Parameterize Ansible environment vars in Mistral Workflow

Add ansible_env_variables which a user may use to override
any Ansible environment variable. This new parameter is
then merged with the default env variables as set in
ansible_extra_env_variables.

Also adds DEFAULT_FORKS to the default env variables
with a new default of 50. Ansible automatically limits
the number of forks to the number of possible hosts at
runtime so it is not necessary to compute the fork count.

Change-Id: I5d69af146ca6ca8b3d5f78445cd1b47828daa955
Partial-Bug: 1738276

workbooks/ceph-ansible.yaml

@@ -9,6 +9,7 @@ workflows:
     input:
       - ansible_playbook_verbosity: 0
       - ansible_skip_tags: 'package-install,with_pkg'
+      - ansible_env_variables: {}
       - ansible_extra_env_variables:
           ANSIBLE_CONFIG: /usr/share/ceph-ansible/ansible.cfg
           ANSIBLE_ACTION_PLUGINS: /usr/share/ceph-ansible/plugins/actions/
@@ -18,6 +19,7 @@ workflows:
           ANSIBLE_LIBRARY: /usr/share/ceph-ansible/library/
           ANSIBLE_SSH_RETRIES: '3'
           ANSIBLE_HOST_KEY_CHECKING: 'False'
+          DEFAULT_FORKS: '50'
       - ceph_ansible_extra_vars: {}
       - ceph_ansible_playbook: /usr/share/ceph-ansible/site-docker.yml.sample
       - node_data_lookup: '{}'
@@ -54,10 +56,6 @@ workflows:
       merge_ip_lists:
         publish:
           ips_list: <% ($.mgr_ips + $.mon_ips + $.osd_ips + $.mds_ips + $.rgw_ips + $.nfs_ips + $.rbdmirror_ips + $.client_ips).toSet() %>
-        on-success: set_fork_count
-      set_fork_count:
-        publish:
-          fork_count: <% min($.ips_list.count(), 100) %> # don't use >100 forks
         on-success: make_fetch_directory
       make_fetch_directory:
         action: tripleo.files.make_temp_dir
@@ -143,10 +141,9 @@ workflows:
           become: true
           become_user: root
           verbosity: <% $.ansible_playbook_verbosity %>
-          forks: <% $.fork_count %>
           ssh_private_key: <% $.private_key %>
           skip_tags: <% $.ansible_skip_tags %>
-          extra_env_variables: <% $.ansible_extra_env_variables %>
+          extra_env_variables: <% $.ansible_extra_env_variables.mergeWith($.ansible_env_variables) %>
         publish:
           output: <% task().result %>
         on-complete: purge_fetch_directory