I have a wiki-family setup and I installed this extension on my shared media repository (similar to commons.wikimedia.org), however, none of the other wiki's (for example, en.wikipedia, fa.wikipedia) could generate thumbnails on demand anymore. Images and thumbnails that existed before the migration loaded from s3 without a problem. Thumbnails generate in s3 when the media repository wiki is the one making the request, just not the other wiki's in the family make the request. These are the shared upload settings I'm using:
$wgUseSharedUploads = true;
//$wgSharedUploadPath = 'https://example.com/images'; #old setting
$wgSharedUploadPath = 'https://examplebucket.s3.amazonaws.com'; #new setting
$wgHashedSharedUploadDirectory = true;
$wgSharedUploadDirectory = "images";
$wgFetchCommonsDescriptions = true;
$wgSharedUploadDBname = 'example_wikidbcommons';
$wgSharedUploadDBprefix = '';
$wgRepositoryBaseUrl = "https://example.com/File:";
This is the equivalent code using wgForeignFileRepos
$wgForeignFileRepos[] = [
'class' => 'ForeignDBRepo',
'name' => 'mywiki',
//'url' => "https://example.com/images", #old
'url' => "https://examplebucket.s3.amazonaws.com", #new
'directory' => 'images',
'hashLevels' => 2, // This must be the same for the other family member
'dbType' => $wgDBtype,
'dbServer' => $wgDBserver,
'dbUser' => $wgDBuser,
'dbPassword' => $wgDBpassword,
'dbFlags' => DBO_DEFAULT,
'dbName' => 'example_wikidbcommons',
'tablePrefix' => '',
'hasSharedCache' => false,
'descBaseUrl' => 'https://example.com/File:',
'fetchDescription' => true
];
I'm not sure what else I should be changing, $wgSharedUploadPath says "Thumbnails will also be looked for and generated in this directory."