Lens app source code (#119)

Signed-off-by: Jari Kolehmainen <jari.kolehmainen@gmail.com>

dashboard/server/routes/metrics-route.ts

@@ -0,0 +1,82 @@
+//-- Metrics
+// https://prometheus.io/docs/prometheus/latest/querying/api/
+
+import { Router } from "express";
+import config from "../config";
+import { kubeRequest } from "../api/kube-request";
+import { userSession } from "../user-session";
+import { AxiosError } from "axios";
+import { IMetrics } from "../../client/api/endpoints/metrics.api";
+import { IMetricsQuery } from "../common/metrics"
+
+
+export function metricsRoute() {
+  const router = Router();
+
+  router.post("/metrics", async (req, res, next) => {
+    const { authHeader } = userSession.get(req);
+    const { namespace, ...queryParams } = req.query;
+    const query: IMetricsQuery = req.body;
+
+    /*eslint-disable */
+    // add default namespace for rbac-proxy validation
+    if (!queryParams.kubernetes_namespace) {
+      queryParams.kubernetes_namespace = config.STATS_NAMESPACE;
+    }
+    /*eslint-enble */
+
+    // prometheus metrics loader
+    const attempts: { [query: string]: number } = {};
+    const maxAttempts = 5;
+    const loadMetrics = (query: string): Promise<IMetrics> => {
+      const attempt = attempts[query] = (attempts[query] || 0) + 1;
+      return kubeRequest<IMetrics>({
+        url: config.KUBE_METRICS_URL,
+        path: "/api/v1/query_range",
+        authHeader: authHeader,
+        params: {
+          query: query,
+          ...queryParams,
+        },
+      }).catch(async (err: AxiosError) => {
+        // https://github.com/axios/axios#handling-errors
+        if (!err.response && attempt < maxAttempts) {
+          await new Promise(resolve => setTimeout(resolve, attempt * 1000)); // add delay before repeating request
+          return loadMetrics(query);
+        }
+        return {
+          status: err.toString(),
+          data: {
+            result: []
+          },
+        } as IMetrics;
+      })
+    };
+
+    // return data in same structure as query
+    let data: any;
+    try {
+      if (typeof query === "string") {
+        data = await loadMetrics(query)
+      }
+      else if (Array.isArray(query)) {
+        data = await Promise.all(query.map(loadMetrics));
+      }
+      else {
+        data = {};
+        const result = await Promise.all(
+          Object.values(query).map(loadMetrics)
+        );
+        Object.keys(query).forEach((metricName, index) => {
+          data[metricName] = result[index];
+        });
+      }
+
+      res.json(data);
+    } catch (err) {
+      next(err);
+    }
+  });
+
+  return router;
+}