add option to enable model preforking for samba

* reduces number of process and hopefully ram usage
* default of role is standard model

ad-server-replication/defaults/main.yml

 ---
 
 ad_admin_password: samba-admin
+smb_model_prefork: false
+smb_prefork_children: 4  # since it is default in 4.10
+

ad-server-replication/tasks/main.yml

@@ -98,6 +98,17 @@
   tags:
     - ad-server
 
+- name: ensure we have a default enviroment
+  template:
+    src: samba_environ.j2
+    dest: /etc/default/samba
+    owner: root
+    group: root
+    mode: '0644'
+  notify: restart samba-ad-dc server
+  tags:
+    - ad-server
+
 - name: ensure samba-ad-dc unit is running, enabled and not masked
   systemd:
     name: samba-ad-dc

ad-server-replication/templates/samba_environ.j2

+{% if smb_model_prefork %}
+SAMBAOPTIONS="--model prefork"
+{% endif %}

ad-server-replication/templates/smb.conf.j2

@@ -24,6 +24,11 @@
         tls keyfile = {{smb_tls_key}}
         tls certfile = {{smb_tls_cert}}
 
+{% if smb_model_prefork %}
+        prefork children = {{ smb_prefork_children }}
+{% endif %}
+
+
 
 [netlogon]
         path = /var/lib/samba/sysvol/{{ domain }}/scripts

ad-server/defaults/main.yml

 ---
 
 ad_admin_password: samba-admin
+smb_model_prefork: false
+smb_prefork_children: 4  # since it is default in 4.10

ad-server/tasks/main.yml

@@ -69,6 +69,17 @@
   tags:
     - ad-server
 
+- name: ensure we have a default enviroment
+  template:
+    src: samba_environ.j2
+    dest: /etc/default/samba
+    owner: root
+    group: root
+    mode: '0644'
+  notify: restart samba-ad-dc server
+  tags:
+    - ad-server
+
 - name: ensure samba-ad-dc unit is running, enabled and not masked
   systemd:
     name: samba-ad-dc

ad-server/templates/samba_environ.j2

+{% if smb_model_prefork %}
+SAMBAOPTIONS="--model prefork"
+{% endif %}

ad-server/templates/smb.conf.j2

@@ -24,6 +24,10 @@
         tls keyfile = {{smb_tls_key}}
         tls certfile = {{smb_tls_cert}}
 
+{% if smb_model_prefork %}
+	prefork children = {{ smb_prefork_children }}
+{% endif %}
+
 
 [netlogon]
         path = /var/lib/samba/sysvol/{{ domain }}/scripts