webui: implement /api/machines/{name}/schema

pkgs/clan-cli/clan_cli/config/machine.py

@@ -0,0 +1,47 @@
+import json
+import subprocess
+import sys
+from pathlib import Path
+from typing import Optional
+
+from ..dirs import get_clan_flake_toplevel
+
+
+def schema_for_machine(machine_name: str, flake: Optional[Path] = None) -> dict:
+    if flake is None:
+        flake = get_clan_flake_toplevel()
+    # use nix eval to read from .#clanModules.<module_name>.options
+    proc = subprocess.run(
+        [
+            "nix",
+            "eval",
+            "--json",
+            "--impure",
+            "--show-trace",
+            "--extra-experimental-features",
+            "nix-command flakes",
+            "--expr",
+            f"""
+            let
+                flake = builtins.getFlake (toString {flake});
+                lib = flake.inputs.nixpkgs.lib;
+                module = builtins.trace (builtins.attrNames flake) flake.clanModules.machine-{machine_name};
+                evaled = lib.evalModules {{
+                    modules = [module];
+                }};
+                clanOptions = evaled.options.clan;
+                jsonschemaLib = import {Path(__file__).parent / "jsonschema"} {{ inherit lib; }};
+                jsonschema = jsonschemaLib.parseOptions clanOptions;
+            in
+                jsonschema
+            """,
+        ],
+        capture_output=True,
+        text=True,
+    )
+    if proc.returncode != 0:
+        print(proc.stderr, file=sys.stderr)
+        raise Exception(
+            f"Failed to read schema for machine {machine_name}:\n{proc.stderr}"
+        )
+    return json.loads(proc.stdout)

pkgs/clan-cli/clan_cli/webui/routers/machines.py

@@ -2,6 +2,7 @@ from typing import Annotated
 
 from fastapi import APIRouter, Body
 
+from ...config.machine import schema_for_machine
 from ...machines.create import create_machine as _create_machine
 from ...machines.list import list_machines as _list_machines
 from ..schemas import (
@@ -11,7 +12,6 @@ from ..schemas import (
     MachineCreate,
     MachineResponse,
     MachinesResponse,
-    Schema,
     SchemaResponse,
     Status,
 )
@@ -54,5 +54,5 @@ async def set_machine_config(
 
 @router.get("/api/machines/{name}/schema")
 async def get_machine_schema(name: str) -> SchemaResponse:
-    print("TODO")
-    return SchemaResponse(schema=Schema())
+    schema = schema_for_machine(name)
+    return SchemaResponse(schema=schema)

pkgs/clan-cli/clan_cli/webui/schemas.py

@@ -34,9 +34,5 @@ class ConfigResponse(BaseModel):
     config: Config
 
 
-class Schema(BaseModel):
-    pass
-
-
 class SchemaResponse(BaseModel):
-    schema_: Schema = Field(alias="schema")
+    schema_: dict = Field(alias="schema")