Migrate nix environment to flakes (#604)

* 🚧 WIP: migrating to flakes

* re-add commands

* darwin-only packages

* clean up a bunch of unused stack-to-nix stuff

* --nix-pure is working now?

* ditch lorri

* add cachix + note

* remove redundant --nix from commands

* tweak github actions cache

* action cache busting

.envrc

@@ -1 +1 @@
-eval "$(lorri direnv)"
+use flake

.github/workflows/artifacts-nix.yaml

@@ -17,33 +17,33 @@ jobs:
           - ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
-      name: 📤 Checkout
-      if: github.event.action == 'opened' || github.event.action == 'synchronize' || github.event.ref == 'refs/heads/main'
-
-    - uses: cachix/install-nix-action@v16
-      name: ❄️  Set up Nix
-      with:
-        nix_path: nixpkgs=channel:nixos-unstable
-
-    - uses: actions/cache@v2
-      name: 🗄️  Cache ~/.stack
-      with:
-        path: ~/.stack
-        key: ${{ matrix.os }}-stack-nix-4
-
-    - name: 🏗️  Build
-      run: |
-        nix-shell --command build
-
-    - name: 🏺 Upload CLI Artifact
-      uses: actions/upload-artifact@v2
-      with:
-        name: fission-cli-${{ matrix.os }}-nix
-        path: ./.stack-work/**/*-nix/**/bin/fission
-
-    - name: 🏺 Upload Server Artifact
-      uses: actions/upload-artifact@v2
-      with:
-        name: fission-server-${{ matrix.os }}-nix
-        path: ./.stack-work/**/*-nix/**/bin/fission-server
+      - uses: actions/checkout@v2
+        name: 📤 Checkout
+        if: github.event.action == 'opened' || github.event.action == 'synchronize' || github.event.ref == 'refs/heads/main'
+
+      - uses: cachix/install-nix-action@v16
+        name: ❄️  Set up Nix
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+
+      - uses: actions/cache@v2
+        name: 🗄️  Cache ~/.stack
+        with:
+          path: ~/.stack
+          key: ${{ matrix.os }}-stack-nix-${{ hashFiles('stack.yaml.lock') }}
+
+      - name: 🏗️  Build
+        run: |
+          nix-shell --command build
+
+      - name: 🏺 Upload CLI Artifact
+        uses: actions/upload-artifact@v2
+        with:
+          name: fission-cli-${{ matrix.os }}-nix
+          path: ./.stack-work/**/*-nix/**/bin/fission
+
+      - name: 🏺 Upload Server Artifact
+        uses: actions/upload-artifact@v2
+        with:
+          name: fission-server-${{ matrix.os }}-nix
+          path: ./.stack-work/**/*-nix/**/bin/fission-server

.github/workflows/ci-nix.yaml

@@ -17,21 +17,21 @@ jobs:
           - ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
-      name: 📤 Checkout
-      if: github.event.action == 'opened' || github.event.action == 'synchronize' || github.event.ref == 'refs/heads/main'
+      - uses: actions/checkout@v2
+        name: 📤 Checkout
+        if: github.event.action == 'opened' || github.event.action == 'synchronize' || github.event.ref == 'refs/heads/main'
 
-    - uses: cachix/install-nix-action@v16
-      name: ❄️  Set up Nix
-      with:
-        nix_path: nixpkgs=channel:nixos-unstable
+      - uses: cachix/install-nix-action@v16
+        name: ❄️  Set up Nix
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
 
-    - uses: actions/cache@v2
-      name: 🗄️  Cache ~/.stack
-      with:
-        path: ~/.stack
-        key: ${{ matrix.os }}-stack-nix-ci-4
+      - uses: actions/cache@v2
+        name: 🗄️  Cache ~/.stack
+        with:
+          path: ~/.stack
+          key: ${{ matrix.os }}-stack-nix-${{ hashFiles('stack.yaml.lock') }}
 
-    - name: 🧪 Test
-      run: |
-        nix-shell --command quality
+      - name: 🧪 Test
+        run: |
+          nix-shell --command quality

.gitignore

@@ -590,3 +590,4 @@ MigrationBackup/
 
 fission-web-server/data/
 fission-web-server/.env
+.direnv/

README.md

@@ -48,3 +48,5 @@ Web server, database, 3rd party integrations
 # Building
 
 Fission is built inside of a pure Nix shell via the [Stack integration](https://docs.haskellstack.org/en/stable/nix_integration/). This means that you _should_ only need to type `stack build` to do a complete build of all packages.
+
+If you're using a nix shell, you can use `cachix` to prevent re-building dependencies (particularly on `aarch64-darwin`) via: `cachix use fission-codes`.

default.nix

@@ -1,15 +1,13 @@
-{ haskellNixSrc ? builtins.fetchTarball https://github.com/input-output-hk/haskell.nix/archive/master.tar.gz
-}:
-
-let
-  haskellNix = import haskellNixSrc { };
-  pkgs = import haskellNix.sources.nixpkgs-unstable haskellNix.nixpkgsArgs;
-
-  pkgSet = pkgs.haskell-nix.mkStackPkgSet {
-    stack-pkgs = import ./nix/pkgs.nix;
-    pkg-def-extras = [];
-    modules = [];
-  };
-
-in
-  pkgSet.config.hsPkgs
+(import
+  (
+    let
+      lock = builtins.fromJSON (builtins.readFile ./flake.lock);
+    in
+    fetchTarball {
+      url = "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
+      sha256 = lock.nodes.flake-compat.locked.narHash;
+    }
+  )
+  {
+    src = ./.;
+  }).defaultNix

flake.nix

@@ -0,0 +1,67 @@
+{
+  description = "Fission tools";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/release-22.05";
+    flake-utils.url = "github:numtide/flake-utils";
+
+    flake-compat = {
+      url = "github:edolstra/flake-compat";
+      flake = false;
+    };
+  };
+
+  outputs = { self, nixpkgs, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem
+      (system:
+        let
+
+          pkgs = nixpkgs.legacyPackages.${system};
+
+          # Inspired by https://www.tweag.io/blog/2022-06-02-haskell-stack-nix-shell/
+          stack-wrapped = pkgs.symlinkJoin {
+            name = "stack";
+            paths = [ pkgs.stack ];
+            buildInputs = [ pkgs.makeWrapper ];
+            postBuild = ''
+              wrapProgram $out/bin/stack \
+                --add-flags "\
+                  --nix \
+                  --nix-pure \
+                  --nix-shell-file=nix/stack-integration.nix \
+                "
+            '';
+          };
+
+          # Wrapper commands for convenience
+          commands = import ./nix/commands.nix;
+          server-path = "~/.local/bin/fission-server";
+          tasks = commands {
+            inherit pkgs;
+            inherit server-path;
+            inherit stack-wrapped;
+          };
+
+          # The default version of HLS (with binary cache) is built with GHC 9.0.1
+          # We can get this version working with our current set up, but it builds 
+          # from source (and takes a long time).
+          #
+          # The prebuilt package is marked as broken on aarch64-darwin
+          haskellPackages = pkgs.haskell.packages.ghc8107;
+        in
+        {
+          devShells.default = pkgs.mkShell {
+            name = "fission";
+            buildInputs = [
+              stack-wrapped
+              haskellPackages.haskell-language-server
+              pkgs.cachix
+              pkgs.nixpkgs-fmt
+              pkgs.stylish-haskell
+              tasks
+            ];
+            NIX_PATH = "nixpkgs=" + pkgs.path;
+          };
+        }
+      );
+}