feat: Devcontainer configuration for nix/direnv (#15)

Author: zah

.devcontainer/devcontainer.json

@@ -0,0 +1,8 @@
+{
+  "name": "codetracer-ruby-recorder",
+  "features": {
+    "ghcr.io/devcontainers/features/nix:1": {},
+    "ghcr.io/devcontainers-community/features/direnv:1": {}
+  },
+  "postCreateCommand": "direnv allow"
+}

.envrc

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

.gitignore

@@ -1,3 +1,5 @@
 *.json
+!.devcontainer/devcontainer.json
 !test/fixtures/*.json
 test/tmp/
+.direnv/

README.md

@@ -18,6 +18,12 @@ ruby trace.rb <path to ruby file>
 
 however you probably want to use it in combination with CodeTracer, which would be released soon.
 
+### Development
+
+This repository provides a Nix flake for the development shell. With direnv installed, the shell is loaded automatically when you enter the directory. Run `direnv allow` once to enable it.
+
+The same environment is configured for GitHub Codespaces via devcontainer configuration.
+
 ### env variables
 
 * if you pass `CODETRACER_RUBY_TRACER_DEBUG=1`, you enables some additional debug-related logging

flake.nix

@@ -0,0 +1,19 @@
+{
+  description = "Development environment for codetracer-ruby-recorder";
+
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05";
+
+  outputs = { self, nixpkgs }:
+    let
+      systems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
+      forEachSystem = nixpkgs.lib.genAttrs systems;
+    in {
+      devShells = forEachSystem (system:
+        let pkgs = import nixpkgs { inherit system; };
+        in {
+          default = pkgs.mkShell {
+            packages = with pkgs; [ ruby just ];
+          };
+        });
+    };
+}