240 lines
10 KiB
Markdown
240 lines
10 KiB
Markdown
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# global-agent
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[](https://gitspo.com/mentions/gajus/global-agent)
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[](https://travis-ci.org/gajus/global-agent)
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[](https://coveralls.io/github/gajus/global-agent)
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[](https://www.npmjs.org/package/global-agent)
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[](https://github.com/gajus/canonical)
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[](https://twitter.com/kuizinas)
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Global HTTP/HTTPS proxy configurable using environment variables.
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* [Usage](#usage)
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* [Setup proxy using `global-agent/bootstrap`](#setup-proxy-using-global-agentbootstrap)
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* [Setup proxy using `bootstrap` routine](#setup-proxy-using-bootstrap-routine)
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* [Runtime configuration](#runtime-configuration)
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* [Exclude URLs](#exclude-urls)
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* [Enable logging](#enable-logging)
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* [API](#api)
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* [`createGlobalProxyAgent`](#createglobalproxyagent)
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* [Environment variables](#environment-variables)
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* [`global.GLOBAL_AGENT`](#globalglobal_agent)
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* [Supported libraries](#supported-libraries)
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* [FAQ](#faq)
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* [What is the reason `global-agent` overrides explicitly configured HTTP(S) agent?](#what-is-the-reason-global-agent-overrides-explicitly-configured-https-agent)
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* [What is the reason `global-agent/bootstrap` does not use `HTTP_PROXY`?](#what-is-the-reason-global-agentbootstrap-does-not-use-http_proxy)
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* [What is the difference from `global-tunnel` and `tunnel`?](#what-is-the-difference-from-global-tunnel-and-tunnel)
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## Usage
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### Setup proxy using `global-agent/bootstrap`
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To configure HTTP proxy:
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1. Import `global-agent/bootstrap`.
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1. Export HTTP proxy address as `GLOBAL_AGENT_HTTP_PROXY` environment variable.
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Code:
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```js
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import 'global-agent/bootstrap';
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// or:
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// import {bootstrap} from 'global-agent';
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// bootstrap();
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```
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Bash:
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```bash
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$ export GLOBAL_AGENT_HTTP_PROXY=http://127.0.0.1:8080
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```
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Alternatively, you can preload module using Node.js `--require, -r` configuration, e.g.
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```bash
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$ export GLOBAL_AGENT_HTTP_PROXY=http://127.0.0.1:8080
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$ node -r 'global-agent/bootstrap' your-script.js
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```
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### Setup proxy using `bootstrap` routine
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Instead of importing a self-initialising script with side-effects as demonstrated in the [setup proxy using `global-agent/bootstrap`](#setup-proxy-using-global-agentbootstrap) documentation, you can import `bootstrap` routine and explicitly evaluate the bootstrap logic, e.g.
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```js
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import {
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bootstrap
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} from 'global-agent';
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bootstrap();
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```
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This is useful if you need to conditionally bootstrap `global-agent`, e.g.
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```js
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import {
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bootstrap
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} from 'global-agent';
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import globalTunnel from 'global-tunnel-ng';
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const MAJOR_NODEJS_VERSION = parseInt(process.version.slice(1).split('.')[0], 10);
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if (MAJOR_NODEJS_VERSION >= 10) {
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// `global-agent` works with Node.js v10 and above.
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bootstrap();
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} else {
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// `global-tunnel-ng` works only with Node.js v10 and below.
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globalTunnel.initialize();
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}
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```
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### Setup proxy using `createGlobalProxyAgent`
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If you do not want to use `global.GLOBAL_AGENT` variable, then you can use `createGlobalProxyAgent` to instantiate a controlled instance of `global-agent`, e.g.
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```js
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import {
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createGlobalProxyAgent
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} from 'global-agent';
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const globalProxyAgent = createGlobalProxyAgent();
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```
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Unlike `bootstrap` routine, `createGlobalProxyAgent` factory does not create `global.GLOBAL_AGENT` variable and does not guard against multiple initializations of `global-agent`. The result object of `createGlobalProxyAgent` is equivalent to `global.GLOBAL_AGENT`.
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### Runtime configuration
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`global-agent/bootstrap` script copies `process.env.GLOBAL_AGENT_HTTP_PROXY` value to `global.GLOBAL_AGENT.HTTP_PROXY` and continues to use the latter variable.
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You can override the `global.GLOBAL_AGENT.HTTP_PROXY` value at runtime to change proxy behaviour, e.g.
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```js
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http.get('http://127.0.0.1:8000');
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global.GLOBAL_AGENT.HTTP_PROXY = 'http://127.0.0.1:8001';
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http.get('http://127.0.0.1:8000');
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global.GLOBAL_AGENT.HTTP_PROXY = 'http://127.0.0.1:8002';
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```
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The first HTTP request is going to use http://127.0.0.1:8001 proxy and the secord request is going to use http://127.0.0.1:8002.
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All `global-agent` configuration is available under `global.GLOBAL_AGENT` namespace.
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### Exclude URLs
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The `GLOBAL_AGENT_NO_PROXY` environment variable specifies a pattern of URLs that should be excluded from proxying. `GLOBAL_AGENT_NO_PROXY` value is a comma-separated list of domain names. Asterisks can be used as wildcards, e.g.
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```bash
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export GLOBAL_AGENT_NO_PROXY='*.foo.com,baz.com'
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```
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says to contact all machines with the 'foo.com' TLD and 'baz.com' domains directly.
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### Separate proxy for HTTPS
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The environment variable `GLOBAL_AGENT_HTTPS_PROXY` can be set to specify a separate proxy for HTTPS requests. When this variable is not set `GLOBAL_AGENT_HTTP_PROXY` is used for both HTTP and HTTPS requests.
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### Enable logging
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`global-agent` is using [`roarr`](https://www.npmjs.com/package/roarr) logger to log HTTP requests and response (HTTP status code and headers), e.g.
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```json
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{"context":{"program":"global-agent","namespace":"Agent","logLevel":10,"destination":"http://gajus.com","proxy":"http://127.0.0.1:8076"},"message":"proxying request","sequence":1,"time":1556269669663,"version":"1.0.0"}
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{"context":{"program":"global-agent","namespace":"Agent","logLevel":10,"headers":{"content-type":"text/plain","content-length":"2","date":"Fri, 26 Apr 2019 12:07:50 GMT","connection":"close"},"requestId":6,"statusCode":200},"message":"proxying response","sequence":2,"time":1557133856955,"version":"1.0.0"}
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```
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Export `ROARR_LOG=true` environment variable to enable log printing to stdout.
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Use [`roarr-cli`](https://github.com/gajus/roarr-cli) program to pretty-print the logs.
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## API
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### `createGlobalProxyAgent`
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```js
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/**
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* @property environmentVariableNamespace Defines namespace of `HTTP_PROXY`, `HTTPS_PROXY` and `NO_PROXY` environment variables. (Default: `GLOBAL_AGENT_`)
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* @property forceGlobalAgent Forces to use `global-agent` HTTP(S) agent even when request was explicitly constructed with another agent. (Default: `true`)
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* @property socketConnectionTimeout Destroys socket if connection is not established within the timeout. (Default: `60000`)
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*/
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type ProxyAgentConfigurationInputType = {|
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+environmentVariableNamespace?: string,
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+forceGlobalAgent?: boolean,
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+socketConnectionTimeout?: number,
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(configurationInput: ProxyAgentConfigurationInputType) => ProxyAgentConfigurationType;
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```
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### Environment variables
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|Name|Description|Default|
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|`GLOBAL_AGENT_ENVIRONMENT_VARIABLE_NAMESPACE`|Defines namespace of `HTTP_PROXY`, `HTTPS_PROXY` and `NO_PROXY` environment variables.|`GLOBAL_AGENT_`|
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|`GLOBAL_AGENT_FORCE_GLOBAL_AGENT`|Forces to use `global-agent` HTTP(S) agent even when request was explicitly constructed with another agent.|`true`|
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|`GLOBAL_AGENT_SOCKET_CONNECTION_TIMEOUT`|Destroys socket if connection is not established within the timeout.|`60000`|
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|`${NAMESPACE}_HTTP_PROXY`|Sets the initial proxy controller HTTP_PROXY value.|N/A|
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|`${NAMESPACE}_HTTPS_PROXY`|Sets the initial proxy controller HTTPS_PROXY value.|N/A|
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|`${NAMESPACE}_NO_PROXY`|Sets the initial proxy controller NO_PROXY value.|N/A|
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### `global.GLOBAL_AGENT`
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`global.GLOBAL_AGENT` is initialized by `bootstrap` routine.
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`global.GLOBAL_AGENT` has the following properties:
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|Name|Description|Configurable|
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|`HTTP_PROXY`|Yes|Sets HTTP proxy to use.|
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|`HTTPS_PROXY`|Yes|Sets a distinct proxy to use for HTTPS requests.|
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|`NO_PROXY`|Yes|Specifies a pattern of URLs that should be excluded from proxying. See [Exclude URLs](#exclude-urls).|
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## Supported libraries
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`global-agent` works with all libraries that internally use [`http.request`](https://nodejs.org/api/http.html#http_http_request_options_callback).
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`global-agent` has been tested to work with:
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* [`got`](https://www.npmjs.com/package/got)
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* [`axios`](https://www.npmjs.com/package/axios)
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* [`request`](https://www.npmjs.com/package/axios)
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## FAQ
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### What is the reason `global-agent` overrides explicitly configured HTTP(S) agent?
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By default, `global-agent` overrides [`agent` property](https://nodejs.org/api/http.html#http_http_request_options_callback) of any HTTP request, even if `agent` property was explicitly set when constructing a HTTP request. This behaviour allows to intercept requests of libraries that use a custom instance of an agent per default (e.g. Stripe SDK [uses an `http(s).globalAgent` instance pre-configured with `keepAlive: true`](https://github.com/stripe/stripe-node/blob/e542902dd8fbe591fe3c3ce07a7e89d1d60e4cf7/lib/StripeResource.js#L11-L12)).
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This behaviour can be disabled with `GLOBAL_AGENT_FORCE_GLOBAL_AGENT=false` environment variable. When disabled, then `global-agent` will only set `agent` property when it is not already defined or if `agent` is an instance of `http(s).globalAgent`.
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### What is the reason `global-agent/bootstrap` does not use `HTTP_PROXY`?
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Some libraries (e.g. [`request`](https://npmjs.org/package/request)) change their behaviour when `HTTP_PROXY` environment variable is present. Using a namespaced environment variable prevents conflicting library behaviour.
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You can override this behaviour by configuring `GLOBAL_AGENT_ENVIRONMENT_VARIABLE_NAMESPACE` variable, e.g.
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```bash
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$ export GLOBAL_AGENT_ENVIRONMENT_VARIABLE_NAMESPACE=
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```
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Now script initialized using `global-agent/bootstrap` will use `HTTP_PROXY`, `HTTPS_PROXY` and `NO_PROXY` environment variables.
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### What is the difference from `global-tunnel` and `tunnel`?
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[`global-tunnel`](https://github.com/salesforce/global-tunnel) (including [`global-tunnel-ng`](https://github.com/np-maintain/global-tunnel) and [`tunnel`](https://npmjs.com/package/tunnel)) are designed to support legacy Node.js versions. They use various [workarounds](https://github.com/koichik/node-tunnel/blob/5fb2fb424788597146b7be6729006cad1cf9e9a8/lib/tunnel.js#L134-L144) and rely on [monkey-patching `http.request`, `http.get`, `https.request` and `https.get` methods](https://github.com/np-maintain/global-tunnel/blob/51413dcf0534252b5049ec213105c7063ccc6367/index.js#L302-L338).
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In contrast, `global-agent` supports Node.js v10 and above, and does not implements workarounds for the older Node.js versions.
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