fix: improve Docker image pull error handling and registry login

- Add debug output for image pull process
- Improve error handling: verify image exists after pull before tagging
- Fix registries_to_login Jinja2 template to handle undefined variables
- Add explicit failure if image pull fails
- Only tag image if it was successfully pulled

deployment/ansible/playbooks/deploy-image.yml

@@ -127,6 +127,15 @@
       ignore_errors: yes
       register: docker_login_result
 
+    - name: Display image pull information
+      ansible.builtin.debug:
+        msg:
+          - "Attempting to pull image: {{ deploy_image }}"
+          - "Source registry: {{ source_registry }}"
+          - "Local registry: {{ local_registry }}"
+          - "Registry accessible: {{ registry_accessible | default('unknown') }}"
+      when: registry_accessible is defined and registry_accessible == 'true'
+
     - name: Pull Docker image
       community.docker.docker_image:
         name: "{{ deploy_image }}"
@@ -137,11 +146,28 @@
       ignore_errors: yes
       failed_when: false
 
-    - name: Verify image exists locally
+    - name: Display pull result
+      ansible.builtin.debug:
+        msg:
+          - "Pull result: {{ image_pull_result | default('not executed') }}"
+          - "Pull failed: {{ image_pull_result.failed | default(false) }}"
+          - "Pull changed: {{ image_pull_result.changed | default(false) }}"
+      when: registry_accessible is defined and registry_accessible == 'true'
+
+    - name: Verify image exists locally after pull
       community.docker.docker_image_info:
         name: "{{ deploy_image }}"
       register: image_info
-      failed_when: image_info.failed | default(false)
+      when: registry_accessible is defined and registry_accessible == 'true'
+      ignore_errors: yes
+      failed_when: false
+
+    - name: Fail if image was not pulled successfully
+      ansible.builtin.fail:
+        msg: "Failed to pull image {{ deploy_image }} from registry. Image does not exist locally."
+      when: 
+        - registry_accessible is defined and registry_accessible == 'true'
+        - image_info.failed | default(true) | bool
 
     - name: Tag image for local registry (if source and local registry differ)
       community.docker.docker_image:
@@ -149,7 +175,9 @@
         repository: "{{ local_image }}"
         tag: "{{ image_tag }}"
         source: local
-      when: source_registry != local_registry
+      when: 
+        - source_registry != local_registry
+        - image_info.failed is not defined or not image_info.failed
       register: image_tag_result
 
     - name: Push image to local registry (if source and local registry differ)
@@ -277,10 +305,16 @@
     - name: Set list of registries to login to (source registry for pulling, local registry for pushing)
       ansible.builtin.set_fact:
         registries_to_login: >-
-          {%- set source_list = [source_registry] if source_registry != local_registry else [] -%}
-          {%- set local_list = [local_registry] -%}
-          {%- set all_registries = source_list + local_list -%}
-          {{ all_registries | unique | list }}
+          {%- if source_registry is defined and local_registry is defined -%}
+            {%- if source_registry != local_registry -%}
+              {%- set reg_list = [source_registry, local_registry] -%}
+            {%- else -%}
+              {%- set reg_list = [local_registry] -%}
+            {%- endif -%}
+            {{ reg_list | unique | list }}
+          {%- else -%}
+            {{ [docker_registry] }}
+          {%- endif -%}
 
     - name: Login to all Docker registries before compose up
       community.docker.docker_login: