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[proxy-agent] Lazily load agents (#327)
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‎.changeset/late-berries-rule.md

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@@ -0,0 +1,5 @@
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---
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'proxy-agent': minor
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---
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Lazily load agents in proxy-agent

‎packages/proxy-agent/src/index.ts

+37-28
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@@ -5,47 +5,57 @@ import LRUCache from 'lru-cache';
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import { Agent, AgentConnectOpts } from 'agent-base';
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import createDebug from 'debug';
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import { getProxyForUrl as envGetProxyForUrl } from 'proxy-from-env';
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import { PacProxyAgent, PacProxyAgentOptions } from 'pac-proxy-agent';
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import { HttpProxyAgent, HttpProxyAgentOptions } from 'http-proxy-agent';
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import { HttpsProxyAgent, HttpsProxyAgentOptions } from 'https-proxy-agent';
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import { SocksProxyAgent, SocksProxyAgentOptions } from 'socks-proxy-agent';
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import type { PacProxyAgent, PacProxyAgentOptions } from 'pac-proxy-agent';
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import type { HttpProxyAgent, HttpProxyAgentOptions } from 'http-proxy-agent';
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import type { HttpsProxyAgent, HttpsProxyAgentOptions } from 'https-proxy-agent';
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import type { SocksProxyAgent, SocksProxyAgentOptions } from 'socks-proxy-agent';
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const debug = createDebug('proxy-agent');
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const PROTOCOLS = [
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...HttpProxyAgent.protocols,
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...SocksProxyAgent.protocols,
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...PacProxyAgent.protocols,
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] as const;
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type ValidProtocol =
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| (typeof HttpProxyAgent.protocols)[number]
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| (typeof HttpsProxyAgent.protocols)[number]
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| (typeof SocksProxyAgent.protocols)[number]
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| (typeof PacProxyAgent.protocols)[number];
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type ValidProtocol = (typeof PROTOCOLS)[number];
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type AgentConstructor = new (...args: never[]) => Agent;
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type AgentConstructor = new (proxy: string, proxyAgentOptions?: ProxyAgentOptions) => Agent;
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type GetProxyForUrlCallback = (url: string) => string | Promise<string>;
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/**
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* Shorthands for built-in supported types.
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* Lazily loaded since some of these imports can be quite expensive
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* (in particular, pac-proxy-agent).
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*/
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const wellKnownAgents = {
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http: async () => (await import('http-proxy-agent')).HttpProxyAgent,
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https: async () => (await import('https-proxy-agent')).HttpsProxyAgent,
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socks: async () => (await import('socks-proxy-agent')).SocksProxyAgent,
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pac: async () => (await import('pac-proxy-agent')).PacProxyAgent,
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} as const;
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/**
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* Supported proxy types.
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*/
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export const proxies: {
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[P in ValidProtocol]: [AgentConstructor, AgentConstructor];
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[P in ValidProtocol]: [() => Promise<AgentConstructor>, () => Promise<AgentConstructor>];
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} = {
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http: [HttpProxyAgent, HttpsProxyAgent],
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https: [HttpProxyAgent, HttpsProxyAgent],
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socks: [SocksProxyAgent, SocksProxyAgent],
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socks4: [SocksProxyAgent, SocksProxyAgent],
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socks4a: [SocksProxyAgent, SocksProxyAgent],
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socks5: [SocksProxyAgent, SocksProxyAgent],
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socks5h: [SocksProxyAgent, SocksProxyAgent],
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'pac+data': [PacProxyAgent, PacProxyAgent],
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'pac+file': [PacProxyAgent, PacProxyAgent],
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'pac+ftp': [PacProxyAgent, PacProxyAgent],
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'pac+http': [PacProxyAgent, PacProxyAgent],
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'pac+https': [PacProxyAgent, PacProxyAgent],
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http: [wellKnownAgents.http, wellKnownAgents.https],
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https: [wellKnownAgents.http, wellKnownAgents.https],
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socks: [wellKnownAgents.socks, wellKnownAgents.socks],
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socks4: [wellKnownAgents.socks, wellKnownAgents.socks],
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socks4a: [wellKnownAgents.socks, wellKnownAgents.socks],
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socks5: [wellKnownAgents.socks, wellKnownAgents.socks],
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socks5h: [wellKnownAgents.socks, wellKnownAgents.socks],
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'pac+data': [wellKnownAgents.pac, wellKnownAgents.pac],
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'pac+file': [wellKnownAgents.pac, wellKnownAgents.pac],
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'pac+ftp': [wellKnownAgents.pac, wellKnownAgents.pac],
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'pac+http': [wellKnownAgents.pac, wellKnownAgents.pac],
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'pac+https': [wellKnownAgents.pac, wellKnownAgents.pac],
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};
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function isValidProtocol(v: string): v is ValidProtocol {
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return (PROTOCOLS as readonly string[]).includes(v);
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return Object.keys(proxies).includes(v);
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}
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export type ProxyAgentOptions = HttpProxyAgentOptions<''> &
@@ -138,8 +148,7 @@ export class ProxyAgent extends Agent {
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throw new Error(`Unsupported protocol for proxy URL: ${proxy}`);
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}
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const ctor =
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proxies[proxyProto][secureEndpoint || isWebSocket ? 1 : 0];
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// @ts-expect-error meh…
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await proxies[proxyProto][secureEndpoint || isWebSocket ? 1 : 0]();
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agent = new ctor(proxy, this.connectOpts);
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this.cache.set(cacheKey, agent);
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} else {

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