Optimise pip install tasks

Unlike the Ansible apt module, the Ansible pip module does not
recognise a with_items list and process all the items at once.

To optimise the pip install tasks, this patch replaces the use
of with_items with a join filter so that the pip install task
does an install with all the packages in a list, ensuring that
the execution is one action instead of many.

Change-Id: I370c407fb77855fa5843d3ecbb608e94932e3447

tasks/swift_install.yml

@@ -65,14 +65,13 @@
 
 - name: Install requires pip packages
   pip:
-    name: "{{ item }}"
+    name: "{{ swift_requires_pip_packages | join(' ') }}"
     state: latest
     extra_args: "{{ pip_install_options_fact }}"
   register: install_packages
   until: install_packages|success
   retries: 5
   delay: 2
-  with_items: "{{ swift_requires_pip_packages }}"
   tags:
     - swift-install
     - swift-pip-packages
@@ -169,7 +168,7 @@
 
 - name: Install pip packages
   pip:
-    name: "{{ item }}"
+    name: "{{ swift_pip_packages | join(' ') }}"
     state: latest
     virtualenv: "{{ swift_bin | dirname }}"
     virtualenv_site_packages: "no"
@@ -178,7 +177,6 @@
   until: install_packages|success
   retries: 5
   delay: 2
-  with_items: "{{ swift_pip_packages }}"
   when:
     - not swift_pypy_enabled | bool
     - swift_get_venv | failed or swift_developer_mode | bool

tasks/swift_pypy_setup.yml

@@ -63,7 +63,7 @@
 
 - name: Install pip packages into pypy venv
   pip:
-    name: "{{ item }}"
+    name: "{{ swift_pip_packages | join(' ') }}"
     state: latest
     virtualenv: "{{ swift_bin | dirname }}"
     virtualenv_site_packages: "no"
@@ -73,7 +73,6 @@
   until: install_packages|success
   retries: 5
   delay: 2
-  with_items: "{{ swift_pip_packages }}"
   notify:
     - Restart swift account services
     - Restart swift container services