presto-admin keeps asking for a password

[exolab]

I am trying to run presto-admin on an AWS EMR cluster. Even though I think I have tried everything, it does not seem to be possible to get presto-admin to correctly authenticate with the nodes involved.

I can ssh to the master and nodes without a password (as either of the users 'hadoop', 'root' or 'ec2-user'). I can ssh from the master (where presto-admin is installed) to the core nodes without a password (as either of the users).

I have set a password:
sudo su -c 'echo "hadoop:blablabla" | chpasswd'

To avoid confusion, I have done that on all the nodes.

If I try using presto-admin as 'hadoop', using serial mode, I get asked for a password for 'hadoop':

[hadoop@ip-xyz ~]$ presto-admin -i /home/hadoop/.ssh/id_rsa catalog add my-catalog 
Deploying my-catalog.properties catalog configurations on: ec2-xyz.eu-central-1.compute.amazonaws.com 
[ec2-xyz.eu-central-1.compute.amazonaws.com] Login password for 'hadoop':

When I enter the password I have set previously, it does not work, nor give me an error. It just keeps asking for the password.

I have also tried running presto-admin as ec-user and root.

My config looks as follows

{
  "username": "hadoop",
  "port": "22",
  "coordinator": "ec2-xyz.eu-central-1.compute.amazonaws.com",
  "workers": ["ec2-abc.eu-central-1.compute.amazonaws.com", "ec2-def.eu-central-1.compute.amazonaws.com"],
  "java8_home":"/usr/bin/java"
}

This may well not be an issue, as it seems to be working for other people.