Salt: enable ipv6 on prod server

salt/pillar/prod.sls

@@ -6,3 +6,5 @@ nginx_worker_processes: auto
 postgresql_version: 10
 prometheus_ips: ['127.0.0.1']
 site_hostname: tildes.net
+ipv6_address: '2607:5300:0203:2dd8::'
+ipv6_gateway: '2607:5300:0203:2dff:ff:ff:ff:ff'

salt/salt/prod-config.sls

@@ -2,3 +2,16 @@
 /etc/apt/apt.conf.d/99force-ipv4:
   file.managed:
     - contents: 'Acquire::ForceIPv4 "true";'
+
+# Enable ipv6 networking
+/etc/network/interfaces:
+  file.append:
+    - text: |
+        iface eth0 inet6 static
+            address {{ pillar['ipv6_address'] }}
+            netmask 64
+
+        post-up sleep 5; /sbin/ip -family inet6 route add {{ pillar['ipv6_gateway'] }} dev eth0
+        post-up sleep 5; /sbin/ip -family inet6 route add default via {{ pillar['ipv6_gateway'] }}
+        pre-down /sbin/ip -family inet6 route del default via {{ pillar['ipv6_gateway'] }}
+        pre-down /sbin/ip -family inet6 route del {{ pillar['ipv6_gateway'] }} dev eth0