create molecule scenario and adapt role

defaults/main.yml

@@ -6,4 +6,5 @@ acme_certs_dir: "{{ acme_config_dir }}/certs"
 acme_accounts_dir: "{{ acme_config_dir }}/accounts"
 acme_account_key: "acme_account.key"
 acme_ssl_group: ssl-cert
-acme_challenge_dir: /var/www/acme
+acme_challenge_dir: /var/www/acme
+acme_domains: []

molecule/default/converge.yml

@@ -0,0 +1,6 @@
+---
+- name: Converge
+  hosts: all
+  
+  roles:
+    - ansible-role-acme

molecule/default/molecule.yml

@@ -0,0 +1,19 @@
+---
+dependency:
+  name: galaxy
+driver:
+  name: docker
+platforms:
+  - name: buster-acme-molecule
+    image: debian:buster-slim
+    pre_build_image: true
+  - name: focal-acme-molecule
+    image: ubuntu:focal
+    pre_build_image: true
+provisioner:
+  name: ansible
+  config_options:
+    defaults:
+      interpreter_python: /usr/bin/python3
+verifier:
+  name: ansible

molecule/default/prepare.yml

@@ -0,0 +1,10 @@
+- name: Prepare
+  hosts: all
+  gather_facts: no
+
+  tasks:
+    - name: Update apt cache
+      raw: apt update
+
+    - name: Install python3 package
+      raw: apt install -y --no-install-recommends python3

tasks/main.yml

@@ -1,9 +1,14 @@
 - name: Install ACME dependencies
-  apt:
+  package:
     name: python3-acme
     state: present
   tags: acme_install
 
+- name: Install SSL dependencies
+  package:
+    name: ssl-cert
+    state: present
+
 - name: Create Let's Encrypt config directories
   file:
     path: "{{ config_dir }}"