Cache using fetch
Determine how to cache a resource by setting TTLs, custom cache keys, and cache headers in a fetch request.
export default { async fetch(request) { const url = new URL(request.url); // Only use the path for the cache key, removing query strings // and always store using HTTPS, for example, https://www.example.com/file-uri-here const someCustomKey = `https://${url.hostname}${url.pathname}`; let response = await fetch(request, { cf: { // Always cache this fetch regardless of content type // for a max of 5 seconds before revalidating the resource cacheTtl: 5, cacheEverything: true, //Enterprise only feature, see Cache API for other plans cacheKey: someCustomKey, }, }); // Reconstruct the Response object to make its headers mutable. response = new Response(response.body, response); // Set cache control headers to cache on browser for 25 minutes response.headers.set("Cache-Control", "max-age=1500"); return response; },};
export default { async fetch(request): Promise<Response> { const url = new URL(request.url); // Only use the path for the cache key, removing query strings // and always store using HTTPS, for example, https://www.example.com/file-uri-here const someCustomKey = `https://${url.hostname}${url.pathname}`; let response = await fetch(request, { cf: { // Always cache this fetch regardless of content type // for a max of 5 seconds before revalidating the resource cacheTtl: 5, cacheEverything: true, //Enterprise only feature, see Cache API for other plans cacheKey: someCustomKey, }, }); // Reconstruct the Response object to make its headers mutable. response = new Response(response.body, response); // Set cache control headers to cache on browser for 25 minutes response.headers.set("Cache-Control", "max-age=1500"); return response; },} satisfies ExportedHandler;
from pyodide.ffi import to_js as _to_jsfrom js import Response, URL, Object, fetch
def to_js(x): return _to_js(x, dict_converter=Object.fromEntries)
async def on_fetch(request): url = URL.new(request.url)
# Only use the path for the cache key, removing query strings # and always store using HTTPS, for example, https://www.example.com/file-uri-here some_custom_key = f"https://{url.hostname}{url.pathname}"
response = await fetch( request, cf=to_js({ # Always cache this fetch regardless of content type # for a max of 5 seconds before revalidating the resource "cacheTtl": 5, "cacheEverything": True, # Enterprise only feature, see Cache API for other plans "cacheKey": some_custom_key, }), )
# Reconstruct the Response object to make its headers mutable response = Response.new(response.body, response)
# Set cache control headers to cache on browser for 25 minutes response.headers["Cache-Control"] = "max-age=1500"
return response
use worker::*;
#[event(fetch)]async fn fetch(req: Request, _env: Env, _ctx: Context) -> Result<Response> { let url = req.url()?;
// Only use the path for the cache key, removing query strings // and always store using HTTPS, for example, https://www.example.com/file-uri-here let custom_key = format!( "https://{host}{path}", host = url.host_str().unwrap(), path = url.path() );
let request = Request::new_with_init( url.as_str(), &RequestInit { headers: req.headers().clone(), method: req.method(), cf: CfProperties { // Always cache this fetch regardless of content type // for a max of 5 seconds before revalidating the resource cache_ttl: Some(5), cache_everything: Some(true), // Enterprise only feature, see Cache API for other plans cache_key: Some(custom_key), ..CfProperties::default() }, ..RequestInit::default() }, )?;
let mut response = Fetch::Request(request).send().await?;
// Set cache control headers to cache on browser for 25 minutes let _ = response.headers_mut().set("Cache-Control", "max-age=1500"); Ok(response)}
// Force Cloudflare to cache an assetfetch(event.request, { cf: { cacheEverything: true } });
Setting the cache level to Cache Everything will override the default cacheability of the asset. For time-to-live (TTL), Cloudflare will still rely on headers set by the origin.
A request's cache key is what determines if two requests are the same for caching purposes. If a request has the same cache key as some previous request, then Cloudflare can serve the same cached response for both. For more about cache keys, refer to the Create custom cache keys documentation.
// Set cache key for this request to "some-string".fetch(event.request, { cf: { cacheKey: "some-string" } });
Normally, Cloudflare computes the cache key for a request based on the request's URL. Sometimes, though, you may like different URLs to be treated as if they were the same for caching purposes. For example, if your website content is hosted from both Amazon S3 and Google Cloud Storage - you have the same content in both places, and you can use a Worker to randomly balance between the two. However, you do not want to end up caching two copies of your content. You could utilize custom cache keys to cache based on the original request URL rather than the subrequest URL:
export default { async fetch(request) { let url = new URL(request.url);
if (Math.random() < 0.5) { url.hostname = "example.s3.amazonaws.com"; } else { url.hostname = "example.storage.googleapis.com"; }
let newRequest = new Request(url, request); return fetch(newRequest, { cf: { cacheKey: request.url }, }); },};
export default { async fetch(request): Promise<Response> { let url = new URL(request.url);
if (Math.random() < 0.5) { url.hostname = "example.s3.amazonaws.com"; } else { url.hostname = "example.storage.googleapis.com"; }
let newRequest = new Request(url, request); return fetch(newRequest, { cf: { cacheKey: request.url }, }); },} satisfies ExportedHandler;
Workers operating on behalf of different zones cannot affect each other's cache. You can only override cache keys when making requests within your own zone (in the above example event.request.url
was the key stored), or requests to hosts that are not on Cloudflare. When making a request to another Cloudflare zone (for example, belonging to a different Cloudflare customer), that zone fully controls how its own content is cached within Cloudflare; you cannot override it.
// Force response to be cached for 86400 seconds for 200 status// codes, 1 second for 404, and do not cache 500 errors.fetch(request, { cf: { cacheTtlByStatus: { "200-299": 86400, 404: 1, "500-599": 0 } },});
This option is a version of the cacheTtl
feature which chooses a TTL based on the response's status code and does not automatically set cacheEverything: true
. If the response to this request has a status code that matches, Cloudflare will cache for the instructed time, and override cache directives sent by the origin. You can review details on the cacheTtl
feature on the Request page.
Using custom cache keys and overrides based on response code, you can write a Worker that sets the TTL based on the response status code from origin, and request file type.
The following example demonstrates how you might use this to cache requests for streaming media assets:
export default { async fetch(request) { // Instantiate new URL to make it mutable const newRequest = new URL(request.url);
const customCacheKey = `${newRequest.hostname}${newRequest.pathname}`; const queryCacheKey = `${newRequest.hostname}${newRequest.pathname}${newRequest.search}`;
// Different asset types usually have different caching strategies. Most of the time media content such as audio, videos and images that are not user-generated content would not need to be updated often so a long TTL would be best. However, with HLS streaming, manifest files usually are set with short TTLs so that playback will not be affected, as this files contain the data that the player would need. By setting each caching strategy for categories of asset types in an object within an array, you can solve complex needs when it comes to media content for your application
const cacheAssets = [ { asset: "video", key: customCacheKey, regex: /(.*\/Video)|(.*\.(m4s|mp4|ts|avi|mpeg|mpg|mkv|bin|webm|vob|flv|m2ts|mts|3gp|m4v|wmv|qt))/, info: 0, ok: 31556952, redirects: 30, clientError: 10, serverError: 0, }, { asset: "image", key: queryCacheKey, regex: /(.*\/Images)|(.*\.(jpg|jpeg|png|bmp|pict|tif|tiff|webp|gif|heif|exif|bat|bpg|ppm|pgn|pbm|pnm))/, info: 0, ok: 3600, redirects: 30, clientError: 10, serverError: 0, }, { asset: "frontEnd", key: queryCacheKey, regex: /^.*\.(css|js)/, info: 0, ok: 3600, redirects: 30, clientError: 10, serverError: 0, }, { asset: "audio", key: customCacheKey, regex: /(.*\/Audio)|(.*\.(flac|aac|mp3|alac|aiff|wav|ogg|aiff|opus|ape|wma|3gp))/, info: 0, ok: 31556952, redirects: 30, clientError: 10, serverError: 0, }, { asset: "directPlay", key: customCacheKey, regex: /.*(\/Download)/, info: 0, ok: 31556952, redirects: 30, clientError: 10, serverError: 0, }, { asset: "manifest", key: customCacheKey, regex: /^.*\.(m3u8|mpd)/, info: 0, ok: 3, redirects: 2, clientError: 1, serverError: 0, }, ];
const { asset, regex, ...cache } = cacheAssets.find(({ regex }) => newRequest.pathname.match(regex)) ?? {};
const newResponse = await fetch(request, { cf: { cacheKey: cache.key, polish: false, cacheEverything: true, cacheTtlByStatus: { "100-199": cache.info, "200-299": cache.ok, "300-399": cache.redirects, "400-499": cache.clientError, "500-599": cache.serverError, }, cacheTags: ["static"], }, });
const response = new Response(newResponse.body, newResponse);
// For debugging purposes response.headers.set("debug", JSON.stringify(cache)); return response; },};
addEventListener("fetch", (event) => { return event.respondWith(handleRequest(event.request));});
async function handleRequest(request) { // Instantiate new URL to make it mutable const newRequest = new URL(request.url);
// Set `const` to be used in the array later on const customCacheKey = `${newRequest.hostname}${newRequest.pathname}`; const queryCacheKey = `${newRequest.hostname}${newRequest.pathname}${newRequest.search}`;
// Set all variables needed to manipulate Cloudflare's cache using the fetch API in the `cf` object. You will be passing these variables in the objects down below. const cacheAssets = [ { asset: "video", key: customCacheKey, regex: /(.*\/Video)|(.*\.(m4s|mp4|ts|avi|mpeg|mpg|mkv|bin|webm|vob|flv|m2ts|mts|3gp|m4v|wmv|qt))/, info: 0, ok: 31556952, redirects: 30, clientError: 10, serverError: 0, }, { asset: "image", key: queryCacheKey, regex: /(.*\/Images)|(.*\.(jpg|jpeg|png|bmp|pict|tif|tiff|webp|gif|heif|exif|bat|bpg|ppm|pgn|pbm|pnm))/, info: 0, ok: 3600, redirects: 30, clientError: 10, serverError: 0, }, { asset: "frontEnd", key: queryCacheKey, regex: /^.*\.(css|js)/, info: 0, ok: 3600, redirects: 30, clientError: 10, serverError: 0, }, { asset: "audio", key: customCacheKey, regex: /(.*\/Audio)|(.*\.(flac|aac|mp3|alac|aiff|wav|ogg|aiff|opus|ape|wma|3gp))/, info: 0, ok: 31556952, redirects: 30, clientError: 10, serverError: 0, }, { asset: "directPlay", key: customCacheKey, regex: /.*(\/Download)/, info: 0, ok: 31556952, redirects: 30, clientError: 10, serverError: 0, }, { asset: "manifest", key: customCacheKey, regex: /^.*\.(m3u8|mpd)/, info: 0, ok: 3, redirects: 2, clientError: 1, serverError: 0, }, ];
// the `.find` method is used to find elements in an array (`cacheAssets`), in this case, `regex`, which can passed to the .`match` method to match on file extensions to cache, since they are many media types in the array. If you want to add more types, update the array. Refer to https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find for more information. const { asset, regex, ...cache } = cacheAssets.find(({ regex }) => newRequest.pathname.match(regex)) ?? {};
const newResponse = await fetch(request, { cf: { cacheKey: cache.key, polish: false, cacheEverything: true, cacheTtlByStatus: { "100-199": cache.info, "200-299": cache.ok, "300-399": cache.redirects, "400-499": cache.clientError, "500-599": cache.serverError, }, cacheTags: ["static"], }, });
const response = new Response(newResponse.body, newResponse);
// For debugging purposes response.headers.set("debug", JSON.stringify(cache)); return response;}
The cache
mode can be set in fetch
options.
Currently Workers only support the no-store
mode for controlling the cache.
When no-store
is supplied the cache is bypassed on the way to the origin and the request is not cacheable.
fetch(request, { cache: 'no-store'});