The dashboard of maas server shows a warning message:
Some of the required system profiles are missing. Run the maas-import-isos script to import Ubuntu isos and create the related profiles:
Run the above command, it will download some files from ubuntu servers.
reboot maas server when this command completed. The warning message disappeared.
Fixing this problem is required, otherwise you can't add node server successfully.
First, create a VM for Ubuntu server as usual. I will call it as node1.
Then choose "Multiple server install with MAAS" in the startup menu.
Set the hostname to node1.
Now join the maas server as the MAAS:
Now, I continue adding second node server into maas. But this time I didn't see the first option:
"maas MAAS Server -(10.112.x.175:80)"
I choosed "Specify MAAS by name or address" option and entered IP address:10.112.x.175.
The second node was added successfully.
Repeated it again, the third node was added.