feat(chromium): extra documentation and inclusion of header function …

…in all fetch calls

README.md

@@ -143,6 +143,25 @@ Chromiumly.configure({
 });
 ```
 
+### Advanced Authentication / Headers
+
+You can optionally pass in an async function to the client config to pass custom headers into the underlying `fetch` call to your Gotenberg instance.
+
+This is useful for cases where you might need to do things like custom service account auth (if hosting on Google cloud run, for example), include custom proxy headers, ec.
+
+Ex:
+
+```typescript
+Chromiumly.configure({
+  endpoint: "https://my-gotenberg-service-1234.us-central1.run.app",
+  addCustomHeadersFn: async () => ({
+    Authorization: `Bearer ${await generateIdToken()}`,
+  }),
+});
+```
+
+_Note: if you include username/password the created `Authorization` heaer will overwrite any you supply from the custom headers function._
+
 ## Modules
 
 Chromiumly introduces different classes that serve as wrappers to

src/chromium/converters/html.converter.ts

@@ -108,7 +108,8 @@ export class HtmlConverter extends Converter {
             this.endpoint,
             data,
             Chromiumly.getGotenbergApiBasicAuthUsername(),
-            Chromiumly.getGotenbergApiBasicAuthPassword()
+            Chromiumly.getGotenbergApiBasicAuthPassword(),
+            await Chromiumly.getAddCustomHeadersFn()()
         );
     }
 }

src/chromium/screenshots/html.screenshot.ts

@@ -81,7 +81,8 @@ export class HtmlScreenshot extends Screenshot {
             this.endpoint,
             data,
             Chromiumly.getGotenbergApiBasicAuthUsername(),
-            Chromiumly.getGotenbergApiBasicAuthPassword()
+            Chromiumly.getGotenbergApiBasicAuthPassword(),
+            await Chromiumly.getAddCustomHeadersFn()()
         );
     }
 }

src/chromium/screenshots/markdown.screenshot.ts

@@ -85,7 +85,8 @@ export class MarkdownScreenshot extends Screenshot {
             this.endpoint,
             data,
             Chromiumly.getGotenbergApiBasicAuthUsername(),
-            Chromiumly.getGotenbergApiBasicAuthPassword()
+            Chromiumly.getGotenbergApiBasicAuthPassword(),
+            await Chromiumly.getAddCustomHeadersFn()()
         );
     }
 }

src/chromium/screenshots/url.screenshot.ts

@@ -82,7 +82,8 @@ export class UrlScreenshot extends Screenshot {
             this.endpoint,
             data,
             Chromiumly.getGotenbergApiBasicAuthUsername(),
-            Chromiumly.getGotenbergApiBasicAuthPassword()
+            Chromiumly.getGotenbergApiBasicAuthPassword(),
+            await Chromiumly.getAddCustomHeadersFn()()
         );
     }
 }

src/main.config.ts

@@ -121,6 +121,7 @@ export class Chromiumly {
      * @param {string} config.endpoint - The Gotenberg service endpoint.
      * @param {string} [config.username] - The username for basic authentication.
      * @param {string} [config.password] - The password for basic authentication.
+     * @param {() => Promise<Record<string, string>>} [config.addCustomHeadersFn] - Optional async function to add custom headers to fetch
      */
     public static configure(config: {
         endpoint: string;