chore: Add Nix development files (#5856)

* chore: Add Nix development files

* chore: add dir env flakes support and add it's directory to gitignore

* chore: add shards

.envrc

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

.gitignore

@@ -7,3 +7,6 @@
 /invidious
 /sentry
 /config/config.yml
+
+# direnv directory used for the Nix Flake.
+.direnv

flake.lock

@@ -0,0 +1,61 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1785571196,
+        "narHash": "sha256-KoTsyMQqnXQZq8deCEnu4QkyldkwH/bpMMhUcfMdGIw=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "148bab9c1c3c53136ecb44a6ea356a0ed5b39b06",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,27 @@
+{
+  description = "Invidious Nix Flake";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs =
+    {
+      self,
+      nixpkgs,
+      flake-utils,
+    }:
+    flake-utils.lib.eachDefaultSystem (
+      system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+        devPackages = import ./packages.nix { inherit pkgs; };
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          buildInputs = devPackages;
+        };
+      }
+    );
+}

packages.nix

@@ -0,0 +1,19 @@
+{ pkgs }:
+
+# Development packages, this makes Crystal 1.19 (latest available in nixpkgs)
+# and sqlite available in a `nix-shell` or `nix develop` build environment.
+#
+# We dont need to add other dependencies like `libxml2` or `libyaml` here
+# since they are already available by default in the Crystal Nix package
+# (see the output value of CRYSTAL_LIBRARY_PATH when running `crystal env`
+# Ref: https://github.com/NixOS/nixpkgs/blob/nixos-26.05/pkgs/development/compilers/crystal/default.nix#L231)
+#
+with pkgs;
+[
+  # Invidious dependencies
+  crystal_1_19
+  sqlite
+  shards
+  # Utilities
+  nixd # Nixd LSP to format .nix files
+]

shell.nix

@@ -0,0 +1,11 @@
+{
+  pkgs ? import <nixpkgs> { },
+}:
+
+let
+  devPackages = import ./packages.nix { inherit pkgs; };
+in
+
+pkgs.mkShell {
+  buildInputs = devPackages;
+}