How to create a specific user on a specific host - ansible

Question

There are several computers on the network, on each of them you need to create a user with a specific login and password.
I create users like this:
vars_prompt:
- name: "user_name"
prompt: "User name"
private: no
- name: "user_password"
prompt: "Enter a password for the user"
private: yes
encrypt: "md5_crypt"
confirm: yes
salt_size: 7
tasks:
- name: "add new user"
user:
name: "{{user_name}}"
password: "{{user_password}}"
shell: /bin/bash
Since there are many computers I don’t want to run a playbook a huge number of times. Ideally, I would like to implement the input of the list of hosts (computers) and the list of users. Password, in principle, you can do the same everywhere.

Answer 1

Loop the task
tasks:
- name: "add new user"
user:
name: "{{ item.user_name }}"
password: "{{ item.user_password }}"
shell: /bin/bash
loop: "{{ my_users }}"
and put the variable(s) my_users to host_vars
my_users:
- user_name: user1
user_password: password1
- user_name: user2
user_password: password2
Put common users to group_vars.
See Variable precedence: Where should I put a variable?
Use Ansible Vault to encrypt the passwords.

Answer 2

Here is an example of what you can try. Adapt to your needs.
Note: if the list of users is different for each host, just execute the playbook several times. Implementing this as a promptable play in ansible will just be a total pain and merely unusable.
In the example below, test1 and test2 are pointing to 2 docker containers I added in my demo_inventory.yml.
all:
hosts:
test1:
ansible_connection: docker
test2:
ansible_connection: docker
The hosts you enter will need to be correctly known by ansible for this to work.
This is the demo playbook test.yml
---
- name: Gather needed information
hosts: localhost
vars_prompt:
- name: hosts_entry
prompt: Enter comma separated list of hosts to target
private: false
- name: users_entry
prompt: Enter comma separated list of users to create
private: false
- name: user_password
prompt: Enter initial password applied to all users
encrypt: md5_crypt
confirm: true
salt_size: 7
tasks:
- name: Create a dynamic whatever_group with entered hosts
add_host:
name: "{{ item | trim }}"
groups:
- whatever_group
loop: "{{ hosts_entry.split(',') }}"
- name: Create a list of host for later reuse. Will be scoped to localhost
set_fact:
users_list: "{{ users_entry.split(',') }}"
- name: Store password for later reuse as vars_prompt are limited to play
set_fact:
user_password: "{{ user_password }}"
- name: Do the actual work
hosts: whatever_group
tasks:
- name: Make sure users are present
user:
name: "{{ item | trim }}"
password: "{{ hostvars['localhost'].user_password }}"
shell: /bin/bash
loop: "{{ hostvars['localhost'].users_list }}"
I created a play on localhost to gather the info from vars_prompt. In this play, I used add_host to create a whatever_group dynamically. Note the use of split to create list from a string with comma seperated elements in the input and of trim to remove the leading/trailing spaces (if user entered them). Since vars_prompt are limited in scope to the current play, I also used set_fact to get the users list and the password for future use.
On the next play, I target the whatever_group and run the user task. Note that since set_fact used previously scoped the variables to localhost, we have to use the hostvars magic variable to get the relevant information for the user loop and the password.
Here is the example run
$ ansible-playbook -i demo_inventory.yml test.yml
Enter comma separated list of hosts to target: test1, test2
Enter comma separated list of users to create: user1, user2, user3
Enter initial password applied to all users:
confirm Enter initial password applied to all users:
PLAY [Gather needed information] ***************************************************************
TASK [Gathering Facts] *************************************************************************
ok: [localhost]
TASK [Create a dynamic whatever_group with entered hosts] **************************************
changed: [localhost] => (item=test1)
changed: [localhost] => (item= test2)
TASK [Create a list of host for later reuse. Will be scoped to localhost] **********************
ok: [localhost]
TASK [Store password for later reuse as vars_prompt are limited to play] ***********************
ok: [localhost]
PLAY [Do the actual work] **********************************************************************
TASK [Gathering Facts] *************************************************************************
ok: [test1]
ok: [test2]
TASK [Make sure users are present] *************************************************************
changed: [test2] => (item=user1)
changed: [test1] => (item=user1)
changed: [test2] => (item= user2)
changed: [test1] => (item= user2)
changed: [test2] => (item= user3)
changed: [test1] => (item= user3)
PLAY RECAP *************************************************************************************
localhost : ok=4 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
test1 : ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
test2 : ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0