network: add ipv6 only global option

docs/ansible/vars.md

@@ -43,6 +43,8 @@ Some variables of note include:
 * *ip6* - IPv6 address to use for binding services. (host var)
   If *enable_dual_stack_networks* is set to ``true`` and *ip6* is defined,
   kubelet's ``--node-ip`` and node's ``InternalIP`` will be the combination of *ip* and *ip6*.
+  If *enable_ipv6only_stack_networks* is set to ``true``,
+  kubelet's ``--node-ip`` and node's ``InternalIP`` will be use only *ip6*.
 * *loadbalancer_apiserver* - If defined, all hosts will connect to this
   address instead of localhost for kube_control_planes and kube_control_plane[0] for
   kube_nodes. See more details in the
@@ -85,6 +87,8 @@ following default cluster parameters:
 
 * *enable_dual_stack_networks* - Setting this to true will provision both IPv4 and IPv6 networking for pods and services.
 
+* *enable_ipv6only_stack_networks* - Setting this to true will provision IPv6 only networking for pods and services.
+
 * *kube_service_addresses_ipv6* - Subnet for cluster IPv6 IPs (default is ``fd85:ee78:d8a6:8607::1000/116``). Must not overlap with ``kube_pods_subnet_ipv6``.
 
 * *kube_pods_subnet_ipv6* - Subnet for Pod IPv6 IPs (default is ``fd85:ee78:d8a6:8607::1:0000/112``). Must not overlap with ``kube_service_addresses_ipv6``.
@@ -155,6 +159,7 @@ and ``kube_pods_subnet``, for example from the ``172.18.0.0/16``.
 ## Enabling Dual Stack (IPV4 + IPV6) networking
 
 If *enable_dual_stack_networks* is set to ``true``, Dual Stack networking will be enabled in the cluster. This will use the default IPv4 and IPv6 subnets specified in the defaults file in the ``kubespray-defaults`` role, unless overridden of course. The default config will give you room for up to 256 nodes with 126 pods per node, and up to 4096 services.
+Also you can use *enable_ipv6only_stack_networks* for ipv6 only networking.
 
 ## DNS variables
 

inventory/sample/group_vars/k8s_cluster/k8s-cluster.yml

@@ -100,19 +100,22 @@ kube_network_node_prefix: 24
 # Configure Dual Stack networking (i.e. both IPv4 and IPv6)
 enable_dual_stack_networks: false
 
+# Configure IPv6 only
+enable_ipv6only_stack_networks: false
+
 # Kubernetes internal network for IPv6 services, unused block of space.
-# This is only used if enable_dual_stack_networks is set to true
+# This is used if enable_dual_stack_networks or enable_ipv6only_stack_networks is set to true
 # This provides 4096 IPv6 IPs
 kube_service_addresses_ipv6: fd85:ee78:d8a6:8607::1000/116
 
 # Internal network. When used, it will assign IPv6 addresses from this range to individual pods.
 # This network must not already be in your network infrastructure!
-# This is only used if enable_dual_stack_networks is set to true.
+# This is used if enable_dual_stack_networks or enable_ipv6only_stack_networks is set to true
 # This provides room for 256 nodes with 254 pods per node.
 kube_pods_subnet_ipv6: fd85:ee78:d8a6:8607::1:0000/112
 
 # IPv6 subnet size allocated to each for pods.
-# This is only used if enable_dual_stack_networks is set to true
+# This is used if enable_dual_stack_networks or enable_ipv6only_stack_networks is set to true
 # This provides room for 254 pods per node.
 kube_network_node_prefix_ipv6: 120
 

roles/container-engine/cri-dockerd/templates/cri-dockerd.service.j2

@@ -7,7 +7,7 @@ Requires=cri-dockerd.socket
 
 [Service]
 Type=notify
-ExecStart={{ bin_dir }}/cri-dockerd --container-runtime-endpoint {{ cri_socket }} --cni-conf-dir=/etc/cni/net.d --cni-bin-dir=/opt/cni/bin --network-plugin=cni --pod-cidr={{ kube_pods_subnet }} --pod-infra-container-image={{ pod_infra_image_repo }}:{{ pod_infra_version }} --log-level {{ cri_dockerd_log_level }} {% if enable_dual_stack_networks %}--ipv6-dual-stack=True{% endif %}
+ExecStart={{ bin_dir }}/cri-dockerd --container-runtime-endpoint {{ cri_socket }} --cni-conf-dir=/etc/cni/net.d --cni-bin-dir=/opt/cni/bin --network-plugin=cni --pod-cidr={{ [kube_pods_subnet if not enable_ipv6only_stack_networks, kube_pods_subnet_ipv6 if (enable_dual_stack_networks or enable_ipv6only_stack_networks)] | reject('match', '^$') | join(',') }}{{ '' }} --pod-infra-container-image={{ pod_infra_image_repo }}:{{ pod_infra_version }} --log-level {{ cri_dockerd_log_level }} {% if enable_dual_stack_networks %}--ipv6-dual-stack=True{% endif %}
 
 ExecReload=/bin/kill -s HUP $MAINPID
 TimeoutSec=0

roles/kubernetes/control-plane/tasks/kubeadm-secondary.yml

@@ -43,8 +43,8 @@
 
 - name: Wait for k8s apiserver
   wait_for:
-    host: "{{ kubeadm_discovery_address.split(':')[0] }}"
-    port: "{{ kubeadm_discovery_address.split(':')[1] }}"
+    host: "{{ kubeadm_discovery_address | regex_replace(':\\d+$', '') }}"
+    port: "{{ kubeadm_discovery_address.split(':')[-1] }}"
     timeout: 180
 
 

roles/kubernetes/control-plane/tasks/kubeadm-setup.yml

@@ -25,16 +25,16 @@
 
 - name: Kubeadm | aggregate all SANs
   set_fact:
-    apiserver_sans: "{{ (sans_base + groups['kube_control_plane'] + sans_lb + sans_lb_ip + sans_supp + sans_access_ip + sans_ip + sans_address + sans_override + sans_hostname + sans_fqdn + sans_kube_vip_address) | unique }}"
+    apiserver_sans: "{{ (sans_base + groups['kube_control_plane'] + sans_apiserver_ip + sans_lb + sans_lb_ip + sans_supp + sans_access_ip + sans_ip + sans_address + sans_override + sans_hostname + sans_fqdn + sans_kube_vip_address) | unique }}"
   vars:
     sans_base:
       - "kubernetes"
       - "kubernetes.default"
       - "kubernetes.default.svc"
       - "kubernetes.default.svc.{{ dns_domain }}"
-      - "{{ kube_apiserver_ip }}"
       - "localhost"
       - "127.0.0.1"
+    sans_apiserver_ip: "{{ [kube_apiserver_ip] if not enable_ipv6only_stack_networks else [] }}"
     sans_lb: "{{ [apiserver_loadbalancer_domain_name] if apiserver_loadbalancer_domain_name is defined else [] }}"
     sans_lb_ip: "{{ [loadbalancer_apiserver.address] if loadbalancer_apiserver is defined and loadbalancer_apiserver.address is defined else [] }}"
     sans_supp: "{{ supplementary_addresses_in_ssl_keys if supplementary_addresses_in_ssl_keys is defined else [] }}"

roles/kubernetes/control-plane/templates/kubeadm-config.v1beta3.yaml.j2

@@ -94,9 +94,9 @@ dns:
   imageTag: {{ coredns_image_tag }}
 networking:
   dnsDomain: {{ dns_domain }}
-  serviceSubnet: "{{ kube_service_addresses }}{{ ',' + kube_service_addresses_ipv6 if enable_dual_stack_networks else '' }}"
+  serviceSubnet: "{{ [kube_service_addresses if not enable_ipv6only_stack_networks, kube_service_addresses_ipv6 if (enable_dual_stack_networks or enable_ipv6only_stack_networks)] | reject('match', '^$') | join(',') }}{{ '' }}"
 {% if kube_network_plugin is defined and kube_network_plugin not in ["kube-ovn"] %}
-  podSubnet: "{{ kube_pods_subnet }}{{ ',' + kube_pods_subnet_ipv6 if enable_dual_stack_networks else '' }}"
+  podSubnet: "{{ [kube_pods_subnet if not enable_ipv6only_stack_networks, kube_pods_subnet_ipv6 if (enable_dual_stack_networks or enable_ipv6only_stack_networks)] | reject('match', '^$') | join(',') }}{{ '' }}"
 {% endif %}
 {% if kubeadm_feature_gates %}
 featureGates:
@@ -143,7 +143,7 @@ apiServer:
     etcd-servers-overrides: "/events#{{ etcd_events_access_addresses_semicolon }}"
 {% endif %}
     service-node-port-range: {{ kube_apiserver_node_port_range }}
-    service-cluster-ip-range: "{{ kube_service_addresses }}{{ ',' + kube_service_addresses_ipv6 if enable_dual_stack_networks else '' }}"
+    service-cluster-ip-range: "{{ [kube_service_addresses if not enable_ipv6only_stack_networks, kube_service_addresses_ipv6 if (enable_dual_stack_networks or enable_ipv6only_stack_networks)] | reject('match', '^$') | join(',') }}{{ '' }}"
     kubelet-preferred-address-types: "{{ kubelet_preferred_address_types }}"
     profiling: "{{ kube_profiling }}"
     request-timeout: "{{ kube_apiserver_request_timeout }}"
@@ -293,18 +293,18 @@ controllerManager:
     node-monitor-grace-period: {{ kube_controller_node_monitor_grace_period }}
     node-monitor-period: {{ kube_controller_node_monitor_period }}
 {% if kube_network_plugin is defined and kube_network_plugin not in ["kube-ovn"] %}
-    cluster-cidr: "{{ kube_pods_subnet }}{{ ',' + kube_pods_subnet_ipv6 if enable_dual_stack_networks else '' }}"
+    cluster-cidr: "{{ [kube_pods_subnet if not enable_ipv6only_stack_networks, kube_pods_subnet_ipv6 if (enable_dual_stack_networks or enable_ipv6only_stack_networks)] | reject('match', '^$') | join(',') }}{{ '' }}"
 {% endif %}
-    service-cluster-ip-range: "{{ kube_service_addresses }}{{ ',' + kube_service_addresses_ipv6 if enable_dual_stack_networks else '' }}"
+    service-cluster-ip-range: "{{ [kube_service_addresses if not enable_ipv6only_stack_networks, kube_service_addresses_ipv6 if (enable_dual_stack_networks or enable_ipv6only_stack_networks)] | reject('match', '^$') | join(',') }}{{ '' }}"
 {% if kube_network_plugin is defined and kube_network_plugin == "calico" and not calico_ipam_host_local %}
     allocate-node-cidrs: "false"
-{% else %}
-{% if enable_dual_stack_networks %}
+{% elif enable_ipv6only_stack_networks %}
+    node-cidr-mask-size-ipv6: "{{ kube_network_node_prefix_ipv6 }}"
+{% elif enable_dual_stack_networks %}
     node-cidr-mask-size-ipv4: "{{ kube_network_node_prefix }}"
     node-cidr-mask-size-ipv6: "{{ kube_network_node_prefix_ipv6 }}"
 {% else %}
     node-cidr-mask-size: "{{ kube_network_node_prefix }}"
-{% endif %}
 {% endif %}
     profiling: "{{ kube_profiling }}"
     terminated-pod-gc-threshold: "{{ kube_controller_terminated_pod_gc_threshold }}"
@@ -383,7 +383,7 @@ clientConnection:
   kubeconfig: {{ kube_proxy_client_kubeconfig }}
   qps: {{ kube_proxy_client_qps }}
 {% if kube_network_plugin is defined and kube_network_plugin not in ["kube-ovn"] %}
-clusterCIDR: "{{ kube_pods_subnet }}{{ ',' + kube_pods_subnet_ipv6 if enable_dual_stack_networks else '' }}"
+clusterCIDR: "{{ [kube_pods_subnet if not enable_ipv6only_stack_networks, kube_pods_subnet_ipv6 if (enable_dual_stack_networks or enable_ipv6only_stack_networks)] | reject('match', '^$') | join(',') }}{{ '' }}"
 {% endif %}
 configSyncPeriod: {{ kube_proxy_config_sync_period }}
 conntrack:

roles/kubernetes/control-plane/templates/kubeadm-config.v1beta4.yaml.j2

@@ -106,9 +106,9 @@ dns:
   imageTag: {{ coredns_image_tag }}
 networking:
   dnsDomain: {{ dns_domain }}
-  serviceSubnet: "{{ kube_service_addresses }}{{ ',' + kube_service_addresses_ipv6 if enable_dual_stack_networks else '' }}"
+  serviceSubnet: "{{ [kube_service_addresses if not enable_ipv6only_stack_networks, kube_service_addresses_ipv6 if (enable_dual_stack_networks or enable_ipv6only_stack_networks)] | reject('match', '^$') | join(',') }}{{ '' }}"
 {% if kube_network_plugin is defined and kube_network_plugin not in ["kube-ovn"] %}
-  podSubnet: "{{ kube_pods_subnet }}{{ ',' + kube_pods_subnet_ipv6 if enable_dual_stack_networks else '' }}"
+  podSubnet: "{{ [kube_pods_subnet if not enable_ipv6only_stack_networks, kube_pods_subnet_ipv6 if (enable_dual_stack_networks or enable_ipv6only_stack_networks)] | reject('match', '^$') | join(',') }}{{ '' }}"
 {% endif %}
 {% if kubeadm_feature_gates %}
 featureGates:
@@ -169,7 +169,7 @@ apiServer:
   - name: service-node-port-range
     value: "{{ kube_apiserver_node_port_range }}"
   - name: service-cluster-ip-range
-    value: "{{ kube_service_addresses }}{{ ',' + kube_service_addresses_ipv6 if enable_dual_stack_networks else '' }}"
+    value: "{{ [kube_service_addresses if not enable_ipv6only_stack_networks, kube_service_addresses_ipv6 if (enable_dual_stack_networks or enable_ipv6only_stack_networks)] | reject('match', '^$') | join(',') }}{{ '' }}"
   - name: kubelet-preferred-address-types
     value: "{{ kubelet_preferred_address_types }}"
   - name: profiling
@@ -351,23 +351,24 @@ controllerManager:
     value: "{{ kube_controller_node_monitor_period }}"
 {% if kube_network_plugin is defined and kube_network_plugin not in ["kube-ovn"] %}
   - name: cluster-cidr
-    value: "{{ kube_pods_subnet }}{{ ',' + kube_pods_subnet_ipv6 if enable_dual_stack_networks else '' }}"
+    value: "{{ [kube_pods_subnet if not enable_ipv6only_stack_networks, kube_pods_subnet_ipv6 if (enable_dual_stack_networks or enable_ipv6only_stack_networks)] | reject('match', '^$') | join(',') }}{{ '' }}"
 {% endif %}
   - name: service-cluster-ip-range
-    value: "{{ kube_service_addresses }}{{ ',' + kube_service_addresses_ipv6 if enable_dual_stack_networks else '' }}"
+    value: "{{ [kube_service_addresses if not enable_ipv6only_stack_networks, kube_service_addresses_ipv6 if (enable_dual_stack_networks or enable_ipv6only_stack_networks)] | reject('match', '^$') | join(',') }}{{ '' }}"
 {% if kube_network_plugin is defined and kube_network_plugin == "calico" and not calico_ipam_host_local %}
   - name: allocate-node-cidrs
     value: "false"
-{% else %}
-{% if enable_dual_stack_networks %}
+{% elif enable_ipv6only_stack_networks %}
+  - name: node-cidr-mask-size-ipv6
+    value: "{{ kube_network_node_prefix_ipv6 }}"
+{% elif enable_dual_stack_networks %}
   - name: node-cidr-mask-size-ipv4
     value: "{{ kube_network_node_prefix }}"
   - name: node-cidr-mask-size-ipv6
     value: "{{ kube_network_node_prefix_ipv6 }}"
 {% else %}
   - name: node-cidr-mask-size
     value: "{{ kube_network_node_prefix }}"
-{% endif %}
 {% endif %}
   - name: profiling
     value: "{{ kube_profiling }}"
@@ -478,7 +479,7 @@ clientConnection:
   kubeconfig: {{ kube_proxy_client_kubeconfig }}
   qps: {{ kube_proxy_client_qps }}
 {% if kube_network_plugin is defined and kube_network_plugin not in ["kube-ovn"] %}
-clusterCIDR: "{{ kube_pods_subnet }}{{ ',' + kube_pods_subnet_ipv6 if enable_dual_stack_networks else '' }}"
+clusterCIDR: "{{ [kube_pods_subnet if not enable_ipv6only_stack_networks, kube_pods_subnet_ipv6 if (enable_dual_stack_networks or enable_ipv6only_stack_networks)] | reject('match', '^$') | join(',') }}{{ '' }}"
 {% endif %}
 configSyncPeriod: {{ kube_proxy_config_sync_period }}
 conntrack:

roles/kubernetes/node/defaults/main.yml

@@ -1,6 +1,6 @@
 ---
 # advertised host IP for kubelet. This affects network plugin config. Take caution
-kubelet_address: "{{ ip | default(fallback_ip) }}{{ (',' + ip6) if enable_dual_stack_networks and ip6 is defined else '' }}"
+kubelet_address: "{{ [ip | default(fallback_ip) if not enable_ipv6only_stack_networks, ip6 | default(fallback_ip6) if (enable_dual_stack_networks or enable_ipv6only_stack_networks)] | reject('match', '^$') | join(',') }}{{ '' }}"
 
 # bind address for kubelet. Set to 0.0.0.0 to listen on all interfaces
 kubelet_bind_address: "{{ ip | default('0.0.0.0') }}"

roles/kubernetes/node/templates/loadbalancer/haproxy.cfg.j2

@@ -22,7 +22,7 @@ defaults
 {% if loadbalancer_apiserver_healthcheck_port is defined -%}
 frontend healthz
   bind 0.0.0.0:{{ loadbalancer_apiserver_healthcheck_port }}
-  {% if enable_dual_stack_networks -%}
+  {% if enable_dual_stack_networks or enable_ipv6only_stack_networks -%}
   bind :::{{ loadbalancer_apiserver_healthcheck_port }}
   {% endif -%}
   mode http
@@ -31,7 +31,7 @@ frontend healthz
 
 frontend kube_api_frontend
   bind 127.0.0.1:{{ loadbalancer_apiserver_port|default(kube_apiserver_port) }}
-  {% if enable_dual_stack_networks -%}
+  {% if enable_dual_stack_networks or enable_ipv6only_stack_networks -%}
   bind [::1]:{{ loadbalancer_apiserver_port|default(kube_apiserver_port) }};
   {% endif -%}
   mode tcp

roles/kubernetes/node/templates/loadbalancer/nginx.conf.j2

@@ -20,7 +20,7 @@ stream {
 
   server {
     listen        127.0.0.1:{{ loadbalancer_apiserver_port|default(kube_apiserver_port) }};
-    {% if enable_dual_stack_networks -%}
+    {% if enable_dual_stack_networks or enable_ipv6only_stack_networks -%}
     listen        [::1]:{{ loadbalancer_apiserver_port|default(kube_apiserver_port) }};
     {% endif -%}
     proxy_pass    kube_apiserver;
@@ -44,7 +44,7 @@ http {
   {% if loadbalancer_apiserver_healthcheck_port is defined -%}
   server {
     listen {{ loadbalancer_apiserver_healthcheck_port }};
-    {% if enable_dual_stack_networks -%}
+    {% if enable_dual_stack_networks or enable_ipv6only_stack_networks -%}
     listen [::]:{{ loadbalancer_apiserver_healthcheck_port }};
     {% endif -%}
     location /healthz {

roles/kubernetes/preinstall/tasks/0080-system-configurations.yml

@@ -84,7 +84,7 @@
     value: "1"
     state: present
     reload: true
-  when: enable_dual_stack_networks | bool
+  when: (enable_dual_stack_networks or enable_ipv6only_stack_networks) | bool
 
 - name: Check if we need to set fs.may_detach_mounts
   stat:

roles/kubernetes/preinstall/tasks/0090-etchosts.yml

@@ -3,7 +3,11 @@
   set_fact:
     etc_hosts_inventory_block: |-
       {% for item in (groups['k8s_cluster'] + groups['etcd'] | default([]) + groups['calico_rr'] | default([])) | unique -%}
-      {% if 'access_ip' in hostvars[item] or 'ip' in hostvars[item] or 'ansible_default_ipv4' in hostvars[item] -%}
+      {% if enable_ipv6only_stack_networks -%}
+      {{ hostvars[item]['access_ip_v6'] | default(hostvars[item]['ip6'] | default(hostvars[item]['ansible_default_ipv6']['address'])) }}
+      {%- if ('ansible_hostname' in hostvars[item] and item != hostvars[item]['ansible_hostname']) %} {{ hostvars[item]['ansible_hostname'] }}.{{ dns_domain }} {{ hostvars[item]['ansible_hostname'] }} {% else %} {{ item }}.{{ dns_domain }} {{ item }} {% endif %}
+
+      {% else %}
       {{ hostvars[item]['access_ip'] | default(hostvars[item]['ip'] | default(hostvars[item]['ansible_default_ipv4']['address'])) }}
       {%- if ('ansible_hostname' in hostvars[item] and item != hostvars[item]['ansible_hostname']) %} {{ hostvars[item]['ansible_hostname'] }}.{{ dns_domain }} {{ hostvars[item]['ansible_hostname'] }} {% else %} {{ item }}.{{ dns_domain }} {{ item }} {% endif %}
 

roles/kubespray-defaults/defaults/main/main.yml

@@ -227,6 +227,9 @@ kube_network_node_prefix: 24
 # Configure Dual Stack networking (i.e. both IPv4 and IPv6)
 enable_dual_stack_networks: false
 
+# Configure only IPv6 networking
+enable_ipv6only_stack_networks: false
+
 # Kubernetes internal network for IPv6 services, unused block of space.
 # This is only used if enable_dual_stack_networks is set to true
 # This provides 4096 IPv6 IPs
@@ -247,7 +250,7 @@ kube_network_node_prefix_ipv6: 120
 # listening on.
 # NOTE: loadbalancer_apiserver_localhost somewhat alters the final API enpdoint
 # access IP value (automatically evaluated below)
-kube_apiserver_ip: "{{ kube_service_addresses | ansible.utils.ipaddr('net') | ansible.utils.ipaddr(1) | ansible.utils.ipaddr('address') }}"
+kube_apiserver_ip: "{{ kube_service_addresses_ipv6 if enable_ipv6only_stack_networks else kube_service_addresses | ansible.utils.ipaddr('net') | ansible.utils.ipaddr(1) | ansible.utils.ipaddr('address') }}"
 
 # NOTE: If you specific address/interface and use loadbalancer_apiserver_localhost
 # loadbalancer_apiserver_localhost (nginx/haproxy) will deploy on control plane nodes on 127.0.0.1:{{ loadbalancer_apiserver_port | default(kube_apiserver_port) }} too.
@@ -548,9 +551,9 @@ ssl_ca_dirs: |-
 
 # Vars for pointing to kubernetes api endpoints
 kube_apiserver_count: "{{ groups['kube_control_plane'] | length }}"
-kube_apiserver_address: "{{ ip | default(hostvars[inventory_hostname]['fallback_ip']) }}"
+kube_apiserver_address: "{{ ip6 | default(hostvars[inventory_hostname]['fallback_ip6']) if enable_ipv6only_stack_networks else ip | default(hostvars[inventory_hostname]['fallback_ip']) }}"
 kube_apiserver_access_address: "{{ access_ip | default(kube_apiserver_address) }}"
-first_kube_control_plane_address: "{{ hostvars[groups['kube_control_plane'][0]]['access_ip'] | default(hostvars[groups['kube_control_plane'][0]]['ip'] | default(hostvars[groups['kube_control_plane'][0]]['fallback_ip'])) }}"
+first_kube_control_plane_address: "{{ hostvars[groups['kube_control_plane'][0]]['access_ip'] | default(hostvars[groups['kube_control_plane'][0]]['ip'] | default(hostvars[groups['kube_control_plane'][0]]['fallback_ip'])) if not enable_ipv6only_stack_networks else hostvars[groups['kube_control_plane'][0]]['access_ip_v6'] | default(hostvars[groups['kube_control_plane'][0]]['ip6'] | default(hostvars[groups['kube_control_plane'][0]]['fallback_ip6'])) }}"
 loadbalancer_apiserver_localhost: "{{ loadbalancer_apiserver is not defined }}"
 loadbalancer_apiserver_type: "nginx"
 # applied if only external loadbalancer_apiserver is defined, otherwise ignored

roles/kubespray-defaults/tasks/main.yaml

@@ -16,7 +16,17 @@
     - name: Set fallback_ip
       set_fact:
         fallback_ip: "{{ ansible_default_ipv4.address | d('127.0.0.1') }}"
-      when: fallback_ip is not defined
+      when: fallback_ip6 is not defined
+    - name: Gather ansible_default_ipv6
+      setup:
+        gather_subset: '!all,network'
+        filter: "ansible_default_ipv6"
+      when: ansible_default_ipv6 is not defined
+      ignore_unreachable: true
+    - name: Set fallback_ip6
+      set_fact:
+        fallback_ip6: "{{ ansible_default_ipv6.address | d('::1') }}"
+      when: fallback_ip6 is not defined
 
     - name: Set no_proxy
       import_tasks: no_proxy.yml