Allow pre-installed DLRN

https://review.openstack.org/498074 switched DLRN installation to
"pip install". However, it lost the ability to use a pre-installed
DLRN, which is useful for DLRN itself and used in a CI job to avoid
breaking TripleO with DLRN changes [1].

This change adds this option back, using a task variable
(dlrn_pre_installed, false by default).

[1] - https://softwarefactory-project.io/r/gitweb?p=config.git;a=blob;f=jobs-zuul/dlrn.yaml;h=21fd858b6b16ead6cd84850f2614fe3ee0f11f9f;hb=refs/heads/master#l113

Change-Id: Iee0d0cf3d7e3213aa14f91edd2e16afd3b3c8306

roles/build-test-packages/defaults/main.yml

@@ -8,6 +8,7 @@ artg_compressed_gating_repo: "/home/stack/gating_repo.tar.gz"
 dlrn_cleanup: false
 dlrn_baseurl: "https://trunk.rdoproject.org/centos7-{{ artg_release }}"
 dlrn_use_local_mirrors: false
+dlrn_pre_installed: false
 
 artg_skipped_projects:
   - openstack/puppet-openstack-integration

roles/build-test-packages/tasks/main.yml

@@ -30,6 +30,7 @@
   file:
     path: '{{ build_repo_dir }}/DLRN'
     state: absent
+  when: not dlrn_pre_installed|bool
 
 - name: Ensure DLRN dir is present
   file:
@@ -53,6 +54,16 @@
     name: dlrn
     virtualenv: "{{ build_repo_dir }}/dlrn-venv"
     state: latest
+  when: not dlrn_pre_installed|bool
+
+- name: Pip install pre-installed DLRN
+  shell: >
+    source {{ build_repo_dir }}/dlrn-venv/bin/activate;
+    pip install -r requirements.txt;
+    python setup.py install;
+  args:
+      chdir: '{{ build_repo_dir }}/DLRN'
+  when: dlrn_pre_installed|bool
 
 - name: copy the DLRN scripts in the virtualenv to the scripts dir
   shell: "/usr/bin/cp -Rv {{ build_repo_dir }}/dlrn-venv/share/dlrn/scripts {{ build_repo_dir }}/DLRN/"
@@ -159,6 +170,7 @@
     path: '{{ build_repo_dir }}/DLRN'
     state: absent
   when:
+    - not dlrn_pre_installed|bool
     - dlrn_cleanup|bool
 
 - name: Trigger repo injection for quickstart