Improve thumbnail generation with Azure file share

When deploying Confluence in an Azure environment, thumbnails won't generate properly without extra configuration.

Environment

• Azure deployment of Confluence Data Center
• Linux VM
• Azure file share used for shared home directory, mounted to a directory in the Linux VM, with default mount options (set via /etc/fstab)

Steps to reproduce

• Mount an Azure file share to a Linux directory as the share-home
• Add PNG attachments to a page
• Edit the page to add the image to the page

Expected results

• Thumbnails generate properly

Actual results

• Thumbnails don't generate and show a spinner on screen. In the filesystem, 0-length thumbnail files may be created.

Resolution

Modify mount options in /etc/fstab by one of the following ways:

1. Re-configure the mount options to set the uid and gid specifically to the user (and the user's group) that runs the application. For example, if you have a dedicated user called confluence and it's in a group called confluence, you will set uid=confluence and gid=confluence in your mount options.
   

   //testesourceroupdiag.file.core.windows.net/testazurefs /home/testazure/atlassian/shared-home cifs nofail,vers=3.0,credentials=/etc/smbcredentials/testesourceroupdiag.cred,uid=confluence,gid=confluence,file_mode=0777,dir_mode=0777,serverino
   

2. Add "noperm" to the mount options:
   

   //testesourceroupdiag.file.core.windows.net/testazurefs /home/testazure/atlassian/shared-home cifs noperm,nofail,vers=3.0,credentials=/etc/smbcredentials/testesourceroupdiag.cred,file_mode=0777,dir_mode=0777,serverino