Validate devenv.yaml schema and move overlays to inputs

docs/reference/yaml-options.md

@@ -6,8 +6,9 @@
 | inputs.<name>           | Identifier name used when passing the input in your ``devenv.nix`` function.  |
 | inputs.<name>.url       | URI specification of the input, see below for possible values.                |
 | inputs.<name>.flake     | Does the input contain ``flake.nix`` or ``devenv.nix``. Defaults to ``true``. |
+| inputs.<name>.overlays  | A list of overlays to include from the input. |
 | imports                       | A list of relative paths or references to inputs to import ``devenv.nix``.    |
-| overlays                      | Names of inputs with a list of overlays to include.                           |
+
 
 ## inputs.<name>.url
 

examples/overlays/devenv.yaml

@@ -1,9 +1,8 @@
+allowUnfree: true
 inputs:
   nixpkgs:
     url: github:NixOS/nixpkgs/nixpkgs-unstable
   rust-overlay:
     url: github:oxalica/rust-overlay
-allowUnfree: true
-overlays:
-  rust-overlay:
-   - default
+    overlays:
+      - default

src/devenv-yaml.nix

@@ -0,0 +1,43 @@
+{ pkgs }:
+
+pkgs.writers.writePython3Bin "devenv-yaml" { libraries = with pkgs.python3Packages; [ strictyaml path ]; } ''
+  from strictyaml import Map, MapPattern, Str, Seq
+  from strictyaml import load, Bool, Any, Optional, YAMLError
+  import json
+  import sys
+  import os
+  from path import Path
+
+  inputsSchema = MapPattern(Str(), Map({
+      "url": Str(),
+      Optional("flake", default=None): Bool(),
+      Optional("inputs", default=None): Any(),
+      Optional("overlays", default=None): Seq(Str())
+  }))
+
+  schema = Map({
+      Optional("inputs", default=None): inputsSchema,
+      Optional("allowUnfree", default=False): Bool(),
+      Optional("imports", default=None): Seq(Str())
+  })
+
+  filename = Path("devenv.yaml").bytes().decode('utf8')
+  try:
+      devenv = load(filename, schema, label="devenv.yaml").data
+  except YAMLError as error:
+      print("Error in `devenv.yaml`", error)
+      sys.exit(1)
+
+  inputs = {}
+  for input, attrs in devenv['inputs'].items():
+      inputs[input] = {k: attrs[k] for k in ('url', 'inputs', 'flake')
+                       if k in attrs}
+
+  devenv_state = sys.argv[1]
+
+  with open(os.path.join(devenv_state, "flake.json"), 'w') as f:
+      f.write(json.dumps(inputs))
+
+  with open(os.path.join(devenv_state, "devenv.json"), 'w') as f:
+      f.write(json.dumps(devenv))
+''

src/devenv.nix

@@ -29,11 +29,11 @@ pkgs.writeScriptBin "devenv" ''
     export DEVENV_DIR="$(pwd)/.devenv"
     export DEVENV_GC="$DEVENV_DIR/gc"
     mkdir -p "$DEVENV_GC"
-    # TODO: validate devenv.yaml using jsonschema
     if [[ -f devenv.yaml ]]; then
-      cat devenv.yaml | ${pkgs.yaml2json}/bin/yaml2json > "$DEVENV_DIR/devenv.json"
+      ${import ./devenv-yaml.nix { inherit pkgs; }}/bin/devenv-yaml "$DEVENV_DIR"
     else
       [[ -f "$DEVENV_DIR/devenv.json" ]] && rm "$DEVENV_DIR/devenv.json"
+      [[ -f "$DEVENV_DIR/flake.json" ]] && rm "$DEVENV_DIR/flake.json"
     fi
     cp -f ${import ./flake.nix { inherit pkgs version; }} "$FLAKE_FILE"
     chmod +w "$FLAKE_FILE"

src/flake.nix

@@ -5,20 +5,21 @@
       pre-commit-hooks.inputs.nixpkgs.follows = "nixpkgs";
       nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
       devenv.url = "github:cachix/devenv?dir=src/modules";
-    } // (if builtins.pathExists ./.devenv/devenv.json 
-         then (builtins.fromJSON (builtins.readFile ./.devenv/devenv.json)).inputs
+    } // (if builtins.pathExists ./.devenv/flake.json 
+         then builtins.fromJSON (builtins.readFile ./.devenv/flake.json)
          else {});
 
     outputs = { nixpkgs, ... }@inputs:
       let
         devenv = if builtins.pathExists ./.devenv/devenv.json
           then builtins.fromJSON (builtins.readFile ./.devenv/devenv.json)
           else {};
-        getOverlays = inputName: overlays:
-          map (overlay: let 
+        getOverlays = inputName: inputAttrs:
+          map (overlay: let
               input = inputs.''${inputName} or (throw "No such input `''${inputName}` while trying to configure overlays.");
-            in input.overlays.''${overlay} or (throw "Input `''${inputName}` has no overlay called `''${overlay}`. Supported overlays: ''${nixpkgs.lib.concatStringsSep ", " (builtins.attrNames input.overlays)}")) overlays;
-        overlays = nixpkgs.lib.flatten (nixpkgs.lib.mapAttrsToList getOverlays (devenv.overlays or {}));
+            in input.overlays.''${overlay} or (throw "Input `''${inputName}` has no overlay called `''${overlay}`. Supported overlays: ''${nixpkgs.lib.concatStringsSep ", " (builtins.attrNames input.overlays)}"))
+            inputAttrs.overlays or [];
+        overlays = nixpkgs.lib.flatten (nixpkgs.lib.mapAttrsToList getOverlays (devenv.inputs or {}));
         pkgs = import nixpkgs {
           system = "${pkgs.system}";
           allowUnfree = devenv.allowUnfree or false;