# make-fetch-happen [![npm version](https://img.shields.io/npm/v/make-fetch-happen.svg)](https://npm.im/make-fetch-happen) [![license](https://img.shields.io/npm/l/make-fetch-happen.svg)](https://npm.im/make-fetch-happen) [![Travis](https://img.shields.io/travis/npm/make-fetch-happen.svg)](https://travis-ci.org/npm/make-fetch-happen) [![Coverage Status](https://coveralls.io/repos/github/npm/make-fetch-happen/badge.svg?branch=latest)](https://coveralls.io/github/npm/make-fetch-happen?branch=latest) [`make-fetch-happen`](https://github.com/npm/make-fetch-happen) is a Node.js library that wraps [`minipass-fetch`](https://github.com/npm/minipass-fetch) with additional features [`minipass-fetch`](https://github.com/npm/minipass-fetch) doesn't intend to include, including HTTP Cache support, request pooling, proxies, retries, [and more](#features)! ## Install `$ npm install --save make-fetch-happen` ## Table of Contents * [Example](#example) * [Features](#features) * [Contributing](#contributing) * [API](#api) * [`fetch`](#fetch) * [`fetch.defaults`](#fetch-defaults) * [`minipass-fetch` options](#minipass-fetch-options) * [`make-fetch-happen` options](#extra-options) * [`opts.cachePath`](#opts-cache-path) * [`opts.cache`](#opts-cache) * [`opts.cacheAdditionalHeaders`](#opts-cache-additional-headers) * [`opts.proxy`](#opts-proxy) * [`opts.noProxy`](#opts-no-proxy) * [`opts.ca, opts.cert, opts.key`](#https-opts) * [`opts.maxSockets`](#opts-max-sockets) * [`opts.retry`](#opts-retry) * [`opts.onRetry`](#opts-onretry) * [`opts.integrity`](#opts-integrity) * [`opts.dns`](#opts-dns) * [Message From Our Sponsors](#wow) ### Example ```javascript const fetch = require('make-fetch-happen').defaults({ cachePath: './my-cache' // path where cache will be written (and read) }) fetch('https://registry.npmjs.org/make-fetch-happen').then(res => { return res.json() // download the body as JSON }).then(body => { console.log(`got ${body.name} from web`) return fetch('https://registry.npmjs.org/make-fetch-happen', { cache: 'no-cache' // forces a conditional request }) }).then(res => { console.log(res.status) // 304! cache validated! return res.json().then(body => { console.log(`got ${body.name} from cache`) }) }) ``` ### Features * Builds around [`minipass-fetch`](https://npm.im/minipass-fetch) for the core [`fetch` API](https://fetch.spec.whatwg.org) implementation * Request pooling out of the box * Quite fast, really * Automatic HTTP-semantics-aware request retries * Cache-fallback automatic "offline mode" * Built-in request caching following full HTTP caching rules (`Cache-Control`, `ETag`, `304`s, cache fallback on error, etc). * Node.js Stream support * Transparent gzip and deflate support * [Subresource Integrity](https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity) support * Proxy support (http, https, socks, socks4, socks5. via [`@npmcli/agent`](https://npm.im/@npmcli/agent)) * DNS cache (via ([`@npmcli/agent`](https://npm.im/@npmcli/agent)) #### `> fetch(uriOrRequest, [opts]) -> Promise` This function implements most of the [`fetch` API](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch): given a `uri` string or a `Request` instance, it will fire off an http request and return a Promise containing the relevant response. If `opts` is provided, the [`minipass-fetch`-specific options](#minipass-fetch-options) will be passed to that library. There are also [additional options](#extra-options) specific to make-fetch-happen that add various features, such as HTTP caching, integrity verification, proxy support, and more. ##### Example ```javascript fetch('https://google.com').then(res => res.buffer()) ``` #### `> fetch.defaults([defaultUrl], [defaultOpts])` Returns a new `fetch` function that will call `make-fetch-happen` using `defaultUrl` and `defaultOpts` as default values to any calls. A defaulted `fetch` will also have a `.defaults()` method, so they can be chained. ##### Example ```javascript const fetch = require('make-fetch-happen').defaults({ cachePath: './my-local-cache' }) fetch('https://registry.npmjs.org/make-fetch-happen') // will always use the cache ``` #### `> minipass-fetch options` The following options for `minipass-fetch` are used as-is: * method * body * redirect * follow * timeout * compress * size These other options are modified or augmented by make-fetch-happen: * headers - Default `User-Agent` set to make-fetch happen. `Connection` is set to `keep-alive` or `close` automatically depending on `opts.agent`. For more details, see [the documentation for `minipass-fetch` itself](https://github.com/npm/minipass-fetch#options). #### `> make-fetch-happen options` make-fetch-happen augments the `minipass-fetch` API with additional features available through extra options. The following extra options are available: * [`opts.cachePath`](#opts-cache-path) - Cache target to read/write * [`opts.cache`](#opts-cache) - `fetch` cache mode. Controls cache *behavior*. * [`opts.cacheAdditionalHeaders`](#opts-cache-additional-headers) - Store additional headers in the cache * [`opts.proxy`](#opts-proxy) - Proxy agent * [`opts.noProxy`](#opts-no-proxy) - Domain segments to disable proxying for. * [`opts.ca, opts.cert, opts.key, opts.strictSSL`](#https-opts) * [`opts.localAddress`](#opts-local-address) * [`opts.maxSockets`](#opts-max-sockets) * [`opts.retry`](#opts-retry) - Request retry settings * [`opts.onRetry`](#opts-onretry) - a function called whenever a retry is attempted * [`opts.integrity`](#opts-integrity) - [Subresource Integrity](https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity) metadata. * [`opts.dns`](#opts-dns) - DNS cache options * [`opts.agent`](#opts-agent) - http/https/proxy/socks agent options. See [`@npmcli/agent`](https://npm.im/@npmcli/agent) for more info. #### `> opts.cachePath` A string `Path` to be used as the cache root for [`cacache`](https://npm.im/cacache). **NOTE**: Requests will not be cached unless their response bodies are consumed. You will need to use one of the `res.json()`, `res.buffer()`, etc methods on the response, or drain the `res.body` stream, in order for it to be written. The default cache manager also adds the following headers to cached responses: * `X-Local-Cache`: Path to the cache the content was found in * `X-Local-Cache-Key`: Unique cache entry key for this response * `X-Local-Cache-Mode`: Always `stream` to indicate how the response was read from cacache * `X-Local-Cache-Hash`: Specific integrity hash for the cached entry * `X-Local-Cache-Status`: One of `miss`, `hit`, `stale`, `revalidated`, `updated`, or `skip` to signal how the response was created * `X-Local-Cache-Time`: UTCString of the cache insertion time for the entry Using [`cacache`](https://npm.im/cacache), a call like this may be used to manually fetch the cached entry: ```javascript const h = response.headers cacache.get(h.get('x-local-cache'), h.get('x-local-cache-key')) // grab content only, directly: cacache.get.byDigest(h.get('x-local-cache'), h.get('x-local-cache-hash')) ``` ##### Example ```javascript fetch('https://registry.npmjs.org/make-fetch-happen', { cachePath: './my-local-cache' }) // -> 200-level response will be written to disk ``` #### `> opts.cache` This option follows the standard `fetch` API cache option. This option will do nothing if [`opts.cachePath`](#opts-cache-path) is null. The following values are accepted (as strings): * `default` - Fetch will inspect the HTTP cache on the way to the network. If there is a fresh response it will be used. If there is a stale response a conditional request will be created, and a normal request otherwise. It then updates the HTTP cache with the response. If the revalidation request fails (for example, on a 500 or if you're offline), the stale response will be returned. * `no-store` - Fetch behaves as if there is no HTTP cache at all. * `reload` - Fetch behaves as if there is no HTTP cache on the way to the network. Ergo, it creates a normal request and updates the HTTP cache with the response. * `no-cache` - Fetch creates a conditional request if there is a response in the HTTP cache and a normal request otherwise. It then updates the HTTP cache with the response. * `force-cache` - Fetch uses any response in the HTTP cache matching the request, not paying attention to staleness. If there was no response, it creates a normal request and updates the HTTP cache with the response. * `only-if-cached` - Fetch uses any response in the HTTP cache matching the request, not paying attention to staleness. If there was no response, it returns a network error. (Can only be used when request’s mode is "same-origin". Any cached redirects will be followed assuming request’s redirect mode is "follow" and the redirects do not violate request’s mode.) (Note: option descriptions are taken from https://fetch.spec.whatwg.org/#http-network-or-cache-fetch) ##### Example ```javascript const fetch = require('make-fetch-happen').defaults({ cachePath: './my-cache' }) // Will error with ENOTCACHED if we haven't already cached this url fetch('https://registry.npmjs.org/make-fetch-happen', { cache: 'only-if-cached' }) // Will refresh any local content and cache the new response fetch('https://registry.npmjs.org/make-fetch-happen', { cache: 'reload' }) // Will use any local data, even if stale. Otherwise, will hit network. fetch('https://registry.npmjs.org/make-fetch-happen', { cache: 'force-cache' }) ``` #### `> opts.cacheAdditionalHeaders` The following headers are always stored in the cache when present: - `cache-control` - `content-encoding` - `content-language` - `content-type` - `date` - `etag` - `expires` - `last-modified` - `link` - `location` - `pragma` - `vary` This option allows a user to store additional custom headers in the cache. ##### Example ```javascript fetch('https://registry.npmjs.org/make-fetch-happen', { cacheAdditionalHeaders: ['my-custom-header'], }) ``` #### `> opts.proxy` A string or `new url.URL()`-d URI to proxy through. Different Proxy handlers will be used depending on the proxy's protocol. Additionally, `process.env.HTTP_PROXY`, `process.env.HTTPS_PROXY`, and `process.env.PROXY` are used if present and no `opts.proxy` value is provided. (Pending) `process.env.NO_PROXY` may also be configured to skip proxying requests for all, or specific domains. ##### Example ```javascript fetch('https://registry.npmjs.org/make-fetch-happen', { proxy: 'https://corporate.yourcompany.proxy:4445' }) fetch('https://registry.npmjs.org/make-fetch-happen', { proxy: { protocol: 'https:', hostname: 'corporate.yourcompany.proxy', port: 4445 } }) ``` #### `> opts.noProxy` If present, should be a comma-separated string or an array of domain extensions that a proxy should _not_ be used for. This option may also be provided through `process.env.NO_PROXY`. #### `> opts.ca, opts.cert, opts.key, opts.strictSSL` These values are passed in directly to the HTTPS agent and will be used for both proxied and unproxied outgoing HTTPS requests. They mostly correspond to the same options the `https` module accepts, which will be themselves passed to `tls.connect()`. `opts.strictSSL` corresponds to `rejectUnauthorized`. #### `> opts.localAddress` Passed directly to `http` and `https` request calls. Determines the local address to bind to. #### `> opts.maxSockets` Default: 15 Maximum number of active concurrent sockets to use for the underlying Http/Https/Proxy agents. This setting applies once per spawned agent. 15 is probably a _pretty good value_ for most use-cases, and balances speed with, uh, not knocking out people's routers. 🤓 #### `> opts.retry` An object that can be used to tune request retry settings. Retries will only be attempted on the following conditions: * Request method is NOT `POST` AND * Request status is one of: `408`, `420`, `429`, or any status in the 500-range. OR * Request errored with `ECONNRESET`, `ECONNREFUSED`, `EADDRINUSE`, `ETIMEDOUT`, or the `fetch` error `request-timeout`. The following are worth noting as explicitly not retried: * `getaddrinfo ENOTFOUND` and will be assumed to be either an unreachable domain or the user will be assumed offline. If a response is cached, it will be returned immediately. If `opts.retry` is `false`, it is equivalent to `{retries: 0}` If `opts.retry` is a number, it is equivalent to `{retries: num}` The following retry options are available if you want more control over it: * retries * factor * minTimeout * maxTimeout * randomize For details on what each of these do, refer to the [`retry`](https://npm.im/retry) documentation. ##### Example ```javascript fetch('https://flaky.site.com', { retry: { retries: 10, randomize: true } }) fetch('http://reliable.site.com', { retry: false }) fetch('http://one-more.site.com', { retry: 3 }) ``` #### `> opts.onRetry` A function called with the response or error which caused the retry whenever one is attempted. ##### Example ```javascript fetch('https://flaky.site.com', { onRetry(cause) { console.log('we will retry because of', cause) } }) ``` #### `> opts.integrity` Matches the response body against the given [Subresource Integrity](https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity) metadata. If verification fails, the request will fail with an `EINTEGRITY` error. `integrity` may either be a string or an [`ssri`](https://npm.im/ssri) `Integrity`-like. ##### Example ```javascript fetch('https://registry.npmjs.org/make-fetch-happen/-/make-fetch-happen-1.0.0.tgz', { integrity: 'sha1-o47j7zAYnedYFn1dF/fR9OV3z8Q=' }) // -> ok fetch('https://malicious-registry.org/make-fetch-happen/-/make-fetch-happen-1.0.0.tgz', { integrity: 'sha1-o47j7zAYnedYFn1dF/fR9OV3z8Q=' }) // Error: EINTEGRITY ```

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