Merge pull request #60 from renan-r-santos/configurable_fallback_env

Add support for configurable fallback environment

Author: renan-r-santos

README.md

@@ -50,6 +50,10 @@ environment, use JupyterLab property inspector, save your notebook and restart y
 
 ![JupyterLab property inspector showing Pixi environment selector](https://raw.githubusercontent.com/renan-r-santos/pixi-kernel/main/assets/env-selector-light.png)
 
+If an environment cannot be determined, Pixi kernel will fallback to the value in the
+`PIXI_KERNEL_DEFAULT_ENVIRONMENT` environment variable, if specified. Otherwise, the `default` Pixi
+environment will be used.
+
 ## JupyterHub deployments with limited permissions
 
 If you're using pixi-kernel on JupyterHub and cannot access the environment where JupyterLab is

pixi_kernel/env.py

@@ -6,7 +6,7 @@
 from .async_subprocess import subprocess_exec
 from .types import PixiInfo
 
-DEFAULT_ENVIRONMENT_NAME = "default"
+DEFAULT_ENVIRONMENT = "default"
 
 
 async def envs_from_path(path: Path) -> list[str]:
@@ -17,14 +17,14 @@ async def envs_from_path(path: Path) -> list[str]:
 
     returncode, stdout, stderr = await subprocess_exec("pixi", "info", "--json", cwd=path, env=env)
     if returncode != 0:
-        return [DEFAULT_ENVIRONMENT_NAME]
+        return [DEFAULT_ENVIRONMENT]
 
     try:
         pixi_info = PixiInfo.model_validate_json(stdout, strict=True)
     except ValidationError:
-        return [DEFAULT_ENVIRONMENT_NAME]
+        return [DEFAULT_ENVIRONMENT]
 
     if len(pixi_info.environments) == 0:
-        return [DEFAULT_ENVIRONMENT_NAME]
+        return [DEFAULT_ENVIRONMENT]
 
-    return [env.name for env in pixi_info.environments]
+    return sorted([env.name for env in pixi_info.environments])

pixi_kernel/handlers.py

@@ -1,4 +1,5 @@
 import json
+import os
 from pathlib import Path
 
 import tornado
@@ -8,7 +9,7 @@
 from returns.result import Failure
 
 from .compatibility import has_compatible_pixi
-from .env import envs_from_path
+from .env import DEFAULT_ENVIRONMENT, envs_from_path
 
 
 class EnvHandler(APIHandler):
@@ -30,7 +31,13 @@ async def post(self) -> None:
             notebook_path = notebook_path.parent
 
         envs = await envs_from_path(notebook_path)
-        await self.finish(json.dumps(envs))
+
+        default_env = os.environ.get("PIXI_KERNEL_DEFAULT_ENVIRONMENT")
+        if default_env not in envs:
+            default_env = DEFAULT_ENVIRONMENT
+
+        response = {"environments": envs, "default": default_env}
+        await self.finish(json.dumps(response))
 
 
 def setup_handlers(web_app: ServerWebApplication) -> None:

pixi_kernel/provisioner.py

@@ -44,32 +44,27 @@ async def pre_launch(self, **kwargs: Any) -> dict[str, Any]:
 
         env: dict[str, str] = kwargs.get("env", os.environ.copy())
 
+        # If a new notebook is saved with the Pixi-kernel environment selection panel opened, the
+        # environment field in the Notebook metadata could become an empty string.
+        # https://github.com/renan-r-santos/pixi-kernel/issues/43#issuecomment-2676320749
+        environment_name = ""
+
         # https://github.com/jupyterlab/jupyterlab/issues/16282
         notebook_path = env.get("JPY_SESSION_NAME")
         if notebook_path is None:
-            self.log.error(
-                "Failed to get notebook path from JPY_SESSION_NAME variable."
-                "Falling back to the default environment."
-            )
-            environment_name = "default"
+            self.log.error("Failed to get notebook path from JPY_SESSION_NAME variable.")
         else:
             try:
                 # Set encoding to utf-8 to avoid issues on Windows
                 # https://github.com/renan-r-santos/pixi-kernel/issues/55
                 notebook = json.loads(Path(notebook_path).read_text(encoding="utf-8"))
                 environment_name = notebook["metadata"]["pixi-kernel"]["environment"]
             except Exception:
-                self.log.exception(
-                    "Failed to get Pixi environment name from notebook metadata."
-                    "Falling back to default environment."
-                )
-                environment_name = "default"
+                self.log.exception("Failed to get Pixi environment name from notebook metadata.")
 
-        # If a new notebook is saved with the Pixi-kernel environment selection panel opened, the
-        # environment field in the Notebook metadata could become an empty string.
-        # https://github.com/renan-r-santos/pixi-kernel/issues/43#issuecomment-2676320749
         if environment_name == "":
-            environment_name = "default"
+            environment_name = os.environ.get("PIXI_KERNEL_DEFAULT_ENVIRONMENT", "default")
+            self.log.info(f"Falling back to the '{environment_name}' Pixi environment.")
 
         result = await verify_env_readiness(
             environment_name=environment_name,

src/env.tsx

@@ -11,8 +11,14 @@ interface IPixiEnvProps extends WidgetProps {
   nbTracker: INotebookTracker;
 }
 
+interface IEnvironmentResponse {
+  environments: string[];
+  default: string;
+}
+
 export const PixiEnvWidget = (props: IPixiEnvProps) => {
   const [envs, setEnvs] = useState(['']);
+  const [defaultEnv, setDefaultEnv] = useState('');
 
   useEffect(() => {
     const fetchEnvironments = async () => {
@@ -25,12 +31,17 @@ export const PixiEnvWidget = (props: IPixiEnvProps) => {
           props.app.serviceManager.contents.localPath(relativePath);
         const serverRoot = PageConfig.getOption('serverRoot') || '';
 
-        const environments = await requestAPI<string[]>('envs', {
+        const response = await requestAPI<IEnvironmentResponse>('envs', {
           method: 'POST',
           body: JSON.stringify({ localPath, serverRoot })
         });
 
-        setEnvs(environments);
+        setEnvs(response.environments);
+        setDefaultEnv(response.default);
+
+        if (!props.value && response.default) {
+          props.onChange(response.default);
+        }
       } catch (error) {
         console.error('Failed to fetch environments:', error);
         setEnvs(['']);
@@ -44,7 +55,7 @@ export const PixiEnvWidget = (props: IPixiEnvProps) => {
     <select
       id={props.id}
       className="form-control"
-      value={props.value || ''}
+      value={props.value || defaultEnv}
       onChange={e => props.onChange(e.target.value)}
       required={props.required}
     >