Rewrite disko in Python

.envrc

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

.gitignore

@@ -1,4 +1,10 @@
 result
 
+disko-config.nix
+
+.direnv
+
+__pycache__/
+
 # Created by the NixOS interactive test driver
 .nixos-test-history

.vscode/extensions.json

@@ -0,0 +1,11 @@
+{
+  "recommendations": [
+    "mkhl.direnv",
+    "jnoortheen.nix-ide",
+    "ms-python.python",
+    "ms-python.debugpy",
+    "ms-python.mypy-type-checker",
+    "charliermarsh.ruff",
+    "ms-toolsai.jupyter"
+  ]
+}

.vscode/launch.json

@@ -0,0 +1,65 @@
+{
+  // Use IntelliSense to learn about possible attributes.
+  // Hover to view descriptions of existing attributes.
+  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "disko2 mount disko_file",
+      "type": "debugpy",
+      "request": "launch",
+      "module": "disko",
+      "env": {
+        "PYTHONPATH": "${workspaceFolder}/src"
+      },
+      "console": "integratedTerminal",
+      "args": [
+        "mount",
+        "example/simple-efi.nix"
+      ]
+    },
+    {
+      "name": "disko2 mount flake",
+      "type": "debugpy",
+      "request": "launch",
+      "module": "disko",
+      "env": {
+        "PYTHONPATH": "${workspaceFolder}/src"
+      },
+      "console": "integratedTerminal",
+      "args": [
+        "mount",
+        "--flake",
+        ".#testmachine"
+      ]
+    },
+    {
+      "name": "disko2 generate",
+      "type": "debugpy",
+      "request": "launch",
+      "module": "disko",
+      "env": {
+        "PYTHONPATH": "${workspaceFolder}/src"
+      },
+      "console": "integratedTerminal",
+      "args": [
+        "generate"
+      ]
+    },
+    {
+      "name": "disko2 destroy,format,mount dry-run",
+      "type": "debugpy",
+      "request": "launch",
+      "module": "disko",
+      "env": {
+        "PYTHONPATH": "${workspaceFolder}/src"
+      },
+      "console": "integratedTerminal",
+      "args": [
+        "destroy,format,mount",
+        "--dry-run",
+        "disko-config.nix"
+      ]
+    }
+  ]
+}

.vscode/settings.json

@@ -0,0 +1,27 @@
+{
+  "nix.serverSettings": {
+    "nixd": {
+      "formatting": {
+        "command": [
+          "nixpkgs-fmt",
+          "--"
+        ]
+      }
+    }
+  },
+  "cSpell.enabled": true,
+  "cSpell.words": [
+    "Disko",
+    "nixos",
+    "nixpkgs"
+  ],
+  "python.analysis.extraPaths": [
+    "./src"
+  ],
+  "mypy-type-checker.importStrategy": "fromEnvironment",
+  "python.testing.pytestArgs": [
+    "tests"
+  ],
+  "python.testing.unittestEnabled": false,
+  "python.testing.pytestEnabled": true
+}

CONTRIBUTING.md

@@ -12,6 +12,9 @@ way to help us fix issues quickly. Check out
 For more information on how to run and debug tests, check out
 [Running and debugging tests](./docs/testing.md).
 
+Also refer to [Setting up your development environment](./dev-setup.md) to get
+the best possible development experience.
+
 ## How to find issues to work on
 
 If you're looking for a low-hanging fruit, check out

default.nix

@@ -1,44 +1,8 @@
 { lib ? import <nixpkgs/lib>
 , rootMountPoint ? "/mnt"
 , checked ? false
-, diskoLib ? import ./lib { inherit lib rootMountPoint; }
+, diskoLib ? import ./src/disko_lib { inherit lib rootMountPoint; }
 }:
-let
-  eval = cfg: lib.evalModules {
-    modules = lib.singleton {
-      # _file = toString input;
-      imports = lib.singleton { disko.devices = cfg.disko.devices; };
-      options = {
-        disko.devices = lib.mkOption {
-          type = diskoLib.toplevel;
-        };
-      };
-    };
-  };
-in
-{
-  lib = lib.warn "the .lib.lib output is deprecated" diskoLib;
-
-  # legacy alias
-  create = cfg: builtins.trace "the create output is deprecated, use format instead" (eval cfg).config.disko.devices._create;
-  createScript = cfg: pkgs: builtins.trace "the create output is deprecated, use format instead" ((eval cfg).config.disko.devices._scripts { inherit pkgs checked; }).formatScript;
-  createScriptNoDeps = cfg: pkgs: builtins.trace "the create output is deprecated, use format instead" ((eval cfg).config.disko.devices._scripts { inherit pkgs checked; }).formatScriptNoDeps;
-
-  format = cfg: (eval cfg).config.disko.devices._create;
-  formatScript = cfg: pkgs: ((eval cfg).config.disko.devices._scripts { inherit pkgs checked; }).formatScript;
-  formatScriptNoDeps = cfg: pkgs: ((eval cfg).config.disko.devices._scripts { inherit pkgs checked; }).formatScriptNoDeps;
-
-  mount = cfg: (eval cfg).config.disko.devices._mount;
-  mountScript = cfg: pkgs: ((eval cfg).config.disko.devices._scripts { inherit pkgs checked; }).mountScript;
-  mountScriptNoDeps = cfg: pkgs: ((eval cfg).config.disko.devices._scripts { inherit pkgs checked; }).mountScriptNoDeps;
-
-  disko = cfg: (eval cfg).config.disko.devices._disko;
-  diskoScript = cfg: pkgs: ((eval cfg).config.disko.devices._scripts { inherit pkgs checked; }).diskoScript;
-  diskoScriptNoDeps = cfg: pkgs: ((eval cfg).config.disko.devices._scripts { inherit pkgs checked; }).diskoScriptNoDeps;
-
-  # we keep this old output for backwards compatibility
-  diskoNoDeps = cfg: pkgs: builtins.trace "the diskoNoDeps output is deprecated, please use disko instead" ((eval cfg).config.disko.devices._scripts { inherit pkgs checked; }).diskoScriptNoDeps;
-
-  config = cfg: (eval cfg).config.disko.devices._config;
-  packages = cfg: (eval cfg).config.disko.devices._packages;
+diskoLib.outputs {
+  inherit lib checked rootMountPoint;
 }

disko

@@ -153,7 +153,7 @@ else
 fi
 
 # The "--impure" is still pure, as the path is within the nix store.
-script=$(nixBuild "${libexec_dir}"/cli.nix \
+script=$(nixBuild "${libexec_dir}"/src/cli.nix \
   --no-out-link \
   --impure \
   --argstr mode "$mode" \

disko-install

@@ -197,7 +197,7 @@ main() {
   # shellcheck disable=SC2064
   trap "cleanupMountPoint ${escapeMountPoint}" EXIT
 
-  outputs=$(nixBuild "${libexec_dir}"/install-cli.nix \
+  outputs=$(nixBuild "${libexec_dir}"/src/install-cli.nix \
     "${nix_args[@]}" \
     --no-out-link \
     --impure \

disko2

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+# This script only exists so you can run `./disko2` directly
+# It should not be be installed as part of the package!
+# Check src/disko/cli.py for the actual entrypoint
+
+set -euo pipefail
+PYTHONPATH="$(dirname "$(realpath "$0")")"/src python3 -m disko "$@"

doc.nix

@@ -1,7 +1,7 @@
 { lib, nixosOptionsDoc, runCommand, fetchurl, pandoc }:
 
 let
-  diskoLib = import ./lib {
+  diskoLib = import ./src/disko_lib {
     inherit lib;
     rootMountPoint = "/mnt";
   };

docs/INDEX.md

@@ -19,4 +19,5 @@
 
 ### For contributors
 
+- [Setting up your development environment](./dev-setup.md)
 - [Running and debugging tests](./testing.md)

docs/dev-setup.md

@@ -0,0 +1,75 @@
+# Setting up your development environment
+
+**This guide assumes you have flakes enabled.**
+
+disko uses Nix flake's `devShells` output and [direnv](https://direnv.net/) to
+set up the development environment in two ways.
+
+The quickest way to get started is to run:
+
+```
+nix develop
+```
+
+However, if you use a shell other than bash, working inside `nix develop` might
+get annoying quickly. An alternative is to use direnv, which sets up the
+environment in your current shell session:
+
+```console
+# nix shell nixpkgs#direnv
+direnv: error /home/felix/repos-new/temp/disko/.envrc is blocked. Run `direnv allow` to approve its content
+# direnv allow
+direnv: loading ~/repos-new/temp/disko/.envrc
+direnv: using flake
+direnv: export +AR +AS +CC +CONFIG_SHELL +CXX +HOST_PATH +IN_NIX_SHELL +LD +NIX_BINTOOLS +NIX_BINTOOLS_WRAPPER_TARGET_HOST_x86_64_unknown_linux_gnu +NIX_BUILD_CORES +NIX_BUILD_TOP +NIX_CC +NIX_CC_WRAPPER_TARGET_HOST_x86_64_unknown_linux_gnu +NIX_CFLAGS_COMPILE +NIX_ENFORCE_NO_NATIVE +NIX_HARDENING_ENABLE +NIX_LDFLAGS +NIX_STORE +NM +OBJCOPY +OBJDUMP +RANLIB +READELF +SIZE +SOURCE_DATE_EPOCH +STRINGS +STRIP +TEMP +TEMPDIR +TMP +TMPDIR +__structuredAttrs +buildInputs +buildPhase +builder +cmakeFlags +configureFlags +depsBuildBuild +depsBuildBuildPropagated +depsBuildTarget +depsBuildTargetPropagated +depsHostHost +depsHostHostPropagated +depsTargetTarget +depsTargetTargetPropagated +doCheck +doInstallCheck +dontAddDisableDepTrack +mesonFlags +name +nativeBuildInputs +out +outputs +patches +phases +preferLocalBuild +propagatedBuildInputs +propagatedNativeBuildInputs +shell +shellHook +stdenv +strictDeps +system ~PATH ~XDG_DATA_DIRS
+```
+
+You can now run `./disko2 dev --help` or `pytest` to confirm everything is working.
+
+If you're working exclusively in the terminal, you're all set.
+
+## IDE Integration
+
+### VSCode
+
+If you're using VSCode or any of its forks, you should install the recommended
+extensions. You can find them in .vscode/extensions.json, searching for
+`@recommended` in the Extensions Panel, or by opening the
+command pallette and searching "Show Recommended Extensions".
+
+You can then install all extensions in one click:
+
+![VSCode button "Install workspace recommended extensions](./img/vscode-recommended-ext.png)
+
+When you do this (and every time you open the repository again), the
+[direnv extension](https://marketplace.visualstudio.com/items?itemName=mkhl.direnv)
+will prompt you in the bottom right corner to restart all extensions once it
+has loaded the development environment:
+
+![Direnv extension asking "Environment updated. Restart extensions?"](./img/vscode-direnv-prompt.png)
+
+Click "Restart" to make all dependencies available to VSCode.
+
+Afterwards, open the command pallette, search "Python: Select Interpreter" and
+press Enter. The "Select Interpreter" dialog will open:
+
+![VSCode Python "Select Interpreter" dialog](./img/vscode-select-python.png)
+
+Do not select the interpreters tagged "Recommended" or "Global"! These will be
+the ones installed on your system or currently selected in the extension.
+Instead, pick one of the ones below them, this will be the latest available
+package that includes the python packages specified in the `devShell`!
+
+Now you're all set! You might want to also enable the "Format on Save" settings
+and run the "Format Document" command once to select a formatter for each file
+type.
+
+Remember to go through these steps again whenever updating the flake.
+
+### Other IDEs
+
+These are just notes. Feel free to submit a PR that adds support and
+documentation for other IDEs!
+
+[Jetbrains Marketplace has two direnv extensions available](https://plugins.jetbrains.com/search?excludeTags=internal&search=direnv)
+

docs/reference.md

@@ -4,7 +4,7 @@
 
 We are currently having issues being able to generate proper module option
 documentation for our recursive disko types. However you can read the available
-options [here](https://github.com/nix-community/disko/tree/master/lib/types).
+options [here](https://github.com/nix-community/disko/tree/master/src/disko_lib/types).
 Combined with the
 [examples](https://github.com/nix-community/disko/tree/master/example) this
 hopefully gives you an overview.

docs/testing.md

@@ -1,20 +1,35 @@
 # Running and debugging tests
 
+This assumes you've already set up your development environment!
+
+See [Setting up your development environment](./dev-setup.md)
+
+## Python tests
+
+Big parts of disko are written in Python. You can test all Python
+functionality by simply running
+
+```
+pytest
+```
+
+## VM tests
+
 Disko makes extensive use of VM tests. All examples you can find in
 [the example directory](../example) have a respective test suite that verifies
 the example is working in [the tests directory](../tests/). They utilize the
 [NixOS test functionality](https://nixos.org/manual/nixos/stable/#sec-nixos-tests).
 
 We use a wrapper around this called `makeDiskoTest`. There is currently (as of
 2024-10-16) no documentation for all its arguments, but you can have a look at
-[its current code](https://github.com/nix-community/disko/blob/master/lib/tests.nix#L44C5-L58C10),
+[its current code](https://github.com/nix-community/disko/blob/master/src/disko_lib/tests.nix#L44C5-L58C10),
 that should already be helpful.
 
 However, you don't need to know about all of the inner workings to interact with
 the tests effectively. For some of the most common operations, see the sections
 below.
 
-## Run just one of the tests
+### Run just one of the tests
 
 ```sh
 nix build --no-link .#checks.x86_64-linux.simple-efi
@@ -27,7 +42,7 @@ virtual devices, run disko to format them, reboot, verify the VM boots properly,
 and then run the code specified in `extraTestScript` to validate that the
 partitions have been created and were mounted as expected.
 
-### How `extraTestScript` works
+#### How `extraTestScript` works
 
 This is written in Python. The most common lines you'll see look something like
 this:
@@ -45,7 +60,7 @@ Disko currently (as of 2024-10-16) doesn't have any tests that utilize multiple
 VMs at once, so the only machine available in these scripts is always just the
 default `machine`.
 
-## Debugging tests
+### Debugging tests
 
 If you make changes to disko, you might break a test, or you may want to modify
 a test to prevent regressions. In these cases, running the full test with
@@ -131,7 +146,7 @@ vdb    253:16   0    4G  0 disk
 You can find some additional details in
 [the NixOS manual's section on interactive testing](https://nixos.org/manual/nixos/stable/#sec-running-nixos-tests-interactively).
 
-## Running all tests at once
+### Running all tests at once
 
 If you have a bit of experience, you might be inclined to run `nix flake check`
 to run all tests at once. However, we instead recommend using