Fix plan json generation if `warning_on_non_empty_plan` is `true` and plan is non-empty

Closes https://gitlab.com/components/opentofu/-/issues/81

Changelog: fixed

src/gitlab-tofu.sh

@@ -244,12 +244,23 @@ if [ $sourced -eq 0 ]; then
 
       $TF_IMPLICIT_INIT && terraform_init
       # shellcheck disable=SC2086
-      tofu "${TF_CHDIR_OPT}" "${@}" -input=false -out="${TF_PLAN_CACHE}" ${var_file_args} ${plan_args}
+      tofu "${TF_CHDIR_OPT}" "${@}" -input=false -out="${TF_PLAN_CACHE}" ${var_file_args} ${plan_args} && ret=$? || ret=$?
+
+      if [ "${OPENTOFU_COMPONENT_PLAN_WITH_JSON}" = 'true' ]; then
+        if [ "$ret" -eq 0 ] || [ "$ret" -eq 2 ]; then
+          if ! tofu "${TF_CHDIR_OPT}" show -json "${TF_PLAN_CACHE}" | jq -r "${JQ_PLAN}" > "${TF_PLAN_JSON}"; then
+            exit $?
+          fi
+
+          # NOTE: we want to exit with the tofu plan exit code if the tofu show command call is successful.
+          exit "$ret"
+        fi
+      fi
+
+      exit "$ret"
     ;;
     "plan-json")
-      tofu "${TF_CHDIR_OPT}" show -json "${TF_PLAN_CACHE}" | \
-        jq -r "${JQ_PLAN}" \
-        > "${TF_PLAN_JSON}"
+      tofu "${TF_CHDIR_OPT}" show -json "${TF_PLAN_CACHE}" | jq -r "${JQ_PLAN}" > "${TF_PLAN_JSON}"
     ;;
     "validate")
       $TF_IMPLICIT_INIT && terraform_init -backend=false

templates/plan.yml

@@ -120,6 +120,11 @@ spec:
     # NOTE: tofu plan -detailed-exitcode return 2 as exit code
     # when the plan is non-empty.
     exit_codes: [2]
+  artifacts:
+    # NOTE: we require to always upload artifacts, because when `warning_on_non_empty_plan` is set enabled
+    # and there is a non-empty plan we have an exit code of `2` which is considered a (failure),
+    # but we still want to upload all the artifacts.
+    when: always
 
 '$[[ inputs.as ]]':
   stage: $[[ inputs.stage ]]
@@ -152,10 +157,10 @@ spec:
     TF_ROOT: $[[ inputs.root_dir ]]
     TF_STATE_NAME: $[[ inputs.state_name ]]
     TF_PLAN_NAME: $[[ inputs.plan_name ]]
+    OPENTOFU_COMPONENT_PLAN_WITH_JSON: true
     OPENTOFU_COMPONENT_VAR_FILE: '$[[ inputs.var_file ]]'
   image:
     name: '$[[ inputs.image_registry_base ]]/$[[ inputs.image_name ]]:$[[ inputs.version ]]-opentofu$[[ inputs.opentofu_version ]]-$[[ inputs.base_os ]]$[[ inputs.image_digest ]]'
   script:
     - "args=\"\"\nif [ \"$[[ inputs.destroy ]]\" == \"true\" ]; then \n  echo \"Planning for a destroy\"\n  args=\"-destroy\"\nfi\n"
     - gitlab-tofu plan $args
-    - gitlab-tofu plan-json