install-yarn: always install

The role previously conditionally installed YARN only if there was
a yarn.lock.  The role shouldn't conditionally decide to install
if there is a yarn.lock file as that's not expected behaviour.

Change-Id: Ia6940df036fd27d55d60fa959b794de952040745

roles/ensure-yarn/README.rst

@@ -1,13 +1 @@
 Install yarn from yarnpkg repos
-
-**Role Variables**
-
-.. zuul:rolevar:: zuul_work_dir
-   :default: {{ zuul.project.src_dir }}
-
-   The directory to work in.
-
-.. zuul:rolevar:: yarn_lock_file_path
-   :default: {{ zuul_work_dir }}/yarn.lock
-
-   Path to yarn.lock file used by a project.

roles/ensure-yarn/defaults/main.yaml

@@ -1,2 +0,0 @@
-zuul_work_dir: "{{ zuul.project.src_dir }}"
-yarn_lock_file_path: "{{ zuul_work_dir }}/yarn.lock"

roles/ensure-yarn/tasks/main.yaml

@@ -21,15 +21,14 @@
     repositories_keys: "{{ _yarn_keys | default([]) }}"
     repositories_list: "{{ _yarn_repos | default([]) }}"
 
-- name: Check for yarn.lock file
-  stat:
-    path: "{{ yarn_lock_file_path }}"
-    get_checksum: false
-    get_mime: false
-    get_md5: false
-  register: yarn_lock
+- name: Install yarn from yarnpkg.com
+  package:
+    name: yarn
+    state: latest
+  become: yes
+  tags:
+    # Ignore ANSIBLE0010: We really want latest version
+    - skip_ansible_lint
 
-- name: Install yarn if needed
-  include: yarn.yaml
-  when:
-    - yarn_lock.stat.exists
+- name: Output yarn version
+  command: yarn --version

roles/ensure-yarn/tasks/yarn.yaml

@@ -1,11 +0,0 @@
-- name: Install yarn from yarnpkg.com
-  package:
-    name: yarn
-    state: latest
-  become: yes
-  tags:
-    # Ignore ANSIBLE0010: We really want latest version
-    - skip_ansible_lint
-
-- name: Output yarn version
-  command: yarn --version