Don't bind to ipv4 if prefer-ipv6 is true

Following https://tracker.ceph.com/issues/52867 we need to tell the OSD
which address family to use via the ms_bind_ipv4/6 config flags.
I added them to the ceph.conf template and updated the config hook.
Closes-bug: #2019251

Change-Id: Ifbd59c204a82109e2b71991078f59537f6db42d3

hooks/ceph_hooks.py

@@ -488,6 +488,8 @@ def get_ceph_context(upgrading=False):
         cephcontext['bdev_discard'] = False
 
     if config('prefer-ipv6'):
+        cephcontext['ms_bind_ipv4'] = False
+        cephcontext['ms_bind_ipv6'] = True
         dynamic_ipv6_address = get_ipv6_addr()[0]
         if not public_network:
             cephcontext['public_addr'] = dynamic_ipv6_address

templates/ceph.conf

@@ -15,6 +15,12 @@ err to syslog = {{ use_syslog }}
 clog to syslog = {{ use_syslog }}
 debug osd = {{ loglevel }}/5
 
+{% if ms_bind_ipv6 %}
+ms_bind_ipv6 = true
+{%- endif %}
+{%- if ms_bind_ipv4 == false %}
+ms_bind_ipv4 = false
+{% endif %}
 {% if ceph_public_network is string %}
 public network = {{ ceph_public_network }}
 {%- endif %}