Enable delegating all downloads (binaries, images, kubeadm images) (#4420)

* Download to delegate and sync files when download_run_once

* Fail on error after saving container image

* Do not set changed status when downloaded container was up to date

* Only sync containers when they are actually required

Previously, non-required images (pull_required=false as
image existed on target host) were synced to the target
hosts. This failed as the image was not downloaded to
the download_delegate and hence was not available for
syncing.

* Sync containers when only missing on some hosts

* Consider images with multiple repo tags

* Enable kubeadm images pull/syncing with download_delegate

* Use kubeadm images list to pull/sync

'kubeadm config images pull' is replaced by collecting the images
list with 'kubeadm config images list' and using the commonly
used method of pull/syncing the images.

* Ensure containers are downloaded and synced for all hosts

* Fix download/syncing when download_delegate is a kubernetes host

roles/download/tasks/main.yml

@@ -3,31 +3,36 @@
   when:
     - not skip_downloads|default(false)
 
-- name: "Download items"
-  include_tasks: "{{ include_file }}"
-  vars:
-    download: "{{ download_defaults | combine(item.value) }}"
-    include_file: "download_{% if download.container %}container{% else %}file{% endif %}.yml"
-  with_dict: "{{ downloads }}"
-  when:
-    - not skip_downloads|default(false)
-    - item.value.enabled
-    - (not (item.value.container|default(False))) or (item.value.container and download_container)
-
-- name: "Sync container"
-  include_tasks: sync_container.yml
-  vars:
-    download: "{{ download_defaults | combine(item.value) }}"
-  with_dict: "{{ downloads }}"
-  when:
-    - not skip_downloads|default(false)
-    - item.value.enabled
-    - item.value.container | default(false)
-    - download_run_once
-    - group_names | intersect(download.groups) | length
-
 - include_tasks: kubeadm_images.yml
   when:
     - kube_version is version('v1.11.0', '>=')
     - not skip_downloads|default(false)
     - inventory_hostname in groups['kube-master']
+
+- set_fact:
+    kubeadm_images: {}
+  when:
+    - kubeadm_images is not defined
+
+- name: "Download items"
+  include_tasks: "{{ include_file }}"
+  vars:
+    download: "{{ download_defaults | combine(item.value) }}"
+    include_file: "download_{% if download.container %}container{% else %}file{% endif %}.yml"
+  with_dict: "{{ downloads | combine(kubeadm_images) }}"
+  when:
+    - not skip_downloads|default(false)
+    - item.value.enabled
+    - (not (item.value.container|default(False))) or (item.value.container and download_container)
+
+- name: "Sync items"
+  include_tasks: "{{ include_file }}"
+  vars:
+    download: "{{ download_defaults | combine(item.value) }}"
+    include_file: "sync_{% if download.container %}container{% else %}file{% endif %}.yml"
+  with_dict: "{{ downloads | combine(kubeadm_images) }}"
+  when:
+    - not skip_downloads|default(false)
+    - item.value.enabled
+    - download_run_once
+    - group_names | intersect(download.groups) | length