Avoid unconditional fact gathering

One way to improve the performance of Ansible is through fact caching.
Rather than gather facts in every play, we can configure Ansible to
cache them in a persistent store. An example Ansible configuration for
doing this is as follows:

[defaults]
gathering = smart
fact_caching = jsonfile
fact_caching_connection = ./facts
fact_caching_timeout = 86400

While this mostly just works, there are a few places where we
unconditionally gather facts using the setup module. This change
modifies these to only gather facts when necessary.

We no longer execute the MichaelRigart.interfaces role using become:
true, since it may gather facts and we do not want it to do so as root.
The role uses become where necessary.

Change-Id: I9984a187fc6c0496ada489bb8eef36e44d695aac
Story: 2007492
Task: 39216

ansible/baremetal-compute-serial-console.yml

@@ -47,6 +47,7 @@
            gather_subset: min
          delegate_to: localhost
          delegate_facts: true
+         when: not hostvars.localhost.module_setup | default(false)
 
        - name: Reserve TCP ports for ironic serial consoles
          include_role:

ansible/ip-allocation.yml

@@ -15,6 +15,7 @@
       delegate_to: localhost
       delegate_facts: true
       run_once: true
+      when: not hostvars.localhost.module_setup | default(false)
 
 - name: Ensure IP addresses are allocated
   hosts: seed-hypervisor:seed:overcloud

ansible/kayobe-ansible-user.yml

@@ -36,6 +36,7 @@
 
 - name: Ensure the Kayobe Ansible user account exists
   hosts: kayobe_user_bootstrap_required_True
+  gather_facts: false
   tags:
     - kayobe-ansible-user
   vars:

ansible/kayobe-target-venv.yml

@@ -19,6 +19,8 @@
     - block:
         - name: Gather facts
           setup:
+          when: not module_setup | default(false)
+          register: gather_facts
 
         - name: Ensure the Python virtualenv package is installed
           package:
@@ -82,6 +84,16 @@
         ansible_python_interpreter: /usr/libexec/platform-python
       when: virtualenv is defined
 
+    # If we gathered facts earlier it would have been with a different Python
+    # interpreter. For gathering modes that may use a fact cache, gather facts
+    # again using the interpreter from the virtual environment.
+    - name: Gather facts
+      setup:
+      when:
+        - virtualenv is defined
+        - gather_facts is not skipped
+        - lookup('config', 'DEFAULT_GATHERING') != 'implicit'
+
     - block:
         - name: Ensure Python setuptools and pip packages are installed
           vars:

ansible/kolla-target-venv.yml

@@ -21,7 +21,7 @@
     - block:
         - name: Gather facts
           setup:
-          when: ansible_python is not defined
+          when: not module_setup | default(false)
 
         - name: Ensure the Python virtualenv package is installed
           package:

ansible/network.yml

@@ -67,7 +67,6 @@
         {{ bond_interfaces |
            map('net_bond_obj') |
            list }}
-      become: True
 
 # Configure virtual ethernet patch links to connect the workload provision
 # and external network bridges to the Neutron OVS bridge.

ansible/roles/swift-rings/tasks/main.yml

@@ -9,6 +9,7 @@
     # Facts required for ansible_user_uid and ansible_user_gid.
     - name: Gather facts for swift ring build host
       setup:
+      when: not module_setup | default(false)
 
     - name: Ensure Swift ring build directory exists
       file:

releasenotes/notes/avoid-unconditional-fact-gathering-4dfbf96e2111ad51.yaml

@@ -0,0 +1,7 @@
+---
+upgrade:
+  - |
+    Avoids unnecessary fact gathering using the ``setup`` module. This should
+    improve the performance of environments using fact caching and the Ansible
+    ``smart`` fact gathering policy. See `story 2007492
+    <https://storyboard.openstack.org/#!/story/2007492>`__ for details.