refactor!: switch hosts variables to a flat layout

inventory/group_vars/all/vars.yml

@@ -1,9 +1,16 @@
-custom_base_user_account: '{{ vault_custom_base_user_account }}'
-custom_github_token: '{{ vault_custom_github_token }}'
-dns:
-  type: "dot"
-  udp: '{{ vault_groups.defaults.udp }}'
-  dot: '{{ vault_groups.defaults.dot }}'
-  doh: '{{ vault_groups.defaults.doh }}'
-network: "external"
-ip_dualstack: true
+---
+# global parameters
+custom_base_user_account: "{{ vault_custom_base_user_account }}"
+custom_github_token: "{{ vault_custom_github_token | default('') }}"
+
+# global (hosts' system parameters)
+## TODO: move to a CMDB
+global_dns_type: "dot"
+# empty values for dns{4,6} servers mean that servers will be retrieved dynamically from /etc/resolv.conf
+global_dns_udp_dns4: "{{ vault_global_dns_udp_dns4 }}"
+global_dns_udp_dns6: "{{ vault_global_dns_udp_dns6 }}"
+global_dns_dot_dns4: "{{ vault_global_dns_dot_dns4 }}"
+global_dns_dot_dns6: "{{ vault_global_dns_dot_dns6 }}"
+global_dns_doh_dns4: "{{ vault_global_dns_doh_dns4 }}"
+global_dns_doh_dns6: "{{ vault_global_dns_doh_dns6 }}"
+global_ip_dualstack: true

inventory/group_vars/internal/vars.yml

@@ -0,0 +1,8 @@
+# global
+global_dns_type: "udp"
+global_dns_udp_dns4: "" # force usage of DHCP provided values
+global_dns_udp_dns6: "" # force usage of DHCP provided values
+global_ip_dualstack: false
+
+# security role
+security_firewall_mangle_drop_privatenets: false