import {ApiError} from 'app/common/ApiError'; import {parseSubdomainStrictly} from 'app/common/gristUrls'; import {removeTrailingSlash} from 'app/common/gutil'; import {DocStatus, DocWorkerInfo, IDocWorkerMap} from 'app/server/lib/DocWorkerMap'; import log from 'app/server/lib/log'; import {adaptServerUrl} from 'app/server/lib/requestUtils'; import * as express from 'express'; import fetch, {Response as FetchResponse, RequestInit} from 'node-fetch'; import { getAssignmentId } from './idUtils'; /** * This method transforms a doc worker's public url as needed based on the request. * * For historic reasons, doc workers are assigned a public url at the time * of creation. In production/staging, this is of the form: * https://doc-worker-NNN-NNN-NNN-NNN.getgrist.com/v/VVVV/ * and in dev: * http://localhost:NNNN/v/VVVV/ * * Prior to support for different base domains, this was fine. Now that different * base domains are supported, a wrinkle arises. When a web client communicates * with a doc worker, it is important that it accesses the doc worker via a url * containing the same base domain as the web page the client is on (for cookie * purposes). Hence this method. * * If both the request and docWorkerUrl contain identifiable base domains (not localhost), * then the base domain of docWorkerUrl is replaced with that of the request. * * But wait, there's another wrinkle: custom domains. In this case, we have a single * domain available to serve a particular org from. This method will use the origin of req * and include a /dw/doc-worker-NNN-NNN-NNN-NNN/ * (or /dw/local-NNNN/) prefix in all doc worker paths. Once this is in place, it * will allow doc worker routing to be changed so it can be overlaid on a custom * domain. * * TODO: doc worker registration could be redesigned to remove the assumption * of a fixed base domain. */ export function customizeDocWorkerUrl( docWorkerUrlSeed: string|undefined, req: express.Request ): string|null { if (!docWorkerUrlSeed) { // When no doc worker seed, we're in single server mode. // Return null, to signify that the URL prefix serving the // current endpoint is the only one available. return null; } const docWorkerUrl = new URL(docWorkerUrlSeed); const workerSubdomain = parseSubdomainStrictly(docWorkerUrl.hostname).org; adaptServerUrl(docWorkerUrl, req); // We wish to migrate to routing doc workers by path, so insert a doc worker identifier // in the path (if not already present). if (!docWorkerUrl.pathname.startsWith('/dw/')) { // When doc worker is localhost, the port number is necessary and sufficient for routing. // Let's add a /dw/... prefix just for consistency. const workerIdent = workerSubdomain || `local-${docWorkerUrl.port}`; docWorkerUrl.pathname = `/dw/${workerIdent}${docWorkerUrl.pathname}`; } return docWorkerUrl.href; } /** * * Gets the worker responsible for a given assignment, and fetches a url * from the worker. * * If the fetch fails, we throw an exception, unless we see enough evidence * to unassign the worker and try again. * * - If GRIST_MANAGED_WORKERS is set, we assume that we've arranged * for unhealthy workers to be removed automatically, and that if a * fetch returns a 404 with specific content, it is proof that the * worker is no longer in existence. So if we see a 404 with that * specific content, we can safely de-list the worker from redis, * and repeat. * - If GRIST_MANAGED_WORKERS is not set, we accept a broader set * of failures as evidence of a missing worker. * * The specific content of a 404 that will be treated as evidence of * a doc worker not being present is: * - A json format body * - With a key called "message" * - With the value of "message" being "document worker not present" * In production, this is provided by a special doc-worker-* load balancer * rule. * */ export async function getWorker( docWorkerMap: IDocWorkerMap, assignmentId: string, urlPath: string, config: RequestInit = {} ) { if (!useWorkerPool()) { // This should never happen. We are careful to not use getWorker // when everything is on a single server, since it is burdensome // for self-hosted users to figure out the correct settings for // the server to be able to contact itself, and there are cases // of the defaults not working. throw new Error("AppEndpoint.getWorker was called unnecessarily"); } let docStatus: DocStatus|undefined; const workersAreManaged = Boolean(process.env.GRIST_MANAGED_WORKERS); for (;;) { docStatus = await docWorkerMap.assignDocWorker(assignmentId); const configWithTimeout = {timeout: 10000, ...config}; const fullUrl = removeTrailingSlash(docStatus.docWorker.internalUrl) + urlPath; try { const resp: FetchResponse = await fetch(fullUrl, configWithTimeout); if (resp.ok) { return { resp, docStatus, }; } if (resp.status === 403) { throw new ApiError("You do not have access to this document.", resp.status); } if (resp.status !== 404) { throw new ApiError(resp.statusText, resp.status); } let body: any; try { body = await resp.json(); } catch (e) { throw new ApiError(resp.statusText, resp.status); } if (!(body && body.message && body.message === 'document worker not present')) { throw new ApiError(resp.statusText, resp.status); } // This is a 404 with the expected content for a missing worker. } catch (e) { log.rawDebug(`AppEndpoint.getWorker failure`, { url: fullUrl, docId: assignmentId, status: e.status, message: String(e), workerId: docStatus.docWorker.id, }); // If workers are managed, no errors merit continuing except a 404. // Otherwise, we continue if we see a system error (e.g. ECONNREFUSED). // We don't accept timeouts since there is too much potential to // bring down a single-worker deployment that has a hiccup. if (workersAreManaged || !(e.type === 'system')) { throw e; } } log.warn(`fetch from ${fullUrl} failed convincingly, removing that worker`); await docWorkerMap.removeWorker(docStatus.docWorker.id); docStatus = undefined; } } export type DocWorkerInfoOrSelfPrefix = { docWorker: DocWorkerInfo, selfPrefix?: never, } | { docWorker?: never, selfPrefix: string }; export async function getDocWorkerInfoOrSelfPrefix( docId: string, docWorkerMap?: IDocWorkerMap | null, tag?: string ): Promise { if (!useWorkerPool()) { // Let the client know there is not a separate pool of workers, // so they should continue to use the same base URL for accessing // documents. For consistency, return a prefix to add into that // URL, as there would be for a pool of workers. It would be nice // to go ahead and provide the full URL, but that requires making // more assumptions about how Grist is configured. // Alternatives could be: have the client to send their base URL // in the request; or use headers commonly added by reverse proxies. const selfPrefix = "/dw/self/v/" + tag; return { selfPrefix }; } if (!docWorkerMap) { throw new Error('no worker map'); } const assignmentId = getAssignmentId(docWorkerMap, docId); const { docStatus } = await getWorker(docWorkerMap, assignmentId, '/status'); if (!docStatus) { throw new Error('no worker'); } return { docWorker: docStatus.docWorker }; } // Return true if document related endpoints are served by separate workers. export function useWorkerPool() { return process.env.GRIST_SINGLE_PORT !== 'true'; }