Add checks to docker role for 1.9.1+.

If Docker 1.8.2 is pre-installed, and no docker_version was requested,
role will now error out because 1.9.1 is required.

If docker_version is set to <= 1.9.1, we also error out as this is not
supported.

roles/docker/tasks/main.yml

@@ -4,10 +4,20 @@
 
 - name: Get current installed Docker version
   command: "{{ repoquery_cmd }} --installed --qf '%{version}' docker"
-  when:  docker_version is defined and not openshift.common.is_atomic | bool
+  when: not openshift.common.is_atomic | bool
   register: curr_docker_version
   changed_when: false
 
+- name: Error out if Docker pre-installed but too old
+  fail:
+    msg: "Docker {{ curr_docker_version.stdout }} is installed, but >= 1.9.1 is required."
+  when: not curr_docker_version | skipped and curr_docker_version.stdout != '' and curr_docker_version.stdout | version_compare('1.9.1', '<') and not docker_version is defined
+
+- name: Error out if requested Docker is too old
+  fail:
+    msg: "Docker {{ docker_version }} requested, but >= 1.9.1 is required."
+  when: docker_version is defined and docker_version | version_compare('1.9.1', '<')
+
 - name: Get latest available version of Docker
   command: >
     {{ repoquery_cmd }} --qf '%{version}' "docker"
@@ -21,14 +31,14 @@
 - name: Fail if Docker version requested but downgrade is required
   fail:
     msg: "Docker {{ curr_docker_version.stdout }} is installed, but version {{ docker_version }} was requested."
-  when: not curr_docker_version | skipped and curr_docker_version.stdout | default('0.0', True) | version_compare(docker_version, '>')
+  when: not curr_docker_version | skipped and curr_docker_version.stdout != '' and curr_docker_version.stdout | version_compare(docker_version, '>')
 
 # This involves an extremely slow migration process, users should instead run the
 # Docker 1.10 upgrade playbook to accomplish this.
 - name: Error out if attempting to upgrade Docker across the 1.10 boundary
   fail:
     msg: "Cannot upgrade Docker to >= 1.10, please use the Docker upgrade playbook for this."
-  when: not curr_docker_version | skipped and curr_docker_version.stdout | default('0.0', True) | version_compare('1.10', '<') and docker_version | version_compare('1.10', '>=')
+  when: not curr_docker_version | skipped and curr_docker_version.stdout != '' and curr_docker_version.stdout | version_compare('1.10', '<') and docker_version | version_compare('1.10', '>=')
 
 # Make sure Docker is installed, but does not update a running version.
 # Docker upgrades are handled by a separate playbook.