Ssh to localhost fails


I recently signed up for a cloud9 account and love it. However I ran into one roadblock that I can’t seem to figure out. The process I’m trying to run (hadoop) needs the ability to ssh to localhost. I generated a keypair but when I try to update authorized_keys, I get an error that its on a read only filesystem?

> ubuntu@joramun-hadoop-test-3019904:~$ ssh localhost
    Permission denied (publickey).
> ubuntu@joramun-hadoop-test-3019904:~$ sudo cat ~/.ssh/ >> ~/.ssh/authorized_keys
    bash: /home/ubuntu/.ssh/authorized_keys: Read-only file system


I have the same issue.

Has anyone succeeded to install Hadoop please?

Many thanks,