When installing Dokku on a newly-created Linode server, you'll likely see an error during Docker installation:
Warning: current kernel is not supported by the linux-image-extra-virtual package. We have no AUFS support. Consider installing the packages linux-image-virtual kernel and linux-image-extra-virtual for AUFS support.
After 10 seconds, the installation will continue as normal.
This warning is the result of Linode using its own kernel, which does not support AUFS, instead of using the kernel supplied by Debian/Ubuntu. If you ignore the warning, Docker will fall back to using the DeviceMapper storage backend and Dokku will work normally. However, AUFS is better tested and will perform better.
To avoid this error message and use AUFS, follow the steps below to select the GRUB 2 kernel.
Dashboardassociated with your new server.
Configuration Profile. You should now be on the
Edit Configuration Profilepage.
Kernel menu. Change the "Kernel" option to "GRUB 2" and save your changes.
Bootbutton and your server is running, you will need to reboot it before continuing. Otherwise, you can now push the
Bootbutton to start your server and proceed with the normal Dokku installation.
Once your server comes back online, you'll be running Ubuntu's default kernel. You can now follow Dokku's normal installation instructions and
bootstrap.sh will take care of everything else.
Once you have fully installed Dokku and rebooted your server, you can verify that AUFS is being used with the terminal command:
docker info. If AUFS is being used, you should see
Storage Driver: aufs in the output.