Use a common python build/install role

In order to radically simplify how we prepare the service
venvs, we use a common role to do the wheel builds and the
venv preparation. This makes the process far simpler to
understand, because the role does its own building and
installing. It also reduces the code maintenance burden,
because instead of duplicating the build processes in the
repo_build role and the service role - we only have it all
done in a single place.

We also change the role venv tag var to use the integrated
build's common venv tag so that we can remove the role's
venv tag in group_vars in the integrated build. This reduces
memory consumption and also reduces the duplication.

This is by no means the final stop in the simplification
process, but it is a step forward. The will be work to follow
which:

1. Replaces 'developer mode' with an equivalent mechanism
   that uses the common role and is simpler to understand.
   We will also simplify the provisioning of pip install
   arguments when doing this.
2. Simplifies the installation of optional pip packages.
   Right now it's more complicated than it needs to be due
   to us needing to keep the py_pkgs plugin working in the
   integrated build.
3. Deduplicates the distro package installs. Right now the
   role installs the distro packages twice - just before
   building the venv, and during the python_venv_build role
   execution.

Depends-On: https://review.openstack.org/598957
Change-Id: Ic00b23cb61ea7f0269d4e01b944d93accc3a218b
Implements: blueprint python-build-install-simplification
Signed-off-by: Jesse Pretorius <jesse.pretorius@rackspace.co.uk>

defaults/main.yml

@@ -27,8 +27,19 @@ monasca_agent_git_install_branch: master
 monasca_agent_developer_constraints:
   - "git+{{ monasca_agent_git_repo }}@{{ monasca_agent_git_install_branch }}#egg=monasca-agent"
 
+# TODO(odyssey4me):
+# This can be simplified once all the roles are using
+# python_venv_build. We can then switch to using a
+# set of constraints in pip.conf inside the venv,
+# perhaps prepared by giving a giving a list of
+# constraints to the role.
+monasca_agent_pip_install_args: >-
+  {{ monasca_agent_developer_mode | ternary(pip_install_developer_constraints | default('--constraint /opt/developer-pip-constraints.txt'), '') }}
+  {{ (pip_install_upper_constraints is defined) | ternary('--constraint ' + pip_install_upper_constraints | default(''), '') }}
+  {{ pip_install_options | default('') }}
+
 # Name of the virtual env to deploy into
-monasca_agent_venv_tag: untagged
+monasca_agent_venv_tag: "{{ venv_tag | default('untagged') }}"
 monasca_agent_bin: "/openstack/venvs/monasca-agent-{{ monasca_agent_venv_tag }}/bin"
 monasca_agent_etc_dir: "{{ monasca_agent_bin | dirname }}/etc/monasca/agent"
 

handlers/main.yml

@@ -19,5 +19,6 @@
     daemon_reload: "{{ (ansible_service_mgr == 'systemd') | ternary('yes', omit) }}"
   with_dict: "{{ monasca_agent_services }}"
   when: inventory_hostname in groups[item.value.group]
-
+  listen:
+    - "venv changed"
 

tasks/monasca_agent_install.yml

@@ -11,17 +11,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-- name: Install distro packages
-  package:
-    name: "{{ monasca_agent_distro_packages }}"
-    state: "{{ monasca_agent_package_state }}"
-    update_cache: "{{ (ansible_pkg_mgr in ['apt', 'zypper']) | ternary('yes', omit) }}"
-    cache_valid_time: "{{ (ansible_pkg_mgr == 'apt') | ternary(cache_timeout, omit) }}"
-  register: install_packages
-  until: install_packages is success
-  retries: 5
-  delay: 2
-
+# TODO(odyssey4me):
+# This can be simplified once all the roles are using
+# python_venv_build. We can then switch to using a
+# set of constraints in pip.conf inside the venv,
+# perhaps prepared by giving a giving a list of
+# constraints to the role.
 - name: Create developer mode constraint file
   copy:
     dest: "/opt/developer-pip-constraints.txt"
@@ -32,85 +27,22 @@
   when:
     - monasca_agent_developer_mode | bool
 
-- name: Retrieve checksum for venv download
-  uri:
-    url: "{{ monasca_agent_venv_download_url | replace('tgz', 'checksum') }}"
-    return_content: yes
-  register: monasca_agent_venv_checksum
-  when: monasca_agent_venv_download | bool
-
-- name: Attempt venv download
-  get_url:
-    url: "{{ monasca_agent_venv_download_url }}"
-    dest: "/var/cache/{{ monasca_agent_venv_download_url | basename }}"
-    checksum: "sha1:{{ monasca_agent_venv_checksum.content | trim }}"
-  register: monasca_agent_get_venv
-  when: monasca_agent_venv_download | bool
-
-- name: Remove existing venv
-  file:
-    path: "{{ monasca_agent_bin | dirname }}"
-    state: absent
-  when: monasca_agent_get_venv  is changed
-
-- name: Create monasca-agent venv dir
-  file:
-    path: "{{ monasca_agent_bin | dirname }}"
-    state: directory
-  register: monasca_agent_venv_dir
-  when: monasca_agent_get_venv  is changed
-
-- name: Unarchive pre-built venv
-  unarchive:
-    src: "/var/cache/{{ monasca_agent_venv_download_url | basename }}"
-    dest: "{{ monasca_agent_bin | dirname }}"
-    copy: "no"
-  when: monasca_agent_get_venv  is changed
-  notify:
-    - Restart monasca-agent services
-
-- name: Install pip packages
-  pip:
-    name: "{{ monasca_agent_pip_packages }}"
-    state: "{{ monasca_agent_pip_package_state }}"
-    virtualenv: "{{ monasca_agent_bin | dirname }}"
-    virtualenv_site_packages: "no"
-    extra_args: >-
-      {{ monasca_agent_developer_mode | ternary('--constraint /opt/developer-pip-constraints.txt', '') }}
-      {{ (pip_install_upper_constraints is defined) | ternary('--constraint ' + pip_install_upper_constraints | default(''),'') }}
-      {{ pip_install_options | default('') }}
-  register: install_packages
-  until: install_packages is success
-  retries: 5
-  delay: 2
-  when: monasca_agent_get_venv | failed or monasca_agent_get_venv | skipped
-  notify:
-    - Restart monasca-agent services
-
-- name: Remove python from path first (CentOS, openSUSE)
-  file:
-    path:  "{{ monasca_agent_bin | dirname }}/bin/python2.7"
-    state: "absent"
+- name: Ensure remote wheel building is disabled in developer mode
+  set_fact:
+    venv_build_host: "{{ ansible_hostname }}"
   when:
-    - ansible_pkg_mgr in ['yum', 'zypper']
-    - monasca_agent_get_venv  is changed
+    - monasca_agent_developer_mode | bool
 
-# NOTE(odyssey4me):
-# We reinitialize the venv to ensure that the right
-# version of python is in the venv, but we do not
-# want virtualenv to also replace pip, setuptools
-# and wheel so we tell it not to.
-# We do not use --always-copy for CentOS/SuSE due
-# to https://github.com/pypa/virtualenv/issues/565
-- name: Reset virtualenv and update its paths
-  shell: |
-    find {{ monasca_agent_bin }} -name \*.pyc -delete
-    sed -si '1s/^.*python.*$/#!{{ monasca_agent_bin | replace ('/','\/') }}\/python/' {{ monasca_agent_bin }}/*
-    virtualenv {{ monasca_agent_bin | dirname }} \
-        {{ (ansible_pkg_mgr == 'apt') | ternary('--always-copy', '') }} \
-        --no-pip \
-        --no-setuptools \
-        --no-wheel
-  when: monasca_agent_get_venv  is changed
-  tags:
-    - skip_ansible_lint
+- name: Install the python venv
+  include_role:
+    name: "python_venv_build"
+    private: yes
+  vars:
+    venv_install_destination_path: "{{ monasca_agent_bin | dirname }}"
+    venv_install_distro_package_list: "{{ monasca_agent_distro_packages }}"
+    venv_pip_install_args: "{{ monasca_agent_pip_install_args }}"
+    venv_pip_packages: "{{ monasca_agent_pip_packages }}"
+    venv_facts_when_changed:
+      - section: "monasca_agent"
+        option: "venv_tag"
+        value: "{{ monasca_agent_venv_tag }}"