enable ipv6 for docker to retain proper source addresses for SPF

nginx_templates/conf.d/default.conf.template

@@ -1,5 +1,6 @@
 server {
     listen 80;
+    listen [::]:80;
 
     return 301 https://$host$request_uri;
 }

nginx_templates/ssl_listen.conf.template

@@ -1,4 +1,5 @@
 listen 443 ssl;
+listen [::]:443 ssl;
 
 http2 on;
 

templates/etc/docker/daemon.json

@@ -1,3 +1,41 @@
 {
-    "storage-driver": "overlay2"
-}
+    "storage-driver": "overlay2",
+    "ipv6": true,
+    "fixed-cidr-v6": "fd57:d7e4:f221::/64",
+    "experimental": true,
+    "ip6tables": true,
+    "default-address-pools": [
+        {
+            "base": "172.17.0.0/16",
+            "size": 16
+        },
+        {
+            "base": "172.18.0.0/16",
+            "size": 16
+        },
+        {
+            "base": "172.19.0.0/16",
+            "size": 16
+        },
+        {
+            "base": "172.20.0.0/14",
+            "size": 16
+        },
+        {
+            "base": "172.24.0.0/14",
+            "size": 16
+        },
+        {
+            "base": "172.28.0.0/14",
+            "size": 16
+        },
+        {
+            "base": "fd57:d7e4:f221:1::/64",
+            "size": 64
+        },
+        {
+            "base": "fd57:d7e4:f221:2::/64",
+            "size": 64
+        }
+    ]
+}