Ansible Permission denied (public key) but ssh using same key works

Question

I'm running this Ansible ad-hoc command on Ubuntu 16.x (ansible ver. 2.2.1.0 and 2.2.2.0)

ansible host_alias -a "df -h" -u USER

where host_alias is the defined the ansible hosts file (defines an ec2 instance and its .pem file).

the host file looks like this:

[host_alias]

my_host.compute.amazonaws.com

private_key_file=/path/to/key/my_key.pem

I get this error:

private_key_file=/path/to/key/my_key.pem | UNREACHABLE! => {
    "changed": false, 
    "msg": "Failed to connect to the host via ssh: ssh: Could not resolve hostname private_key_file=/path/to/key/my_key.pem: Name or service not known\r\n", 
    "unreachable": true
}
my_host.compute.amazonaws.com | UNREACHABLE! => {
    "changed": false, 
    "msg": "Failed to connect to the host via ssh: Permission denied (publickey).\r\n", 
    "unreachable": true

The same host and key work fine when I ssh (defined by ~/.ssh/config). I have made triple sure the key is there and has read permissions. I also tried setting the ansible_user in the Ansible hosts file.

Any ideas?

techraf · Accepted Answer · 2017-04-11 22:50:57Z

3

Please check the format of the Ansible inventory file in the documentation.

You have defined two hosts in a host group named host_alias:

the first host is: my_host.compute.amazonaws.com,
the second host is: private_key_file=/path/to/key/my_key.pem.

Ansible complains it cannot connect to the second host:

Could not resolve hostname private_key_file=/path/to/key/my_key.pem

It also cannot connect to the first host, because the SSH key is not defined:

Failed to connect to the host via ssh: Permission denied (publickey).

On top of the mistake of splitting the hostname and the parameter into separate lines, you also got the name of the parameter wrong -- it should be ansible_ssh_private_key_file.

The parameters are listed in a later section of the same document.

Your inventory file should look like this:

[host_group_name]
my_host.compute.amazonaws.com ansible_ssh_private_key_file=/path/to/key/my_key.pem

and your command:

ansible host_group_name -a "df -h" -u USER

edited Apr 11, 2017 at 22:50

answered Apr 11, 2017 at 22:35

techraf

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2 Comments

craig399 Over a year ago

Thank you so much techraf! After making your changes I had to do two more things. Pass a -u USER on my my ansible cmd (I know I can add it to the ansible hosts file). And secondly, after adding the user, I got an error indicating the name was too long. I seem to remember this is why I must have tried breaking up the lines with a new line. I fixed the char length issue by using the IP. I can live with that. All good now. Thank you!

techraf Over a year ago

Most likely you are referring to this issue: ssh throws 'unix domain socket "too long"' error. There are some solutions suggested.

rakhee · Accepted Answer · 2017-04-11 22:38:15Z

-1

The second line needs to be dropped in the [host_alias] section. The above section is meant for hosts only. Once you do that try

ansible all -m ping

to check if you can ping the host.

answered Apr 11, 2017 at 22:38

rakhee

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