Fix delegation issue

When adding OSDs for a host not in the mons group, I discovered that the
commands were not run on the delegated host (the first mon) but on the
host with the OSDs to add. This can cause issues as cephadm may not be
configured correctly on this host.

Author: priteau

roles/cephadm/tasks/osds.yml

@@ -1,4 +1,9 @@
 ---
+# We need to register this as a variable, otherwise it will not be interpreted
+# correctly when setting ansible_host in the next task.
+- name: Set a fact about the Ansible host
+  set_fact:
+    mon_ansible_host: "{{ hostvars[inventory_hostname].ansible_host }}"
 
 - name: Add OSDs individually
   command:
@@ -14,4 +19,4 @@
   vars:
     # NOTE: Without this, the delegate hosts's ansible_host variable will not
     # be respected.
-    ansible_host: "{{ hostvars[inventory_hostname].ansible_host if 'mons' in group_names else hostvars[groups['mons'][0]].ansible_host }}"
+    ansible_host: "{{ mon_ansible_host if 'mons' in group_names else hostvars[groups['mons'][0]].ansible_host }}"