Ansible - multiple roles - ansible

Question

I am trying to run multiple roles using with_items command, however I am getting error:
"ERROR! 'item' is undefined"
role.yml:
---
- hosts: '{{ host }}'
become: yes
roles:
- role: "{{item}}"
with_items: "{{ roles }}"
Here is my command:
ansible-playbook -i ./inventory/Dev ./playbooks/role.yml --extra-vars='{"host": "db", "roles": ["mysql", "apache"]}'

Answer 1

You cannot do it this way. with_ loops are not valid for roles.
If anything, you need to provide a list of roles to the roles: directive, so the syntax would be just like for the list of host groups hosts: '{{ host }}'. The problem is: Ansible does not resolve the variable for roles, so roles: '{{ roles }}' does not work.
What you can do, however, is to use include_role module in which you can access the variables.
No, include_role module doesn't take {{ item }} from the with_items as a value for name either.
So the only workaround I can think of (assuming you don't want to process the JSON beforehand) is to the include the roles statically:
tasks:
- include_role:
name: "mysql"
when: "'mysql' in roles"
- include_role:
name: "apache"
when: "'apache' in roles"
The roles need to exist on the control machine anyway, so all their names are predefined.

Answer 2

You cannot use with_ loop with roles directive.
A simple solution would be to use normal yaml list like below:
---
- hosts: '{{ host }}'
become: yes
roles:
- myrole1
- myrole2
Another example where you could declare the roles as well as pass corresponding variables to the role would be like below:
---
- hosts: '{{ host }}'
become: yes
roles:
- role:
name: myrole1
vars:
host: "db1"
myroles:
- mysql1
- apache1
- role:
name: myrole2
vars:
host: "db2"
myroles:
- mysql2
- apache2
Also avoid using ansible keywords as your variable names
Finally your command to run your playbook will be as below:
ansible-playbook -i ./inventory/Dev ./playbooks/role.yml