fix: allow absolute urls in public_folder (#5311)

packages/netlify-cms-core/src/reducers/__tests__/entries.spec.js

@@ -435,6 +435,22 @@ describe('entries', () => {
       ).toBe('../../static/media/image.png');
     });
 
+    it('should handle absolute public_folder', () => {
+      expect(
+        selectMediaFilePublicPath(
+          { public_folder: 'https://www.netlify.com/media' },
+          fromJS({
+            name: 'posts',
+            folder: 'posts',
+            public_folder: 'https://www.netlify.com/media',
+          }),
+          'image.png',
+          undefined,
+          undefined,
+        ),
+      ).toBe('https://www.netlify.com/media/image.png');
+    });
+
     it('should compile collection public folder template', () => {
       const slugConfig = {
         encoding: 'unicode',

packages/netlify-cms-core/src/reducers/entries.ts

@@ -59,6 +59,7 @@ import { trim, once, sortBy, set, orderBy, groupBy } from 'lodash';
 import { selectSortDataPath } from './collections';
 import { stringTemplate } from 'netlify-cms-lib-widgets';
 import { VIEW_STYLE_LIST } from '../constants/collectionViews';
+import { joinUrlPath } from '../lib/urlHelper';
 
 const { keyToPathArray } = stringTemplate;
 
@@ -790,6 +791,10 @@ export function selectMediaFilePublicPath(
     publicFolder = evaluateFolder(name, config, collection!, entryMap, field);
   }
 
+  if (isAbsolutePath(publicFolder)) {
+    return joinUrlPath(publicFolder, basename(mediaPath));
+  }
+
   return join(publicFolder, basename(mediaPath));
 }