feat(api): support pagination on list_apps route (#77)

spark_on_k8s/api/apps.py

@@ -1,6 +1,9 @@
 from __future__ import annotations
 
 from fastapi import APIRouter
+
+# ruff: noqa: TCH002
+from fastapi.responses import Response
 from kubernetes_asyncio.client import CoreV1Api
 from pydantic import BaseModel
 
@@ -24,25 +27,56 @@ class SparkApp(BaseModel):
     spark_history_proxy: bool = False
 
 
+async def _list_apps(namespace: str, max_per_page: int, continue_from: str) -> tuple[str, list[SparkApp]]:
+    no_more_items = "no-more-items"
+    if continue_from == no_more_items:
+        return no_more_items, []
+    core_client = CoreV1Api(await KubernetesClientSingleton.client())
+    search_params = {
+        "namespace": namespace,
+        "label_selector": "spark-role=driver",
+        "limit": max_per_page,
+    }
+    if continue_from:
+        search_params["_continue"] = continue_from
+    driver_pods = await core_client.list_namespaced_pod(**search_params)
+    return (
+        driver_pods.metadata._continue if driver_pods.metadata._continue else no_more_items,
+        [
+            SparkApp(
+                app_id=pod.metadata.labels.get("spark-app-id", pod.metadata.name),
+                status=get_app_status(pod),
+                driver_logs=True,
+                spark_ui_proxy=pod.metadata.labels.get("spark-ui-proxy", False),
+            )
+            for pod in driver_pods.items
+        ],
+    )
+
+
 @router.get("/list_apps")
-async def list_apps_default_namespace() -> list[SparkApp]:
+async def list_apps_default_namespace(
+    response: Response, max_per_page: int = 10, continue_from: str = ""
+) -> list[SparkApp]:
     """List spark apps in the default namespace."""
-    return await list_apps(namespace=APIConfiguration.SPARK_ON_K8S_API_DEFAULT_NAMESPACE)
+    continue_from, apps = await _list_apps(
+        namespace=APIConfiguration.SPARK_ON_K8S_API_DEFAULT_NAMESPACE,
+        max_per_page=max_per_page,
+        continue_from=continue_from,
+    )
+    response.headers["X-Continue"] = continue_from
+    return apps
 
 
 @router.get("/list_apps/{namespace}")
-async def list_apps(namespace: str) -> list[SparkApp]:
+async def list_apps(
+    response: Response, namespace: str, max_per_page: int = 10, continue_from: str = ""
+) -> list[SparkApp]:
     """List spark apps in a namespace."""
-    core_client = CoreV1Api(await KubernetesClientSingleton.client())
-    driver_pods = await core_client.list_namespaced_pod(
-        namespace=namespace, label_selector="spark-role=driver"
+    continue_from, apps = await _list_apps(
+        namespace=namespace,
+        max_per_page=max_per_page,
+        continue_from=continue_from,
     )
-    return [
-        SparkApp(
-            app_id=pod.metadata.labels.get("spark-app-id", pod.metadata.name),
-            status=get_app_status(pod),
-            driver_logs=True,
-            spark_ui_proxy=pod.metadata.labels.get("spark-ui-proxy", False),
-        )
-        for pod in driver_pods.items
-    ]
+    response.headers["X-Continue"] = continue_from
+    return apps