proxy: per-URL env proxy via undici

Author: lroolle

bun.lock

@@ -45,8 +45,10 @@
     "fetch-event-stream": "^0.1.5",
     "gpt-tokenizer": "^3.0.1",
     "hono": "^4.9.4",
+    "proxy-from-env": "^1.1.0",
     "srvx": "^0.8.6",
-    "tiny-invariant": "^1.3.3"
+    "tiny-invariant": "^1.3.3",
+    "undici": "^6.19.8"
   },
   "devDependencies": {
     "@echristian/eslint-config": "^0.0.53",

package.json

@@ -0,0 +1,62 @@
+import consola from "consola"
+import { getProxyForUrl } from "proxy-from-env"
+import { Agent, ProxyAgent, setGlobalDispatcher, type Dispatcher } from "undici"
+
+export function initProxyFromEnv(): void {
+  if (typeof Bun !== "undefined") return
+
+  try {
+    const direct = new Agent()
+    const proxies = new Map<string, ProxyAgent>()
+
+    const dispatcher: Dispatcher = {
+      dispatch(
+        options: Dispatcher.RequestOptions,
+        handler: Dispatcher.DispatchHandlers,
+      ) {
+        try {
+          const origin =
+            typeof options.origin === "string" ?
+              new URL(options.origin)
+            : (options.origin as URL)
+          const get = getProxyForUrl as unknown as (
+            u: string,
+          ) => string | undefined
+          const raw = get(origin.toString())
+          const proxyUrl = raw && raw.length > 0 ? raw : undefined
+          if (!proxyUrl) {
+            consola.debug(`HTTP proxy bypass: ${origin.hostname}`)
+            return (direct as unknown as Dispatcher).dispatch(options, handler)
+          }
+          let agent = proxies.get(proxyUrl)
+          if (!agent) {
+            agent = new ProxyAgent(proxyUrl)
+            proxies.set(proxyUrl, agent)
+          }
+          let label = proxyUrl
+          try {
+            const u = new URL(proxyUrl)
+            label = `${u.protocol}//${u.host}`
+          } catch {
+            /* noop */
+          }
+          consola.debug(`HTTP proxy route: ${origin.hostname} via ${label}`)
+          return (agent as unknown as Dispatcher).dispatch(options, handler)
+        } catch {
+          return (direct as unknown as Dispatcher).dispatch(options, handler)
+        }
+      },
+      close() {
+        return direct.close()
+      },
+      destroy() {
+        return direct.destroy()
+      },
+    }
+
+    setGlobalDispatcher(dispatcher)
+    consola.debug("HTTP proxy configured from environment (per-URL)")
+  } catch (err) {
+    consola.debug("Proxy setup skipped:", err)
+  }
+}

src/lib/proxy.ts

@@ -5,6 +5,7 @@ import { defineCommand, runMain } from "citty"
 import { auth } from "./auth"
 import { checkUsage } from "./check-usage"
 import { debug } from "./debug"
+import { initProxyFromEnv } from "./lib/proxy"
 import { start } from "./start"
 
 const main = defineCommand({
@@ -16,4 +17,6 @@ const main = defineCommand({
   subCommands: { auth, start, "check-usage": checkUsage, debug },
 })
 
+initProxyFromEnv()
+
 await runMain(main)