lint: add automatic linter to check config

.github/workflows/lint.yml

@@ -0,0 +1,26 @@
+---
+name: Lint
+
+on:
+  pull_request:
+  push:
+    branches:
+      - 'master'
+
+jobs:
+  lint:
+    name: Lint
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: cachix/install-nix-action@v25
+      with:
+        nix_path: nixpkgs=channel:nixos-unstable
+    - name: run lint scripts
+      run: |
+        for f in lint/lint_*.py; do
+          if ! python $f; then
+            echo "errors from $f ^^^^"
+            exit 1
+          fi
+        done

flake.nix

@@ -113,12 +113,12 @@
                 };
                 PORT = lib.mkOption {
                   type = lib.types.port;
-                  default = 48879;
-                  description = "Port to listen the webhook on. Defaults to 48879.";
+                  default = 51413;
+                  description = "Port to listen the webhook on. Defaults to 51413.";
                 };
                 WEBHOOK_URL = lib.mkOption {
                   type = lib.types.str;
-                  default = "https://${cfg.hostname}/${cfg.settings.TELEGRAM_API_KEY}";
+                  default = "https://${cfg.hostname}";
                   description = "The URL for the webhook. Defaults to hostname + api key.";
                 };
                 BACKGROUND_COLORS = lib.mkOption {

lint/lint_config.py

@@ -0,0 +1,126 @@
+#!/usr/bin/env python3
+
+"""Ensures config defined config parameters in config.py are identical to the ones in the NixOS module."""
+
+import ast
+import json
+import subprocess
+import sys
+from dataclasses import dataclass
+from pathlib import Path
+from typing import Any
+
+
+class NoDefault:
+    def __eq__(self, o: Any) -> bool:
+        return isinstance(o, NoDefault)
+
+    def __repr__(self) -> str:
+        return "@NO_DEFAULT@"
+
+
+class ComplicatedDefault:
+    def __eq__(self, o: Any) -> bool:
+        return isinstance(o, ComplicatedDefault)
+
+    def __repr__(self) -> str:
+        return "@COMPLICATED_DEFAULT@"
+
+
+@dataclass(eq=True, order=True)
+class ConfigKey:
+    key: str
+    default: Any
+
+
+def parse_config_keys(module: ast.Module) -> list[ConfigKey]:
+    keys: list[ConfigKey] = []
+
+    for child in ast.walk(module):
+        if isinstance(child, ast.Subscript):
+            # config[key]
+            if not isinstance(child.value, ast.Name) or child.value.id != "config":
+                continue
+
+            assert isinstance(child.slice, ast.Constant) and isinstance(child.slice.value, str)
+            keys.append(ConfigKey(child.slice.value, NoDefault()))
+        elif isinstance(child, ast.Call):
+            # config.get(key, ...)
+            if not isinstance(child.func, ast.Attribute) or child.func.attr != "get" or not isinstance(child.func.value, ast.Name) or child.func.value.id != "config":
+                continue
+
+            assert isinstance(child.args[0], ast.Constant) and isinstance(child.args[0].value, str)
+            if len(child.args) == 2:
+                # We have a default if we're here.
+                keys.append(ConfigKey(child.args[0].value, ast.literal_eval(child.args[1])))
+            else:
+                keys.append(ConfigKey(child.args[0].value, NoDefault()))
+
+    return keys
+
+
+def parse_nix_keys(flake_path: Path) -> list[ConfigKey]:
+    obj: dict[str, Any] = json.loads(subprocess.check_output([
+        "nix", "eval", "--impure", "--json", "--expr", f'builtins.getFlake "{flake_path}"', "--apply",
+        """flake: (
+            builtins.mapAttrs (name: value:
+                let eval = builtins.tryEval (value.default or { nodefault = true; });
+                in if eval.success then eval.value else { complicateddefault = true; }
+            ) (
+                builtins.elemAt (
+                    flake.outputs.nixosModules { lib = flake.inputs.nixpkgs.lib; config = throw "not full eval"; pkgs = {}; }).options.services.hu-cafeteria-bot.settings.type.getSubModules
+                    0
+                ).options
+            )"""
+    ], encoding="utf-8"))
+
+    keys: list[ConfigKey] = []
+    for key, default in obj.items():
+        if isinstance(default, dict):
+            if default.get("nodefault"):
+                keys.append(ConfigKey(key, NoDefault()))
+                continue
+            elif default.get("complicateddefault"):
+                keys.append(ConfigKey(key, ComplicatedDefault()))
+                continue
+        keys.append(ConfigKey(key, default))
+
+    return keys
+
+
+def main() -> bool:
+    config_path: Path = Path(__file__).parents[1] / "src" / "config.py"
+
+    config_keys: list[ConfigKey] = parse_config_keys(ast.parse(config_path.read_text()))
+    config_keys.sort(reverse=True)
+    config_key_set: set[str] = set(map(lambda c: c.key, config_keys))
+
+    nix_keys: list[ConfigKey] = parse_nix_keys(Path(__file__).parents[1])
+    nix_keys.sort(reverse=True)
+    nix_key_set: set[str] = set(map(lambda c: c.key, nix_keys))
+
+    if config_key_set != nix_key_set:
+        print("ERROR: Either config and nix keys are not same.")
+
+        if nix_key_set - config_key_set:
+            print("       Following keys are present in flake.nix but not in config.py:")
+            print("       - ", end="")
+            print(*(nix_key_set - config_key_set), sep=', ')
+
+        if config_key_set - nix_key_set:
+            print("       Following keys are present in config.py but not in flake.nix:")
+            print("       - ", end="")
+            print(*(config_key_set - nix_key_set), sep=', ')
+
+        return False
+
+    for (config_key, nix_key) in zip(config_keys, nix_keys):
+        if config_key.default != nix_key.default and nix_key.default != ComplicatedDefault():
+            print("ERROR: Default mismatch:", "key:", config_key.key, "config.py:", config_key.default, "flake.nix:", nix_key.default)
+            return False
+
+    return True
+
+
+if __name__ == "__main__":
+    sys.exit(int(not main()))