Implement automatic cloud proxying

Author: nhooyr

package.json

@@ -82,7 +82,8 @@
     "tar-fs": "^2.0.0",
     "ws": "^7.2.0",
     "xdg-basedir": "^4.0.0",
-    "yarn": "^1.22.4"
+    "yarn": "^1.22.4",
+    "delay": "^4.4.0"
   },
   "bin": {
     "code-server": "out/node/entry.js"

src/node/coder-cloud.ts

@@ -2,9 +2,14 @@ import { spawn } from "child_process"
 import path from "path"
 import { logger } from "@coder/logger"
 import split2 from "split2"
+import delay from "delay"
+import fs from "fs"
+import { promisify } from "util"
+import xdgBasedir from "xdg-basedir"
+
+const coderCloudAgent = path.resolve(__dirname, "../../lib/coder-cloud-agent")
 
 export async function coderCloudExpose(serverName: string): Promise<void> {
-  const coderCloudAgent = path.resolve(__dirname, "../../lib/coder-cloud-agent")
   const agent = spawn(coderCloudAgent, ["link", serverName], {
     stdio: ["inherit", "inherit", "pipe"],
   })
@@ -28,3 +33,125 @@ export async function coderCloudExpose(serverName: string): Promise<void> {
     })
   })
 }
+
+export function coderCloudProxy(addr: string) {
+  // addr needs to be in host:port format.
+  // So we trim the protocol.
+  addr = addr.replace(/^https?:\/\//, "")
+
+  if (!xdgBasedir.config) {
+    return
+  }
+
+  const sessionTokenPath = path.join(xdgBasedir.config, "coder-cloud", "session")
+
+  const _proxy = async () => {
+    await waitForPath(sessionTokenPath)
+
+    logger.info("exposing coder-server with coder-cloud")
+
+    const agent = spawn(coderCloudAgent, ["proxy", "--code-server-addr", addr], {
+      stdio: ["inherit", "inherit", "pipe"],
+    })
+
+    agent.stderr.pipe(split2()).on("data", line => {
+      line = line.replace(/^[0-9-]+ [0-9:]+ [^ ]+\t/, "")
+      logger.info(line)
+    })
+
+    return new Promise((res, rej) => {
+      agent.on("error", rej)
+
+      agent.on("close", code => {
+        if (code !== 0) {
+          rej({
+            message: `coder cloud agent exited with ${code}`,
+          })
+          return
+        }
+        res()
+      })
+    })
+  }
+
+  const proxy = async () => {
+    try {
+      await _proxy()
+    } catch(err) {
+      logger.error(err.message)
+    }
+    setTimeout(proxy, 3000)
+  }
+  proxy()
+}
+
+/**
+ * waitForPath efficiently implements waiting for the existence of a path.
+ *
+ * We intentionally do not use fs.watchFile as it is very slow from testing.
+ * I believe it polls instead of watching.
+ *
+ * The way this works is for each level of the path it will check if it exists
+ * and if not, it will wait for it. e.g. if the path is /home/nhooyr/.config/coder-cloud/session
+ * then first it will check if /home exists, then /home/nhooyr and so on.
+ *
+ * The wait works by first creating a watch promise for the p segment.
+ * We call fs.watch on the dirname of the p segment. When the dirname has a change,
+ * we check if the p segment exists and if it does, we resolve the watch promise.
+ * On any error or the watcher being closed, we reject the watch promise.
+ *
+ * Once that promise is setup, we check if the p segment exists with fs.exists
+ * and if it does, we close the watcher and return.
+ *
+ * Now we race the watch promise and a 2000ms delay promise. Once the race
+ * is complete, we close the watcher.
+ *
+ * If the watch promise was the one to resolve, we return.
+ * Otherwise we setup the watch promise again and retry.
+ *
+ * This combination of polling and watching is very reliable and efficient.
+ */
+async function waitForPath(p: string): Promise<void> {
+  const segs = p.split(path.sep)
+  for (let i = 0; i < segs.length; i++) {
+    const s = path.join("/", ...segs.slice(0, i + 1))
+    // We need to wait for each segment to exist.
+    await _waitForPath(s)
+  }
+}
+
+async function _waitForPath(p: string): Promise<void> {
+  const watchDir = path.dirname(p)
+
+  logger.debug(`waiting for ${p}`)
+
+  for (;;) {
+    const w = fs.watch(watchDir)
+    const watchPromise = new Promise<void>((res, rej) => {
+      w.on("change", async () => {
+        if (await promisify(fs.exists)(p)) {
+          res()
+        }
+      })
+      w.on("close", () => rej(new Error("watcher closed")))
+      w.on("error", rej)
+    })
+
+    // We want to ignore any errors from this promise being rejected if the file
+    // already exists below.
+    watchPromise.catch(() => {})
+
+    if (await promisify(fs.exists)(p)) {
+      // The path exists!
+      w.close()
+      return
+    }
+
+    // Now we wait for either the watch promise to resolve/reject or 2000ms.
+    const s = await Promise.race([watchPromise.then(() => "exists"), delay(2000)])
+    w.close()
+    if (s === "exists") {
+      return
+    }
+  }
+}

src/node/entry.ts

@@ -12,11 +12,11 @@ import { StaticHttpProvider } from "./app/static"
 import { UpdateHttpProvider } from "./app/update"
 import { VscodeHttpProvider } from "./app/vscode"
 import { Args, bindAddrFromAllSources, optionDescriptions, parse, readConfigFile, setDefaults } from "./cli"
+import { coderCloudExpose, coderCloudProxy } from "./coder-cloud"
 import { AuthType, HttpServer, HttpServerOptions } from "./http"
 import { loadPlugins } from "./plugin"
 import { generateCertificate, hash, humanPath, open } from "./util"
 import { ipcMain, wrap } from "./wrapper"
-import { coderCloudExpose } from "./coder-cloud"
 
 process.on("uncaughtException", (error) => {
   logger.error(`Uncaught exception: ${error.message}`)
@@ -123,6 +123,8 @@ const main = async (args: Args, cliArgs: Args, configArgs: Args): Promise<void>
     httpServer.proxyDomains.forEach((domain) => logger.info(`    - *.${domain}`))
   }
 
+  coderCloudProxy(serverAddress!)
+
   if (serverAddress && !options.socket && args.open) {
     // The web socket doesn't seem to work if browsing with 0.0.0.0.
     const openAddress = serverAddress.replace(/:\/\/0.0.0.0/, "://localhost")

yarn.lock

@@ -2525,6 +2525,11 @@ define-property@^2.0.2:
     is-descriptor "^1.0.2"
     isobject "^3.0.1"
 
+delay@^4.4.0:
+  version "4.4.0"
+  resolved "https://registry.yarnpkg.com/delay/-/delay-4.4.0.tgz#71abc745f3ce043fe7f450491236541edec4ad0c"
+  integrity sha512-txgOrJu3OdtOfTiEOT2e76dJVfG/1dz2NZ4F0Pyt4UGZJryssMRp5vdM5wQoLwSOBNdrJv3F9PAhp/heqd7vrA==
+
 delayed-stream@~1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/delayed-stream/-/delayed-stream-1.0.0.tgz#df3ae199acadfb7d440aaae0b29e2272b24ec619"