Use Nix and put the CI for contributors

.envrc

@@ -0,0 +1 @@
+use flake

.github/workflows/ci-nix.yml

@@ -0,0 +1,24 @@
+name: CI - Nix
+on:
+  pull_request:
+    paths:
+      - '.github/workflows/ci-nix.yml'
+      - '*.nix'
+      - 'flake.*'
+  schedule:
+    # Every 10:42 JST
+    # https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#schedule
+    - cron: '42 1 * * *'
+  workflow_dispatch:
+
+jobs:
+  tasks:
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    steps:
+      - uses: actions/checkout@v3
+      - uses: DeterminateSystems/nix-installer-action@v4
+      - uses: DeterminateSystems/magic-nix-cache-action@v2
+      - run: nix flake check
+      - run: nix develop --command echo 'This step should be done before any other "nix develop" steps because of measuring Nix build time'
+      - run: nix develop --command make all

.gitignore

@@ -2,3 +2,4 @@ public
 .DS_Store
 **/.hugo_build.lock
 tmp
+.direnv/

.vscode/extensions.json

@@ -0,0 +1,10 @@
+{
+  "recommendations": [
+    "golang.go",
+    "github.vscode-github-actions",
+    "editorconfig.editorconfig",
+    "tekumara.typos-vscode",
+    "dprint.dprint",
+    "jnoortheen.nix-ide",
+  ]
+}

.vscode/settings.json

@@ -0,0 +1,10 @@
+{
+  "editor.defaultFormatter": "dprint.dprint",
+  "editor.formatOnSave": true,
+  "[nix]": {
+    "editor.defaultFormatter": "jnoortheen.nix-ide"
+  },
+  "[go]": {
+    "editor.defaultFormatter": "golang.go"
+  }
+}

flake.nix

@@ -0,0 +1,29 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/7fd307937db70af23b956c4539033542809ae263";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in
+      {
+        devShells.default = with pkgs;
+          mkShell {
+            buildInputs = [
+              hugo
+              go_1_20
+              gnumake
+              coreutils
+              peco
+              typos
+              dprint
+              actionlint
+              nil
+              nixpkgs-fmt
+            ];
+          };
+      });
+}