Try setting cache policy

.gitlab-ci-build.yml.in

@@ -11,6 +11,10 @@ stages:
           - sources/build.pkr.hcl
       paths:
         - ./packer_config/
+    - key: isofiles
+      paths:
+        - ./cache/*.iso
+      policy: pull
   rules:
     - if: $CI_COMMIT_TAG
       variables:
@@ -25,9 +29,6 @@ stages:
     - pipeline: $PARENT_PIPELINE_ID
       job: generate
       artifacts: true
-    - pipeline: $PARENT_PIPELINE_ID
-      job: download
-      artifacts: true
   tags:
     - ${tag}
   variables: &variables

.gitlab-ci.yml

@@ -63,15 +63,16 @@ shellcheck:
 downloads:
   stage: cache
   retry: 2
-  artifacts:
-    paths:
-      - cache/*.iso
   cache:
     - key:
         files:
           - sources/build.pkr.hcl
       paths:
         - ./packer_config/
+    - key: isofiles
+      paths:
+        - ./cache/*.iso
+      policy: push-pull
   script:
     - packer init sources
     - bash cache.sh