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/set_docker_image_facts.yml

@@ -9,7 +9,7 @@
 
 - name: Register docker images info
   shell: >-
-    {{ docker_bin_dir }}/docker images -q | xargs {{ docker_bin_dir }}/docker inspect -f "{{ '{{' }} if .RepoTags {{ '}}' }}{{ '{{' }} (index .RepoTags 0) {{ '}}' }}{{ '{{' }} end {{ '}}' }}{{ '{{' }} if .RepoDigests {{ '}}' }},{{ '{{' }} (index .RepoDigests 0) {{ '}}' }}{{ '{{' }} end {{ '}}' }}" | tr '\n' ','
+    {{ docker_bin_dir }}/docker images -q | xargs -r {{ docker_bin_dir }}/docker inspect -f "{{ '{{' }} if .RepoTags {{ '}}' }}{{ '{{' }} (index .RepoTags) {{ '}}' }}{{ '{{' }} end {{ '}}' }}{{ '{{' }} if .RepoDigests {{ '}}' }},{{ '{{' }} (index .RepoDigests) {{ '}}' }}{{ '{{' }} end {{ '}}' }}" | sed -e 's/^ *\[//g' -e 's/\] *$//g' -e 's/ /\n/g' | tr '\n' ','
   no_log: true
   register: docker_images
   failed_when: false
@@ -22,6 +22,15 @@
       {%- if pull_args in docker_images.stdout.split(',') %}false{%- else -%}true{%- endif -%}
   when: not download_always_pull
 
+- name: Does any host require container pull?
+  vars:
+    hosts_pull_required: "{{ hostvars.values() | map(attribute='pull_required') | select('defined') | list }}"
+  set_fact:
+    any_pull_required: "{{ True in hosts_pull_required }}"
+  run_once: true
+  changed_when: false
+  when: not download_always_pull
+
 - name: Check the local digest sha256 corresponds to the given image tag
   assert:
     that: "{{download.repo}}:{{download.tag}} in docker_images.stdout.split(',')"