---
# Mocks Server Plugin Proxy
Plugin for [Mocks Server][website-url] that provides a [variant handler](https://www.mocks-server.org/docs/variant-handlers/intro) that proxy requests to another host and pass response back to original caller.
It uses the [express-http-proxy](https://github.com/villadora/express-http-proxy) package under the hood, and supports all of its options.
> Important: From v3.0.0, this plugin includes two route handlers: `proxy` and `proxy-v4`. This was made to allow Mocks Server v3 users to progressively adapt their code to Mocks Server v4 without breaking changes. It is strongly recommended to use the `proxy-v4` handler. In the next major release, backward compatibilty will be removed and the `proxy` handler will be replaced by `proxy-v4`.
## Usage of `proxy-v4` handler
This plugin is included in the [main distribution of the Mocks Server project][main-distribution-url], so you can also read the [official documentation website][website-url].
### Proxy routes
If you want a [route variant](https://www.mocks-server.org/docs/usage/variants) to use the `proxy-v4` handler, define its `handler` property as "proxy-v4". Use the `host` property to set the host for the route, and the `options` property to set any of the [express-http-proxy](https://github.com/villadora/express-http-proxy) options.
```js
module.exports = [
{
id: "proxy-all",
url: "*",
method: ["GET", "POST", "PATCH", "PUT"],
variants: [
{
id: "proxy-to-google",
type: "proxy-v4", // This route variant will use the "proxy" handler from this plugin
options: {
host: "https://www.google.com", // proxy host
options: {}, // Options for express-http-proxy
},
},
],
},
];
```
### Options
Here are listed the specific properties that can be defined in a `proxy-v4` route variant. They must be defined in the `options` property of the variant:
* __`host`__ _(String|Function)_: The proxy host. Equivalent to the [`express-http-proxy` `host` option](https://github.com/villadora/express-http-proxy#host), so it can also be a function.
* __`options`__ _(Object)_: Object containing any of the [options supported by the `express-http-proxy` package](https://github.com/villadora/express-http-proxy#options). Some of them are:
* __filter__ _(Function)_: [`filter` option](https://github.com/villadora/express-http-proxy#filter-supports-promises) for `express-http-proxy`.
* __userResDecorator__ _(Function)_: [`userResDecorator` option](https://github.com/villadora/express-http-proxy#userresdecorator-was-intercept-supports-promise) for `express-http-proxy`.
* __...__ all other [`express-http-proxy` options](https://github.com/villadora/express-http-proxy#options) are also supported.
> Tip: Note that the variant `delay` option is still valid for routes handled by this plugin, so you can use it to simulate that host responses are slow.
## Usage of `proxy` handler
### Proxy routes
If you want a Mocks Server v3 [route variant](https://www.mocks-server.org/docs/usage/variants) to use the `proxy` handler, define its `type` property as "proxy". Use the `host` property to set the host for the route, and the `options` property to set any of the [express-http-proxy](https://github.com/villadora/express-http-proxy) options.
```js
module.exports = [
{
id: "proxy-all",
url: "*",
method: ["GET", "POST", "PATCH", "PUT"],
variants: [
{
id: "proxy-to-google",
type: "proxy", // This route variant will use the "proxy" handler from this plugin
host: "https://www.google.com", // proxy host
options: {}, // Options for express-http-proxy
},
],
},
];
```
### Route variant options
Mocks server common properties to all route handlers are in _cursive_. Specific properties of this plugin are in __bold__:
* __`host`__ _(String|Function)_: The proxy host. Equivalent to the [`express-http-proxy` `host` option](https://github.com/villadora/express-http-proxy#host), so it can also be a function.
* __`options`__ _(Object)_: Object containing any of the [options supported by the `express-http-proxy` package](https://github.com/villadora/express-http-proxy#options). Some of them are:
* __filter__ _(Function)_: [`filter` option](https://github.com/villadora/express-http-proxy#filter-supports-promises) for `express-http-proxy`.
* __userResDecorator__ _(Function)_: [`userResDecorator` option](https://github.com/villadora/express-http-proxy#userresdecorator-was-intercept-supports-promise) for `express-http-proxy`.
* __...__ all other [`express-http-proxy` options](https://github.com/villadora/express-http-proxy#options) are also supported.
> Tip: Note that the `delay` option is still valid for routes handled by this plugin, so you can use it to simulate that host responses are slow.
[website-url]: https://www.mocks-server.org
[main-distribution-url]: https://www.npmjs.com/package/@mocks-server/main
[options-url]: https://www.mocks-server.org/docs/configuration/options