Use get-pip script from repo release folder

This patch ensures that if the local repo server has a copy of the
get-pip.py script then it will be used instead of reaching out to
the default location on the internet.

The tasks to set upper constraints are removed form the unbound
and repo-server playbooks as those roles do not execute any form
of pip installation.

This approach is taken to ensure that:

- Before the repo is built, the get-pip process in the pip_install
  role still has two chances to fetch the get-pip.py script. If we
  simply override the first URL option in group_vars then the
  initial task will fail before the repo is built for the release
  being executed and we would therefore only get one fallback.

- After the repo is built, if the lxc-host-setup and other pre-repo
  playbooks are run, the plays will use the repo's get-pip script
  instead of reaching upstream to fetch a fresh one. This maintains
  a consistent get-pip script version within the same tag forever.
  If group_vars are set for the targets of these plays to use the
  upstream URL then the experience is not the same - the lxc_hosts
  group will always get the latest upstream get-pip script every
  time the playbook executes, resulting in the lxc hosts having a
  different copy of the script to other hosts and containers.

Partial-Bug: #1633105
Depends-On: I3735ec50d51e10d0bc4a7f6677a800444fb33912
Depends-On: I4a2ff6c6e5cd40d87d4218f63c09e96da82da1aa
Change-Id: I9b558a14e800bb77d78021f665173dcdfaf2f4aa

playbooks/common-tasks/set-pip-upstream-url.yml

@@ -0,0 +1,33 @@
+---
+# Copyright 2016, Rackspace US, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This set of tasks checks whether the repo is up yet. If it is it
+# will use the get-pip.py script available there. If it is not yet
+# up, then it will use the standard upstream get-pip.py script URL.
+
+- name: Test internal repo URL for the current get-pip.py script
+  uri:
+    url: "{{ pip_upstream_url }}"
+    method: "HEAD"
+  register: _repo_data_check
+  failed_when: false
+  when: pip_upstream_url != "https://bootstrap.pypa.io/get-pip.py"
+
+- name: Set pip upstream URL
+  set_fact:
+    pip_upstream_url: "https://bootstrap.pypa.io/get-pip.py"
+  when:
+    - pip_upstream_url != "https://bootstrap.pypa.io/get-pip.py"
+    - (_repo_data_check.status | default(503)) != 200

playbooks/inventory/group_vars/all.yml

@@ -49,6 +49,9 @@ pip_lock_to_internal_repo: "{{ (pip_links | length) >= 1 }}"
 # The upper constraints to apply to all pip installations
 pip_install_upper_constraints: "{{ openstack_repo_url }}/os-releases/{{ openstack_release }}/requirements_absolute_requirements.txt"
 
+# The URL to retrieve the get-pip.py installation script
+pip_upstream_url: "{{ (pip_offline_install | bool) | ternary('https://bootstrap.pypa.io/get-pip.py', openstack_repo_url ~ '/os-releases/' ~ openstack_release ~ '/get-pip.py') }}"
+
 ## OpenStack source options
 # URL for the frozen internal openstack repo.
 repo_server_port: 8181

playbooks/lxc-hosts-setup.yml

@@ -20,6 +20,7 @@
   user: root
   pre_tasks:
     - include: common-tasks/set-upper-constraints.yml
+    - include: common-tasks/set-pip-upstream-url.yml
     - name: Check the state of the default LXC service log directory
       stat:
         path: "/var/log/lxc"

playbooks/repo-build.yml

@@ -51,6 +51,7 @@
   pre_tasks:
 
     - include: common-tasks/set-upper-constraints.yml
+    - include: common-tasks/set-pip-upstream-url.yml
 
     - name: Load local packages
       debug:

playbooks/repo-server.yml

@@ -20,8 +20,6 @@
   user: root
   pre_tasks:
 
-    - include: common-tasks/set-upper-constraints.yml
-
     - name: Check if the git cache exists on deployment host
       local_action:
         module: stat

playbooks/unbound-install.yml

@@ -18,8 +18,6 @@
     - unbound_all
   gather_facts: "{{ gather_facts | default(True) }}"
   user: root
-  pre_tasks:
-    - include: common-tasks/set-upper-constraints.yml
   roles:
     - role: "unbound"
       tags: