Verify openshift_image_tag is valid during openshift_version main

- origin examples: v1.2.3, v1.2.3-alpha, v1.2.3-beta.1, v1.5.0-rc.0
- openshift-enterprise examples: v3.5, v3.5.3, v3.5.3.4, v3.5.3.4-1

roles/openshift_version/tasks/main.yml

@@ -26,6 +26,37 @@
     openshift_release: "{{ openshift_release | string }}"
   when: openshift_release is defined
 
+# Verify that the image tag is in a valid format
+- block:
+
+  # Verifies that when the deployment type is origin the version:
+  # - starts with a v
+  # - Has 3 integers seperated by dots
+  # It also allows for optional trailing data which:
+  # - must start with a dash
+  # - may contain numbers, letters, dashes and dots.
+  - assert:
+      that:
+      - "{{ openshift_image_tag|match('(^v?\\d+\\.\\d+\\.\\d+(-[\\w\\-\\.]*)?$)') }}"
+      msg: "openshift_image_tag must be in the format v#.#.#[-optional.#]. Examples: v1.2.3, v3.5.1-alpha.1"
+    when: openshift.common.deployment_type == 'origin'
+
+  # Verifies that when the deployment type is openshift-enterprise the version:
+  # - starts with a v
+  # - Has at least 2 integers seperated by dots
+  # It also allows for optional trailing data which:
+  # - must start with a dash
+  # - may contain numbers
+  - assert:
+      that:
+      - "{{ openshift_image_tag|match('(^v\\d+\\.\\d+[\\.\\d+]*(-\\d+)?$)') }}"
+      msg: "openshift_image_tag must be in the format v#.#[.#[.#]]. Examples: v1.2, v3.4.1, v3.5.1.3, v1.2-1, v1.2.3-4"
+    when: openshift.common.deployment_type == 'openshift-enterprise'
+
+  when:
+  - openshift_image_tag is defined
+  - openshift_image_tag != "latest"
+
 # Add a v to the start of the openshift_image_tag if one was not provided
 - set_fact:
     openshift_image_tag: "{{ 'v' + openshift_image_tag }}"