Git as a backing
 storage system. Eventually I settled on [Gitit]() that gives me the
--- a/src/posts/2019/chili.md
+++ b/src/posts/2019/chili.md
@ -178,4 +178,3 @@ FOTNOT 4: denna text får fritt spridas och kopieras under förutsättning att n
 inte blandar bönor i chilin.

 ---
-
--- a/src/posts/2020/house.md
+++ b/src/posts/2020/house.md
@ -4,6 +4,7 @@ date: 2020-06-01
 pub:
  year: 2020
 ---
+
 # 2020 so far

 This has been a stranger year than most, even when not taking COVID-19
--- a/src/posts/2020/key-to-success.md
+++ b/src/posts/2020/key-to-success.md
@ -4,6 +4,7 @@ date: 2020-06-01
 pub:
  year: 2020
 ---
+
 # The Key to success

 Wisdom from my grandparents:
--- a/src/posts/2020/monitor-with-irc.md
+++ b/src/posts/2020/monitor-with-irc.md
@ -4,6 +4,7 @@ date: 2020-09-01
 pub:
  year: 2020
 ---
+
 # Monitoring with IRC

 I would like to keep an eye on my servers from the comfort of my IRC
--- a/src/posts/2023/varls-nixtape-vol-1.md
+++ b/src/posts/2023/varls-nixtape-vol-1.md
@ -40,7 +40,8 @@ language", and not "nix the operating system"), is quite mature[^1]
 across both Linux and MacOS, so I decided to brush off my "nix the
 language" concerns and dive into it. Again.

-[^1]: Well, `nix-env` and other `nix-*` commands _are_ mature, but the
+[^1]:
+    Well, `nix-env` and other `nix-*` commands _are_ mature, but the
    next-gen all-in-one `nix` CLI is definitely _not_ mature. It's not
    even final:
    https://nixos.org/manual/nix/stable/command-ref/experimental-commands
@ -54,10 +55,12 @@ language" concerns and dive into it. Again.
 - Comfortable using a shell
 - A high tolerance for obtuse languages[^3]

-[^2]: Configuration guide:
+[^2]:
+    Configuration guide:
    https://devblogs.microsoft.com/commandline/systemd-support-is-now-available-in-wsl/

-[^3]: We will be using a bare minimum of "nix the language" to
+[^3]:
+    We will be using a bare minimum of "nix the language" to
    accomplish our goals, so there are better ways to do most things I
    do, but I don't understand any of them so I'm sticking to what I can
    only describe as "simple but dumb".
@ -73,7 +76,8 @@ Nix is somewhat of an overloaded term, as it can mean:
 - Nix the utilities
 - Nix the store

-[^4]: Most often called NixOS but searching for "nix" often winds up in
+[^4]:
+    Most often called NixOS but searching for "nix" often winds up in
    NixOS-land which is not always helpful.

 I will use a subset of those in this guide, and do my best to
@ -132,7 +136,8 @@ advanced functionality (often experimental) that the official installer
 leaves off by default, and goes as far as to disable or dissuade users
 from using the stable nix utilities.

-[^5]: A consultancy that provides services related to Nix training for
+[^5]:
+    A consultancy that provides services related to Nix training for
    teams and companies.

 It's a great installer, but if used, some configuration options must be
@ -245,7 +250,8 @@ versions of the same package can exist at the same time (at the cost of
 disk space) without causing conflicts across the environment. There is
 also a long version[^6]. Probably a longer version somewhere as well.

-[^6]: Understanding the Nix store by looking at how Nix works:
+[^6]:
+    Understanding the Nix store by looking at how Nix works:
    https://nixos.org/guides/how-nix-works.html

 ### Installing packages into the environment
--- a/src/posts/2023/varls-nixtape-vol-3.md
+++ b/src/posts/2023/varls-nixtape-vol-3.md
@ -1,15 +1,521 @@
 ---
 title: varl's nixtapes vol.3
-date: 2023-08-15
+date: 2023-08-29
 pub:
  year: 2023
 collection: nixtapes
 ---

-# Context
+> #### TL;DR
+>
+> Let us cut into the meat of Nix and finally take a look at how we can
+> use what we tediously went through [vol.1](../varls-nixtape-vol-1) and
+> [vol.2](../varls-nixtape-vol-2) for. Declarative and isolated
+> development environments.

-# Prerequisites
+# volume 3: declarative developer environments

- Declarative development environments
- Nested nix environments.
- Setting up WARP and `app` command
+## Prerequisites
+
+- Again we need a working nix installation, see
+  [vol.1](../varls-nixtape-vol-1)
+- We also need Nix integrated with the user environment, see
+  [vol.2](../varls-nixtape-vol-2)
+
+## Context
+
+Why do we want declarative development environments ?
+
+To be fair, once an development environment has been set up, it mostly
+chugs along just fine, and will do so for some time.
+
+Eventually the developer needs to update something, for example NodeJS
+to another version. She can choose to do so globally, forcing all the
+apps she works on to run on the global version provided. That might not
+be ideal, so there are tools that solve this problem by allowing her to
+install multiple versions of Node and either set one for a specific
+project, or manually switch between them.
+
+There are many, many, tools that do this (to list a few):
+
+- Polyglot: [asdf](https://asdf-vm.com/)
+- NodeJS: [volta](https://github.com/volta-cli/volta),
+  [fnm](https://github.com/Schniz/fnm), [n](https://github.com/tj/n),
+  [nvm](https://github.com/nvm-sh/nvm)
+- Python: [pyenv](https://github.com/pyenv/pyenv),
+  [venv](https://docs.python.org/3/library/venv.html)
+- Rust: [r](https://github.com/javanile/r),
+  [rustup](https://rustup.rs/),
+  [zrsvm](https://github.com/zcorky/zrsvm),
+  [rsvm](https://github.com/sdepold/rsvm)
+- Go: [gvm](https://github.com/moovweb/gvm),
+  [g](https://github.com/stefanmaric/g)
+
+Nix however, can replace all of these. It circumvents the problem by
+changing the paradigm. What if all versions can be installed
+side-by-side, making it so that there is no truly global version at all
+?
+
+There may be a _default_ version, sure, but with declarative
+environments we can switch between them automatically, or at will. And
+once we leave the environment where we loaded the tool, it is removed,
+so it only exists in the context we want it in.
+
+By using a declarative style, we tell the system what state we want it
+to be in, and the system moves to that state. And we can do that at any
+granularity: coarse (all of our development), or fine (just a single
+project).
+
+On with the show.
+
+## Our first development environment
+
+Having an organised folder structure will have an immense impact on how
+reusable how environments will be, and allow for tricks like nesting
+developer environments. I expect most developers have a folder that
+contains the projects that they work on, and for now that is perfectly
+fine.
+
+If you don't have something like that though, and dump all projects in
+your `$HOME` ... May I suggest to create a `~/dev` folder, at least for
+the purpose of this experiment.
+
+Jump into `~/dev` and create a new file called `shell.nix`. This is
+where we will declare what our environment should be:
+
+Starting with some basics, let's add NodeJS 18, Python 3, Go 1.20, and
+Java 17.
+
+```
+with (import <nixpkgs> {});
+
+mkShell {
+  buildInputs = [
+    nodejs-18_x
+    python3
+    python3.pkgs.pip
+    go_1_20
+    maven
+    jdk17
+  ];
+
+  shellHook = ''
+  '';
+}
+```
+
+Save and exit the file, and type `nix-shell`. After a bit of
+downloading and plumbing, you will be dropped into a shell environment
+that may change your prompt:
+
+```
+~/dev% nix-shell
+
+[nix-shell:~/dev]$
+```
+
+In the shell we can see that we indeed have an environment with the
+tools we declared[^1]:
+
+```
+[nix-shell:~/dev]$ node --version
+v18.17.1
+
+[nix-shell:~/dev]$ go version
+go version go1.20.7 linux/amd64
+
+[nix-shell:~/dev]$ javac -version
+javac 17.0.7
+
+[nix-shell:~/dev]$ python3 --version
+Python 3.10.12
+```
+
+[^1]:
+    We just started `nix-shell` in an impure state, meaning it merges
+    our existing environment with the created shell. If we had provided
+    the `--pure` switch, then no system tools would be visible within
+    the Nix shell. See [vol.1](../varls-nixtape-vol-1) for more on this.
+
+We can also make sure we are in fact using the versions provided by Nix:
+
+```
+[nix-shell:~/dev]$ which python3
+/nix/store/wlxpsdzfvdanfzh704qmgyzb42qvy4fr-python3-3.10.12/bin/python3
+
+[nix-shell:~/dev]$ which node
+/nix/store/5my366b5ws4mnmycnynrwiwmz93zj37b-nodejs-18.17.1/bin/node
+
+[nix-shell:~/dev]$ which go
+/nix/store/54qksp8q7lwwhpjyxqbhzvrmn883gkpy-go-1.20.7/bin/go
+
+[nix-shell:~/dev]$ which javac
+/nix/store/l4plrvlxi46fiy65sz75x7850wx0nhhw-openjdk-17.0.7+7/bin/javac
+```
+
+Exit the `nix-shell` environment, and poof. The tools are either gone or
+reverted to whatever I had before:
+
+```
+~/dev% which javac
+javac not found
+```
+
+That's a neat trick, but we don't want to type `nix-shell`, and we
+absolutely don't want to change our prompt and/or drop into bash when we
+are using zsh in our main environment. We _want_ some things to blend
+between environments.
+
+## Enter: `direnv` and `nix-direnv`
+
+> - https://github.com/direnv/direnv
+> - https://github.com/nix-community/nix-direnv
+
+These two tools will do the heavy lifting for us. `direnv` should be
+installed in our user environment that we set up in [vol.2](../varls-nixtape-vol-2).
+
+So jumping back to `~/.config/nixpkgs/config.nix`, we can add it to our
+`userBasePkgs`:
+
+```diff
+pkgs : {
+    allowUnfree = true;
+    packageOverrides = pkgs: with pkgs; rec {
+        nixUserProfile = writeText "nix-user-profile" ''
+            export PATH=$HOME/.nix-profile/bin:/nix/var/nix/profiles/default/bin:/sbin:/bin:/usr/sbin:/usr/bin
+            export NIX_PATH="nixpkgs=$HOME/.nix-defexpr"
+        '';
+        userBasePkgs = pkgs.buildEnv {
+            name = "user-base";
+            paths = [
+                (runCommand "profile" {} ''
+                    mkdir -p $out/etc/profile.d
+                    cp ${nixUserProfile} $out/etc/profile.d/nix-user-profile.sh
+                '')
+               direnv
+            ];
+            pathsToLink = [
+                "/share"
+                "/bin"
+                "/etc"
+            ];
+            extraOutputsToInstall = [ "man" "doc" ];
+        };
+    };
+}
+```
+
+And we instruct Nix to set up our user environment with `nix-env -ir user-base`.
+
+Now `direnv` should be available:
+
+```
+$ which direnv
+/nix/store/h77a0hqm3jcfqq7fgs310rf5l9w9g66y-direnv-2.32.3/bin/direnv
+```
+
+Last installation step for `direnv` is to hook it into our environment.
+In `.zshrc` or `.bashrc` add the line for your shell[^2]:
+
+```
+# for zsh
+eval "$(direnv hook zsh)"
+
+# for bash
+eval "$(direnv hook bash)"
+```
+
+[^2]: For more shell integrations: https://github.com/direnv/direnv/blob/master/docs/hook.md
+
+Now, create a `.envrc` in your `~/dev` folder, making it a sibling with
+`shell.nix`:
+
+```
+~/dev% tree -L 1
+.
+├── shell.nix
+└── .envrc
+```
+
+Add this content to `.envrc`:
+
+```
+use nix
+```
+
+Save and quit, and then run `direnv allow` in the `~/dev` folder to
+allow `direnv` to load the file automatically.
+
+It never runs any `.envrc` that isn't explicitly
+allowed, and if the `.envrc` file changes, you need to manually allow it
+again. This is a safeguard in case someone for example sneaks an `.envrc`
+file into version control.
+
+Upon running `direnv allow`, it will immediately source the `.envrc`
+file and load the environment as specified. It will spit out something
+like this:
+
+```
+~/dev% direnv allow
+
+direnv: loading ~/dev/.envrc
+direnv: using nix
+direnv: export +AR +AS +CC +CONFIG_SHELL +CXX +DETERMINISTIC_BUILD
+HOST_PATH +IN_NIX_SHELL +JAVA_HOME +LD +NIX_BINTOOLS
+NIX_BINTOOLS_WRAPPER_TARGET_HOST_x86_64_unknown_linux_gnu
+NIX_BUILD_CORES +NIX_BUILD_TOP +NIX_CC
+NIX_CC_WRAPPER_TARGET_HOST_x86_64_unknown_linux_gnu +NIX_CFLAGS_COMPILE
+NIX_ENFORCE_NO_NATIVE +NIX_HARDENING_ENABLE +NIX_LDFLAGS +NIX_STORE +NM
+NODE_PATH +OBJCOPY +OBJDUMP +PYTHONHASHSEED +PYTHONNOUSERSITE
+PYTHONPATH +RANLIB +READELF +SIZE +SOURCE_DATE_EPOCH +STRINGS +STRIP
+TEMP +TEMPDIR +TMP +TMPDIR +XDG_DATA_DIRS +_PYTHON_HOST_PLATFORM
+_PYTHON_SYSCONFIGDATA_NAME +__structuredAttrs +buildInputs +buildPhase
+builder +cmakeFlags +configureFlags +depsBuildBuild
+depsBuildBuildPropagated +depsBuildTarget +depsBuildTargetPropagated
+depsHostHost +depsHostHostPropagated +depsTargetTarget
+depsTargetTargetPropagated +doCheck +doInstallCheck +mesonFlags +name
+nativeBuildInputs +out +outputs +patches +phases +preferLocalBuild
+propagatedBuildInputs +propagatedNativeBuildInputs +shell +shellHook
+stdenv +strictDeps +system ~PATH
+
+~/dev%
+```
+
+If you have new packages, it can take some time for it to download them
+and put them in the `/nix` store. Hang tight. Subsequent loads will be
+faster, and through the power of caching, we can make them even faster.
+
+Any changes to `shell.nix` will be picked up and trigger `direnv` to
+load our changed environment.
+
+At this point we could call it a day, but it's a bit too slow, so let's
+add in an extension to `direnv` called `nix-direnv` that caches our
+development environments, making them a lot faster to load, after the
+cache is populated.
+
+There are a few ways to install `nix-direnv`, either by adding it to our
+user configuration[^3], or by using a directive in `.envrc` to load it
+for us (also cached, so not done each time):
+
+[^3]: This means the file: `~/.config/nixpkgs/config.nix`.
+
+In `.envrc`:
+
+```diff
+if ! has nix_direnv_version || ! nix_direnv_version 2.3.0; then
+  source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/2.3.0/direnvrc" "sha256-Dmd+j63L84wuzgyjITIfSxSD57Tx7v51DMxVZOsiUD8="
+fi
+use nix
+```
+
+It does a SHA validation to make sure that what it downloads matches
+what we think it does, which is a reasonable thing to do when loading
+scripts from the internet.
+
+On saving and quitting our editor, `direnv` will angrily state:
+
+```
+direnv: error /home/varl/dev/.envrc is blocked. Run `direnv allow` to approve its content
+```
+
+After another `direnv allow`, it will use cached developer environments,
+speeding up the time it takes to `cd` into a directory and setup the
+environment according to `shell.nix` by a lot.
+
+We can verify that by looking for lines like:
+
+```diff
+direnv: loading ~/dev/.envrc
+direnv: loading https://raw.githubusercontent.com/nix-community/nix-direnv/2.3.0/direnvrc (sha256-Dmd+j63L84wuzgyjITIfSxSD57Tx7v51DMxVZOsiUD8=)
+direnv: using nix
+direnv: nix-direnv: renewed cache
+```
+
+And:
+
+```diff
+direnv: loading ~/dev/.envrc
+direnv: loading https://raw.githubusercontent.com/nix-community/nix-direnv/2.3.0/direnvrc (sha256-Dmd+j63L84wuzgyjITIfSxSD57Tx7v51DMxVZOsiUD8=)
+direnv: using nix
+direnv: nix-direnv: using cached dev shell
+```
+
+## Shell hooks
+
+In our `shell.nix` above, notice that there is a `shellHook`[^4] directive
+that was empty. Let's see what we can use it for:
+
+```diff
+with (import <nixpkgs> {});
+
+mkShell {
+  buildInputs = [
+    nodejs-18_x
+    python3
+    python3.pkgs.pip
+    go_1_20
+    maven
+    jdk17
+  ];
+
+  shellHook = ''
+  '';
+}
+```
+
+[^4]: https://nixos.org/manual/nix/stable/command-ref/nix-shell#description
+
+`shellHook` is run _after_ the setup, so we can use it for
+initialisation that is specific for our `nix-shell`. For example, we can
+export environment variables to change things according to our context.
+
+We can use a specific browser profile to open links, a few examples I
+use is that we can change the `GOPATH` and `NODE_PATH`, or autoload Python
+`venvs`.
+
+```diff
+with (import <nixpkgs> {});
+
+mkShell {
+  buildInputs = [
+    nodejs-18_x
+    python3
+    python3.pkgs.pip
+    go_1_20
+    maven
+    jdk17
+  ];
+
+  shellHook = ''
+    # setup node
+    mkdir -p .nix-node
+    export NODE_PATH=$PWD/.nix-node
+    export NPM_CONFIG_PREFIX=$PWD/.nix-node
+
+    # setup python
+    mkdir -p .nix-python/venvs
+    xport SOURCE_DATE_EPOCH="$(date +%s)"
+    export VIRTUAL_ENV_DISABLE_PROMPT=1
+    export PIPENV_VERBOSITY=-1
+
+    if [ -f $PWD/.nix-python/venv/bin/activate ]; then
+      source $PWD/.nix-python/venv/bin/activate
+    fi
+
+    # setup go
+    mkdir -p .nix-go/{bin,pkg,src,cache}
+    touch .nix-go/env
+    export GOPATH=$PWD/.nix-go
+    export GOCACHE=$PWD/.nix-go/cache
+    export GOENV=$PWD/.nix-go/env
+  '';
+}
+```
+
+We could also do these things in `.envrc` (more or less), as both
+`direnv` and `nix-shell` ensures that it also unloads any environment
+variables we set up when we leave a directory, so they only exist in the
+context we are in.
+
+## Going a step further
+
+While what we have now is perfectly useful, the `~/dev/shell.nix` approach is not
+what I actually use.
+
+My setup looks more like:
+
+```
+~/dev% tree -L 2
+.
+├── work
+│   ├── apps
+│   │   ├── .envrc
+│   │   └── shell.nix
+│   ├── .envrc
+│   └── shell.nix
+├── forks
+│   ├── .envrc
+│   └── shell.nix
+├── personal
+│   ├── .envrc
+│   └── shell.nix
+├── .envrc
+└── shell.nix
+```
+
+With our current setup, each environment would fully overwrite the
+previous (so no nesting of environments, yet).
+
+## Nested developer environments
+
+Luckily, there is a handy feature in `direnv` that allows us to solve
+this by adding a single line to our `shell.nix` that we want to instruct
+to inherit from the parent `shell.nix`.
+
+If we want our `~/dev/work` environment to inherit from the parent
+`~/dev`, we put the following in `~/dev/work/.envrc`:
+
+```diff
+if ! has nix_direnv_version || ! nix_direnv_version 2.3.0; then
+  source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/2.3.0/direnvrc" "sha256-Dmd+j63L84wuzgyjITIfSxSD57Tx7v51DMxVZOsiUD8="
+fi
+source_up
+use nix
+```
+
+Now we can specify tools that are valid across all contexts in
+`~/dev/shell.nix`:
+
+```
+with (import <nixpkgs> {});
+
+mkShell {
+  buildInputs = [
+    yq
+    jq
+    gh
+    shellcheck
+    mr
+    tokei
+  ];
+
+  shellHook = ''
+    # empty so far
+  '';
+}
+```
+
+And get more specific, so for example for `~/dev/work/shell.nix`:
+
+```
+with (import <nixpkgs> {});
+
+mkShell {
+  buildInputs = [
+    nodejs-18_x
+    python3
+    python3.pkgs.pip
+    python3.pkgs.pex
+    kubectl
+    kustomize
+    (google-cloud-sdk.withExtraComponents [ google-cloud-sdk.components.gke-gcloud-auth-plugin ])
+    go_1_20
+    cloudflared
+    glibcLocales
+    maven
+    jdk17
+  ];
+
+  shellHook = ''
+    # ... truncated ...
+  '';
+}
+```
+
+For specific projects we can use nesting as an override feature, so we
+can swap `nodejs-18_x` for `nodejs-20_x` in specific projects, for
+example.
+
+I think that's about it for vol.3.
+
+/v.