61 lines
2.7 KiB
JavaScript
61 lines
2.7 KiB
JavaScript
import process from "node:process";
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/** Name of the env var containing the mapping */
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export const DEPLOYMENT_MAPPING_ENV_NAME = "CF_DEPLOYMENT_MAPPING";
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/** Version used for the latest worker */
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export const CURRENT_VERSION_ID = "current";
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let deploymentMapping;
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/**
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* Routes the request to the requested deployment.
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*
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* A specific deployment can be requested via:
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* - the `dpl` search parameter for assets
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* - the `x-deployment-id` for other requests
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*
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* When a specific deployment is requested, we route to that deployment via the preview URLs.
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* See https://developers.cloudflare.com/workers/configuration/previews/
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*
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* When the requested deployment is not supported a 400 response is returned.
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*
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* Notes:
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* - The re-routing is only active for the deployed version of the app (on a custom domain)
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* - Assets are also handled when `run_worker_first` is enabled.
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* See https://developers.cloudflare.com/workers/static-assets/binding/#run_worker_first
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*
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* @param request
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* @returns
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*/
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export function maybeGetSkewProtectionResponse(request) {
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// no early return as esbuild would not treeshake the code.
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if (__SKEW_PROTECTION_ENABLED__) {
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const url = new URL(request.url);
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// Skew protection is only active for the latest version of the app served on a custom domain.
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if (url.hostname === "localhost" || url.hostname.endsWith(".workers.dev")) {
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return undefined;
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}
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const requestDeploymentId = request.headers.get("x-deployment-id") ?? url.searchParams.get("dpl");
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if (!requestDeploymentId || requestDeploymentId === process.env.DEPLOYMENT_ID) {
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// The request does not specify a deployment id or it is the current deployment id
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return undefined;
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}
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deploymentMapping ??= process.env[DEPLOYMENT_MAPPING_ENV_NAME]
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? JSON.parse(process.env[DEPLOYMENT_MAPPING_ENV_NAME])
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: {};
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if (!(requestDeploymentId in deploymentMapping)) {
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// Unknown deployment id, serve the current version
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return undefined;
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}
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const version = deploymentMapping[requestDeploymentId];
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if (!version || version === CURRENT_VERSION_ID) {
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return undefined;
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}
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const versionDomain = version.split("-")[0];
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const hostname = `${versionDomain}-${process.env.CF_WORKER_NAME}.${process.env.CF_PREVIEW_DOMAIN}.workers.dev`;
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url.hostname = hostname;
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const requestToOlderDeployment = new Request(url, request);
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// Remove the origin header to prevent an error with POST requests
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const headers = new Headers(request.headers);
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headers.delete("origin");
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return fetch(requestToOlderDeployment, { headers });
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}
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}
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