Ansible: how to get dynamic service state with a variable within another - syntax

Question

I'm new to Ansible and trying to get a service state where the service name is dynamic and set by set_fact before in the playbook.
How can you build a variable within another variable?
I wish I could use something like that to display my service state :
{{ ansible_facts.services['{{ servicename }}'].state }}
But well it doesn't work.
So I tried this way with vars :
- name: set service name
ansible.builtin.set_fact:
servicename: "'myservice'"
when: ansible_distribution_major_version == "7"
- name: print service state
debug: msg={{ vars['ansible_facts.services[' + servicename + '].state'] }}
vars:
servicename: "{{ servicename }}"
I got the following error :
fatal: [myhost]: FAILED! => {"msg": "The task includes an option with an undefined variable. The error was: 'dict object' has no attribute u\"ansible_facts.services['myservice'].state\"\n\nThe error appears to be in '/etc/ansible/playbook/myplaybook.yaml': line 20, column 5, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n\n - name: print service state\n ^ here\n"}
When the following works just fine :
- name: print service state
debug:
msg: "{{ ansible_facts.services['myservice'].state }}"

Answer 1

Inside a {{ … }} block, you can access the variables directly. And from my point of view, you can leave the ansible_facts out, as well as the variable assignment in the second task.
This will do what you want (and as Zeitounator already wrote):
- hosts: localhost
vars:
services:
myservice:
state: foo
tasks:
- name: set service name
ansible.builtin.set_fact:
servicename: "myservice"
- name: print service state
debug:
msg: "{{ services[servicename].state }}"