ansible: add getaddrinfo config to prefer IPv4

On some hosts, IPv6 connectivity is limited and may result in DNS
lookups returning IPv6 addresses that the host is unable to reach.
Add a config file for glibc's getaddrinfo function that configures
IPv4 addresses to have higher precedence for such hosts.

ansible/roles/bootstrap/files/gai.conf

@@ -0,0 +1,12 @@
+# getaddrinfo(3) configuration file
+# Settings to prefer IPv4 addresses for hosts with limited IPv6 connectivity.
+
+# Below settings are documented defaults but need to be duplicated since
+# setting any precedence line means the default table is not used.
+precedence  ::1/128       50
+precedence  ::/0          40
+precedence  2002::/16     30
+precedence ::/96          20
+
+# This line is changed from the default to give IPv4 higher precedence.
+precedence ::ffff:0:0/96  100

ansible/roles/bootstrap/tasks/partials/rhel8-s390x.yml

@@ -48,3 +48,11 @@
     insertafter: ":OUTPUT ACCEPT.*]"
     line: "-A INPUT -s 127.0.0.2/32 -d 127.0.0.1/32 -j ACCEPT"
   notify: restart iptables
+
+- name: Configure getaddrinfo to prefer IPv4 addresses
+  ansible.builtin.copy:
+    dest: /etc/gai.conf
+    group: root
+    mode: 0644
+    owner: root
+    src: "gai.conf"