Simplify handleLensRequest by factoring out sub functions

Signed-off-by: Sebastian Malton <sebastian@malton.name>

src/common/utils/box.ts

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) OpenLens Authors. All rights reserved.
+ * Licensed under MIT License. See LICENSE in root directory for more information.
+ */
+
+export class Box<T> {
+  constructor(private value: T) {}
+
+  get = () => this.value;
+
+  set = (newValue: T) => {
+    this.value = newValue;
+  };
+}

src/main/lens-proxy/handle-lens-request.injectable.ts

@@ -5,14 +5,19 @@
 import { getInjectable } from "@ogre-tools/injectable";
 import assert from "assert";
 import type { IncomingMessage, ServerResponse } from "http";
+import type { ErrorCallback, ProxyResCallback } from "http-proxy";
 import HttpProxyServer from "http-proxy";
 import { Socket } from "net";
+import type { Logger } from "../../common/logger";
 import loggerInjectable from "../../common/logger.injectable";
+import { Box } from "../../common/utils/box";
 import { apiKubePrefix } from "../../common/vars";
 import contentSecurityPolicyInjectable from "../../common/vars/content-security-policy.injectable";
 import type { ClusterContextHandler } from "../context-handler/context-handler";
+import type { RouteRequest } from "../router/route-request.injectable";
 import routeRequestInjectable from "../router/route-request.injectable";
 import { getBoolean } from "../utils/parse-query";
+import type { GetClusterForRequest } from "./get-cluster-for-request.injectable";
 import getClusterForRequestInjectable from "./get-cluster-for-request.injectable";
 
 const getRequestId = (req: IncomingMessage) => {
@@ -37,6 +42,111 @@ export interface HandleLensRequest {
   stopHandling: () => void;
 }
 
+const getProxyTarget = async (req: IncomingMessage, contextHandler: ClusterContextHandler) => {
+  if (req.url?.startsWith(apiKubePrefix)) {
+    delete req.headers.authorization;
+    req.url = req.url.replace(apiKubePrefix, "");
+
+    return contextHandler.getApiTarget(isLongRunningRequest(req.url));
+  }
+
+  return undefined;
+};
+
+const onProxyResWith = (retryCounters: Map<string, number>): ProxyResCallback => (proxyRes, req, res) => {
+  retryCounters.delete(getRequestId(req));
+
+  proxyRes.on("aborted", () => { // happens when proxy target aborts connection
+    res.end();
+  });
+};
+
+interface OnErrorWithDeps {
+  closed: Box<boolean>;
+  logger: Logger;
+  retryCounters: Map<string, number>;
+  handleRequest: HandleRequest;
+}
+
+const onErrorWith = (deps: OnErrorWithDeps): ErrorCallback => {
+  const {
+    closed,
+    logger,
+    retryCounters,
+    handleRequest,
+  } = deps;
+
+  return (error, req, res, target) => {
+    if (closed.get() || res instanceof Socket) {
+      return;
+    }
+
+    logger.error(`[LENS-PROXY]: http proxy errored for cluster: ${error}`, { url: req.url });
+
+    if (target) {
+      logger.debug(`Failed proxy to target: ${JSON.stringify(target, null, 2)}`);
+
+      if (req.method === "GET" && (!res.statusCode || res.statusCode >= 500)) {
+        const reqId = getRequestId(req);
+        const retryCount = retryCounters.get(reqId) || 0;
+        const timeoutMs = retryCount * 250;
+
+        if (retryCount < 20) {
+          logger.debug(`Retrying proxy request to url: ${reqId}`);
+          setTimeout(() => {
+            retryCounters.set(reqId, retryCount + 1);
+
+            (async () => {
+              try {
+                await handleRequest(req, res);
+              } catch (error) {
+                logger.error(`[LENS-PROXY]: failed to handle request on proxy error: ${error}`);
+              }
+            })();
+          }, timeoutMs);
+        }
+      }
+    }
+
+    try {
+      res.writeHead(500).end(`Oops, something went wrong.\n${error}`);
+    } catch (e) {
+      logger.error(`[LENS-PROXY]: Failed to write headers: `, e);
+    }
+  };
+};
+
+interface HandleRequestWithDeps {
+  getClusterForRequest: GetClusterForRequest;
+  proxy: HttpProxyServer;
+  contentSecurityPolicy: string;
+  routeRequest: RouteRequest;
+}
+
+const handleRequestWith = (deps: HandleRequestWithDeps): HandleRequest => {
+  const {
+    getClusterForRequest,
+    proxy,
+    contentSecurityPolicy,
+    routeRequest,
+  } = deps;
+
+  return async (req, res) => {
+    const cluster = getClusterForRequest(req);
+
+    if (cluster) {
+      const proxyTarget = await getProxyTarget(req, cluster.contextHandler);
+
+      if (proxyTarget) {
+        return proxy.web(req, res, proxyTarget);
+      }
+    }
+
+    res.setHeader("Content-Security-Policy", contentSecurityPolicy);
+    await routeRequest(cluster, req, res);
+  };
+};
+
 const handleLensRequestInjectable = getInjectable({
   id: "handle-lens-request",
   instantiate: (di): HandleLensRequest => {
@@ -46,84 +156,27 @@ const handleLensRequestInjectable = getInjectable({
     const routeRequest = di.inject(routeRequestInjectable);
 
     const retryCounters = new Map<string, number>();
-    let closed = false;
+    const closed = new Box(false);
 
-    const getProxyTarget = async (req: IncomingMessage, contextHandler: ClusterContextHandler) => {
+    const proxy = HttpProxyServer.createProxy();
-      if (req.url?.startsWith(apiKubePrefix)) {
+    const handleRequest = handleRequestWith({
-        delete req.headers.authorization;
+      contentSecurityPolicy,
-        req.url = req.url.replace(apiKubePrefix, "");
+      getClusterForRequest,
+      proxy,
+      routeRequest,
+    });
 
-        return contextHandler.getApiTarget(isLongRunningRequest(req.url));
+    proxy.on("proxyRes", onProxyResWith(retryCounters));
-      }
+    proxy.on("error", onErrorWith({
-
+      closed,
-      return undefined;
+      handleRequest,
-    };
+      logger,
-
+      retryCounters,
-    const proxy = HttpProxyServer.createProxy()
+    }));
-      .on("proxyRes", (proxyRes, req, res) => {
-        retryCounters.delete(getRequestId(req));
-
-        proxyRes.on("aborted", () => { // happens when proxy target aborts connection
-          res.end();
-        });
-      })
-      .on("error", (error, req, res, target) => {
-        if (closed || res instanceof Socket) {
-          return;
-        }
-
-        logger.error(`[LENS-PROXY]: http proxy errored for cluster: ${error}`, { url: req.url });
-
-        if (target) {
-          logger.debug(`Failed proxy to target: ${JSON.stringify(target, null, 2)}`);
-
-          if (req.method === "GET" && (!res.statusCode || res.statusCode >= 500)) {
-            const reqId = getRequestId(req);
-            const retryCount = retryCounters.get(reqId) || 0;
-            const timeoutMs = retryCount * 250;
-
-            if (retryCount < 20) {
-              logger.debug(`Retrying proxy request to url: ${reqId}`);
-              setTimeout(() => {
-                retryCounters.set(reqId, retryCount + 1);
-
-                (async () => {
-                  try {
-                    await handleRequest(req, res);
-                  } catch (error) {
-                    logger.error(`[LENS-PROXY]: failed to handle request on proxy error: ${error}`);
-                  }
-                })();
-              }, timeoutMs);
-            }
-          }
-        }
-
-        try {
-          res.writeHead(500).end(`Oops, something went wrong.\n${error}`);
-        } catch (e) {
-          logger.error(`[LENS-PROXY]: Failed to write headers: `, e);
-        }
-      });
-
-    const handleRequest: HandleRequest = async (req, res) => {
-      const cluster = getClusterForRequest(req);
-
-      if (cluster) {
-        const proxyTarget = await getProxyTarget(req, cluster.contextHandler);
-
-        if (proxyTarget) {
-          return proxy.web(req, res, proxyTarget);
-        }
-      }
-
-      res.setHeader("Content-Security-Policy", contentSecurityPolicy);
-      await routeRequest(cluster, req, res);
-    };
 
     return {
       handle: handleRequest,
-      stopHandling: () => closed = true,
+      stopHandling: () => closed.set(true),
     };
   },
 });