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How to move files when you need sudo on the remote server

I wanted to upload some files to an EC2 instance.

I had an SSH key for the ec2-user on the instance, but I wanted to upload files to a directory that the ec2-user didn’t have permissions to write to. It could write to them using passwordless sudo, but not by default.

Steps:

  1. Try to upload the file with no authentication, it fails because of no SSH key:

    $ rsync nginx.conf ec2-user@1.2.3.4:/etc/nginx/nginx.conf
ec2-user@1.2.3.4: Permission denied (publickey,gssapi-keyex,gssapi-with-mic).
rsync: connection unexpectedly closed (0 bytes received so far) [sender]

  2. Add the --rsh flag to specify an SSH key to use. Now it can connect to the remote server, but the remote server’s filesystem permissions prevent the write:

    $ rsync --rsh "ssh -i ~/.ssh/my_ssh_key" nginx.conf ec2-user@1.2.3.4:/etc/nginx/nginx.conf
rsync: [receiver] mkstemp "/etc/nginx/.nginx.conf.NkcrAs" failed: Permission denied (13)

  3. Add the --rsync-path flag to specify what rsync command to run on the remote server. By prefixing this with sudo, we can now write into the directory:

    $ rsync --rsync-path="sudo rsync" --rsh "ssh -i ~/.ssh/my_ssh_key" nginx.conf ec2-user@1.2.3.4:/etc/nginx/nginx.conf