Introduce APP_HOME_INTERNAL_URL

README.md

@@ -237,8 +237,9 @@ Grist can be configured in many ways. Here are the main environment variables it
 |------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | ALLOWED_WEBHOOK_DOMAINS            | comma-separated list of permitted domains to use in webhooks (e.g. webhook.site,zapier.com). You can set this to `*` to allow all domains, but if doing so, we recommend using a carefully locked-down proxy (see `GRIST_HTTPS_PROXY`) if you do not entirely trust users. Otherwise services on your internal network may become vulnerable to manipulation. |
 | APP_DOC_URL                        | doc worker url, set when starting an individual doc worker (other servers will find doc worker urls via redis)                                                                                                                                                                                                                                                |
-| APP_DOC_INTERNAL_URL               | like `APP_DOC_URL` but used by the home server to reach the server using an internal domain name resolution (like in a docker environment). Defaults to `APP_DOC_URL`                                                                                                                                                                                         |
+| APP_DOC_INTERNAL_URL               | like `APP_DOC_URL` but used by the home server to reach the server using an internal domain name resolution (like in a docker environment). You may only define this value in the doc worker. Defaults to `APP_DOC_URL`.                                                                                                                                      |
 | APP_HOME_URL                       | url prefix for home api (home and doc servers need this)                                                                                                                                                                                                                                                                                                      |
+| APP_HOME_INTERNAL_URL              | like `APP_HOME_URL` but used by the home server to reach any home workers using an internal domain name resolution (like in a docker environment). Defaults to `APP_HOME_URL`                                                                                                                                                                                 |
 | APP_STATIC_URL                     | url prefix for static resources                                                                                                                                                                                                                                                                                                                               |
 | APP_STATIC_INCLUDE_CUSTOM_CSS      | set to "true" to include custom.css (from APP_STATIC_URL) in static pages                                                                                                                                                                                                                                                                                     |
 | APP_UNTRUSTED_URL                  | URL at which to serve/expect plugin content.                                                                                                                                                                                                                                                                                                                  |

app/server/lib/FlexServer.ts

@@ -295,6 +295,13 @@ export class FlexServer implements GristServer {
     return homeUrl;
   }
 
+  /**
+   * Same as getDefaultHomeUrl, but for internal use.
+   */
+  public getDefaultHomeInternalUrl(): string {
+    return process.env.APP_HOME_INTERNAL_URL || this.getDefaultHomeUrl();
+  }
+
   /**
    * Get a url for the home server api, adapting it to match the base domain in the
    * requested url.  This adaptation is important for cookie-based authentication.
@@ -302,13 +309,20 @@ export class FlexServer implements GristServer {
    * If relPath is given, returns that path relative to homeUrl. If omitted, note that
    * getHomeUrl() will still return a URL ending in "/".
    */
-  public getHomeUrl(req: express.Request, relPath: string = ''): string {
+  public getHomeUrl(req: express.Request, relPath: string = '', defaultHomeUrl = this.getDefaultHomeUrl()): string {
     // Get the default home url.
-    const homeUrl = new URL(relPath, this.getDefaultHomeUrl());
+    const homeUrl = new URL(relPath, defaultHomeUrl);
     adaptServerUrl(homeUrl, req as RequestWithOrg);
     return homeUrl.href;
   }
 
+  /**
+   * Same as getHomeUrl, but for requesting internally.
+   */
+  public getHomeInternalUrl(req: express.Request, relPath?: string): string {
+    return this.getHomeUrl(req, relPath, this.getDefaultHomeInternalUrl());
+  }
+
   /**
    * Get a home url that is appropriate for the given document.  For now, this
    * returns a default that works for all documents.  That could change in future,

app/server/lib/GristServer.ts

@@ -35,6 +35,7 @@ export interface GristServer {
   settings?: Readonly<Record<string, unknown>>;
   getHost(): string;
   getHomeUrl(req: express.Request, relPath?: string): string;
+  getHomeInternalUrl(req: express.Request, relPath?: string): string;
   getHomeUrlByDocId(docId: string, relPath?: string): Promise<string>;
   getOwnUrl(): string;
   getOrgUrl(orgKey: string|number): Promise<string>;
@@ -127,6 +128,7 @@ export function createDummyGristServer(): GristServer {
     settings: {},
     getHost() { return 'localhost:4242'; },
     getHomeUrl() { return 'http://localhost:4242'; },
+    getHomeInternalUrl() { return 'http://localhost:4242'; },
     getHomeUrlByDocId() { return Promise.resolve('http://localhost:4242'); },
     getMergedOrgUrl() { return 'http://localhost:4242'; },
     getOwnUrl() { return 'http://localhost:4242'; },