nix: Simplify and comment flake.nix

fossar · Dec 18, 2020 · f0367a9 · f0367a9
1 parent 7a3a611
commit f0367a9
Show file tree

Hide file tree

Showing 2 changed files with 45 additions and 25 deletions.
diff --git a/.travis.yml b/.travis.yml
@@ -38,7 +38,7 @@ before_install:
     - nix path-info --all > /tmp/store-path-pre-build
 
     # Update flake.nix to match the current CI job from matrix.
-    - sed -i "s/matrix.php = \"php\";/matrix.php = \"php${PHP}\";/" flake.nix
+    - sed -i "s/matrix.phpPackage = \"php\";/matrix.phpPackage = \"php${PHP}\";/" flake.nix
 
     - if [ -n "$GH_TOKEN" ]; then nix-shell --run "composer config github-oauth.github.com ${GH_TOKEN}"; fi
 

diff --git a/flake.nix b/flake.nix
@@ -2,60 +2,80 @@
   description = "selfoss feed reader and aggregator";
 
   inputs = {
+    # Shim to make flake.nix work with stable Nix.
     flake-compat = {
       url = "github:edolstra/flake-compat";
       flake = false;
     };
 
+    # Repository with software packages.
     nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
 
     utils.url = "github:numtide/flake-utils";
   };
 
   outputs = { self, flake-compat, nixpkgs, utils }:
     let
-      matrix.php = "php";
+      # Configure the development shell here (e.g. for CI).
 
-      mkDevShell = pkgs: phpPackage:
+      # By default, we use the default PHP version from Nixpkgs.
+      matrix.phpPackage = "php";
+    in
+      # For each supported platform,
+      utils.lib.eachDefaultSystem (system:
         let
-          php = pkgs.${phpPackage}.withExtensions ({ enabled, all }: with all; enabled ++ [
+          # Let’s merge the package set from Nixpkgs with our custom PHP versions.
+          pkgs = import nixpkgs.outPath {
+            inherit system;
+            overlays = [
+              (import ./utils/nix/phps.nix nixpkgs.outPath)
+            ];
+          };
+
+          # Create a PHP package from the selected PHP package, with some extra extensions enabled.
+          php = pkgs.${matrix.phpPackage}.withExtensions ({ enabled, all }: with all; enabled ++ [
             imagick
           ]);
 
+          # Create a Python package with some extra packages installed.
           python = pkgs.python3.withPackages (pp: with pp; [
-            requests
+            # For integration tests.
             bcrypt
+            requests
           ]);
-        in
-          pkgs.mkShell {
+        in {
+          # Expose shell environment for development.
+          devShell = pkgs.mkShell {
             nativeBuildInputs = [
+              # Composer and PHP for back-end.
               php
-              pkgs.zola
+              php.packages.composer
+
+              # Back-end code validation.
+              php.packages.psalm
+              php.packages.phpstan
+
+              # npm for front-end.
               pkgs.nodejs_latest
-              python
+
+              # For building zip archive.
               pkgs.jq
-            ] ++ (with php.packages; [
-              composer
-              psalm
-              phpstan
-            ]);
 
-            LOCALE_ARCHIVE = "${pkgs.glibcLocales}/lib/locale/locale-archive";
-          };
-    in
-      utils.lib.eachDefaultSystem (system:
-        let
-          pkgs = import nixpkgs.outPath {
-            inherit system;
-            overlays = [
-              (import ./utils/nix/phps.nix nixpkgs.outPath)
+              # For building zip archive and integration tests.
+              python
+
+              # Website generator.
+              pkgs.zola
             ];
+
+            # node-gyp wants some locales, let’s make them available through an environment variable.
+            LOCALE_ARCHIVE = "${pkgs.glibcLocales}/lib/locale/locale-archive";
           };
-        in {
+
+          # Expose our custom PHP packages for testing.
           packages = {
             inherit (pkgs) php56 php70 php71 php72;
           };
-          devShell = mkDevShell pkgs matrix.php;
         }
       );
 }