(core) add housekeeping endpoints for cleaning doc snapshots+state

Summary:
This adds endpoints that allow the support user to remove unlisted
snapshots for a document, and to remove all action history for
a document.

This does increase what the support user can do, but not in a way
that would be particularly valuable to attack.  It would have some
destructive value, for removing history (removing unlisted
snapshots doesn't impact the user, by contrast).

This would simplify some maintenance operations.

Test Plan: added test for snapshots; tested states manually

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2699

app/gen-server/lib/Housekeeper.ts

@@ -1,12 +1,18 @@
+import { ApiError } from 'app/common/ApiError';
 import { Document } from 'app/gen-server/entity/Document';
 import { Workspace } from 'app/gen-server/entity/Workspace';
 import { HomeDBManager, Scope } from 'app/gen-server/lib/HomeDBManager';
 import { fromNow } from 'app/gen-server/sqlUtils';
+import { getAuthorizedUserId } from 'app/server/lib/Authorizer';
+import { expressWrap } from 'app/server/lib/expressWrap';
 import { GristServer } from 'app/server/lib/GristServer';
 import { IElectionStore } from 'app/server/lib/IElectionStore';
 import * as log from 'app/server/lib/log';
 import { IPermitStore } from 'app/server/lib/Permit';
+import { stringParam } from 'app/server/lib/requestUtils';
+import * as express from 'express';
 import fetch from 'node-fetch';
+import * as Fetch from 'node-fetch';
 
 const HOUSEKEEPER_PERIOD_MS = 1 * 60 * 60 * 1000;   // operate every 1 hour
 const AGE_THRESHOLD_OFFSET = '-30 days';            // should be an interval known by postgres + sqlite
@@ -115,6 +121,38 @@ export class Housekeeper {
     }
   }
 
+  public addEndpoints(app: express.Application) {
+    // Allow support user to perform housekeeping tasks for a specific
+    // document.  The tasks necessarily bypass user access controls.
+    // As such, it would be best if these endpoints not offer ways to
+    // read or write the content of a document.
+
+    // Remove unlisted snapshots that are not recorded in inventory.
+    // Once all such snapshots have been removed, there should be no
+    // further need for this endpoint.
+    app.post('/api/housekeeping/docs/:docId/snapshots/clean', this._withSupport(async (docId, headers) => {
+      const url = await this._server.getHomeUrlByDocId(docId, `/api/docs/${docId}/snapshots/remove`);
+      return fetch(url, {
+        method: 'POST',
+        body: JSON.stringify({ select: 'unlisted' }),
+        headers,
+      });
+    }));
+
+    // Remove action history from document.  This may be of occasional
+    // use, for allowing support to help users looking to purge some
+    // information that leaked into document history that they'd
+    // prefer not be there, until there's an alternative.
+    app.post('/api/housekeeping/docs/:docId/states/remove', this._withSupport(async (docId, headers) => {
+      const url = await this._server.getHomeUrlByDocId(docId, `/api/docs/${docId}/states/remove`);
+      return fetch(url, {
+        method: 'POST',
+        body: JSON.stringify({ keep: 1 }),
+        headers,
+      });
+    }));
+  }
+
   /**
    * For test purposes, removes any exclusive lock on housekeeping.
    */
@@ -159,4 +197,28 @@ export class Housekeeper {
   private _getThreshold() {
     return fromNow(this._dbManager.connection.driver.options.type, AGE_THRESHOLD_OFFSET);
   }
+
+  // Call a document endpoint with a permit, cleaning up after the call.
+  // Checks that the user is the support user.
+  private _withSupport(callback: (docId: string, headers: Record<string, string>) => Promise<Fetch.Response>): express.RequestHandler {
+    return expressWrap(async (req, res) => {
+      const userId = getAuthorizedUserId(req);
+      if (userId !== this._dbManager.getSupportUserId()) {
+        throw new ApiError('access denied', 403);
+      }
+      const docId = stringParam(req.params.docId);
+      const permitKey = await this._permitStore.setPermit({docId});
+      try {
+        const result = await callback(docId, {
+          Permit: permitKey,
+          'Content-Type': 'application/json',
+        });
+        res.status(result.status);
+        // Return JSON result, or an empty object if no result provided.
+        res.json(await result.json().catch(() => ({})));
+      } finally {
+        await this._permitStore.removePermit(permitKey);
+      }
+    });
+  }
 }

app/server/lib/FlexServer.ts

@@ -1106,9 +1106,10 @@ export class FlexServer implements GristServer {
   }
 
   public async addHousekeeper() {
-    if (this._check('housekeeper', 'start', 'homedb', 'map')) { return; }
+    if (this._check('housekeeper', 'start', 'homedb', 'map', 'json', 'api-mw')) { return; }
     const store = this._docWorkerMap;
     this.housekeeper = new Housekeeper(this.dbManager, this, store, store);
+    this.housekeeper.addEndpoints(this.app);
     await this.housekeeper.start();
   }
 

app/server/mergedServerMain.ts

@@ -104,7 +104,6 @@ export async function main(port: number, serverTypes: ServerType[],
   if (includeHome) {
     if (!includeApp) {
       server.addUsage();
-      await server.addHousekeeper();
     }
     if (!includeDocs) {
       server.addDocApiForwarder();
@@ -115,9 +114,8 @@ export async function main(port: number, serverTypes: ServerType[],
     if (!includeApp) {
       server.addHomeApi();
       server.addBillingApi();
-    }
-    if (!includeApp) {
       server.addNotifier();
+      await server.addHousekeeper();
     }
     server.addLoginRoutes();
     server.addBillingPages();