Kubernetes support

* Total CPU and Memory usage for the entire cluster
* Total CPU and Memory usage for kubernetes pods
* Service discovery via annotations on ingress
* No storage stats yet
* No network stats yet

src/pages/api/widgets/kubernetes.js

@@ -0,0 +1,72 @@
+import { CoreV1Api, Metrics } from "@kubernetes/client-node";
+
+import getKubeConfig from "../../../utils/config/kubernetes";
+import { parseCpu, parseMemory } from "../../../utils/kubernetes/kubernetes-utils";
+
+export default async function handler(req, res) {
+  const { type } = req.query;
+
+  const kc = getKubeConfig();
+  const coreApi = kc.makeApiClient(CoreV1Api);
+  const metricsApi = new Metrics(kc);
+
+  const nodes = await coreApi.listNode();
+  const nodeCapacity = new Map();
+  let cpuTotal = 0;
+  let cpuUsage = 0;
+  let memTotal = 0;
+  let memUsage = 0;
+
+  nodes.body.items.forEach((node) => {
+    nodeCapacity.set(node.metadata.name, node.status.capacity);
+    cpuTotal += Number.parseInt(node.status.capacity.cpu, 10);
+    memTotal += parseMemory(node.status.capacity.memory);
+  });
+
+  const nodeMetrics = await metricsApi.getNodeMetrics();
+  const nodeUsage = new Map();
+  nodeMetrics.items.forEach((metrics) => {
+    nodeUsage.set(metrics.metadata.name, metrics.usage);
+    cpuUsage += parseCpu(metrics.usage.cpu);
+    memUsage += parseMemory(metrics.usage.memory);
+  });
+
+  if (type === "cpu") {
+    return res.status(200).json({
+      cpu: {
+        usage: (cpuUsage / cpuTotal) * 100,
+        load: cpuUsage
+      }
+    });
+  }
+  // Maybe Storage CSI can provide this information
+  // if (type === "disk") {
+  //   if (!existsSync(target)) {
+  //     return res.status(404).json({
+  //       error: "Target not found",
+  //     });
+  //   }
+  //
+  //   return res.status(200).json({
+  //     drive: await drive.info(target || "/"),
+  //   });
+  // }
+  //
+  if (type === "memory") {
+    const SCALE_MB = 1024 * 1024;
+    const usedMemMb = memUsage / SCALE_MB;
+    const totalMemMb = memTotal / SCALE_MB;
+    const freeMemMb = totalMemMb - usedMemMb;
+    return res.status(200).json({
+      memory: {
+        usedMemMb,
+        freeMemMb,
+        totalMemMb
+      }
+    });
+  }
+
+  return res.status(400).json({
+    error: "invalid type"
+  });
+}