fix: external source handling

packages/nocodb/src/modules/jobs/migration-jobs/nc_job_001_attachment.ts

@@ -169,6 +169,8 @@ export class AttachmentMigration {
           return;
         }
 
+        const isExternal = !source.isMeta();
+
         const model = await Model.get(context, fk_model_id);
 
         if (!model) {
@@ -189,6 +191,24 @@ export class AttachmentMigration {
           return;
         }
 
+        if (isExternal) {
+          try {
+            // run SELECT 1 to check if connection is working
+            // return if no response in 10 seconds
+            await Promise.race([
+              dbDriver.raw('SELECT 1'),
+              new Promise((resolve, reject) =>
+                setTimeout(() => reject(new Error('timeout')), 10000),
+              ),
+            ]);
+          } catch (e) {
+            this.log(
+              `External source ${source_id} (${source.alias}) is not accessible`,
+            );
+            return;
+          }
+        }
+
         const baseModel = await Model.getBaseModelSQL(context, {
           model,
           dbDriver,