Using variables for file name and file contents in lineinfile module - ansible

Question

I am trying to read the contents of a file, store these in a variable and then insert them into another file if they don't already exist.
So, how I'm attempting to go about this is as follows:
# Create a variable that represents the path to the file that you want to read from
ssh_public_key_file: '../../jenkins_master/files/{{ hostvars[inventory_hostname]["environment"] }}/id_rsa.pub'
# Create a variable that represents the contents of this file:
ssh_public_key: "{{ lookup('file', '{{ ssh_public_key_file }}') }}"
I then use these variables in my Ansible playbook as follows:
- name: Install SSH authorized key
lineinfile: create=yes dest=~/.ssh/authorized_keys line=" {{ ssh_public_key }}" mode=0644
However, when I try and run the playbook, I get the following error message:
could not locate file in lookup: {{ ssh_public_key_file }}
Can anyone recommend a solution or suggest what I may have done wrong?
Thanks,
Seán

Answer 1

You have to change the line to:
# Create a variable that represents the contents of this file:
ssh_public_key: "{{ lookup('file', ssh_public_key_file) }}"
If you need to concatenate variables and strings you can do it like this:
# Example with two variables
ssh_public_key: "{{ lookup('file', var_1+var_2) }}"
# Example with string and variable
ssh_public_key: "{{ lookup('file', '~/config/'+var_1) }}"
. .

Answer 2

First I would make sure that your ssh_public_key_file variable is set up properly. If you add a task like the following what does it show?
- name: display variable
debug: var=ssh_public_key_file
If the output looks something like this then the variable isn't defined properly (eg. the "environment" fact doesn't exist for the host):
ok: [localhost] => {
"ssh_public_key_file": "../../jenkins_master/files/{{ hostvars[inventory_hostname][\"environment\"] }}/id_rsa.pub"
}
However if everything is defined properly then your output should show the variables replaced with their correct values:
ok: [localhost] => {
"ssh_public_key_file": "../../jenkins_master/files/foo/id_rsa.pub"
}
Once you've verified that then I would do the same thing with your ssh_public_key variable. Just output its value using the debug module. It should display as the contents of the public key file.
One other thing I would strongly suggest is to avoid using lineinfile altogether. Since you're working with SSH keys I would recommend you use the authorized_key module instead. It's a much cleaner way of managing authorized_keys files.