In 3scale 2.15 we migrated all components from DeploymentConfigs to Deployment. Deployment don't support lifecycle hooks we use Jobs as equivalent. 

However, with the current implementation, the operator will always run system-app-pre/post Job. This lead to the issue when the user scale down the APIManager 3scale version (2.15.3) by setting the replicas to 0 for the 3scale components, system-app-pre continues to run and reports the following error:

Errno::ECONNREFUSED: Connection denied - connect(2) for "backend-listener" port 3000.

The reason for this because we are reconciling the backend component first, so when system-app-pre runs the backend listener is already terminated.

Expected behaviour

To match previous 3scale behavior [1], scaling components should not trigger the system-app-pre/post hook

Workaround:

Keep the backend components running and scale down the system components first. Once all system components are terminated scale down backend components.

Reference:

[1] https://github.com/openshift/origin/blob/main/docs/proposals/post-deployment-hooks.md?plain=1