fix some issuen, added cache and added a test for the config

app/cache.py

@@ -0,0 +1,71 @@
+import streamlit as st
+from app import cfg
+from app.k8s_client import get_core, get_custom_client, fetch_nodes, fetch_pods
+
+
+@st.cache_resource
+def clients():
+    get_core()
+    get_custom_client()
+
+
+@st.cache_data(ttl=cfg.cache_ttl)
+def cached_nodes():
+    return fetch_nodes()
+
+
+@st.cache_data(ttl=cfg.cache_ttl)
+def cached_pods(namespace="all"):
+    return fetch_pods(namespace=namespace)
+
+
+@st.cache_data(ttl=cfg.cache_ttl)
+def cached_deployments(namespace="all"):
+    from kubernetes import client as _k8s
+    get_core()  # ensures kubeconfig is loaded before AppsV1Api is created
+    apps_v1 = _k8s.AppsV1Api()
+    if namespace == "all":
+        items = apps_v1.list_deployment_for_all_namespaces().items
+    else:
+        items = apps_v1.list_namespaced_deployment(namespace=namespace).items
+    return [
+        {
+            "namespace": d.metadata.namespace,
+            "name": d.metadata.name,
+            "ready": f"{d.status.ready_replicas or 0}/{d.spec.replicas or 0}",
+            "available": d.status.available_replicas or 0,
+            "desired": d.spec.replicas or 0,
+        }
+        for d in items
+    ]
+
+
+@st.cache_data(ttl=cfg.cache_ttl)
+def cached_namespaces():
+    return [ns.metadata.name for ns in get_core().list_namespace().items]
+
+
+@st.cache_data(ttl=cfg.cache_ttl)
+def cached_node_metrics():
+    try:
+        api = get_custom_client()
+        data = api.list_cluster_custom_object(
+            group="metrics.k8s.io", version="v1beta1", plural="nodes"
+        )
+        return {
+            item["metadata"]["name"]: {
+                "cpu_usage": item["usage"]["cpu"],
+                "memory_usage": item["usage"]["memory"],
+            }
+            for item in data["items"]
+        }
+    except Exception:
+        return {}
+
+
+def clear():
+    cached_nodes.clear()
+    cached_pods.clear()
+    cached_deployments.clear()
+    cached_namespaces.clear()
+    cached_node_metrics.clear()