[Bug]: Service stopped but not restarted when updating Debian package from 2.9.0 to 2.10.0

[smortex]

Describe the bug

When upgrading OpenSearch / OpenSearch Dashboards, the service is stopped by the prerm and not restarted by the postinst script.

To reproduce

Upgrade an existing install of OpenSearch / OpenSearch Dashboards

Expected behavior

Not starting the service on installation makes sense because the first start will bootstrap some config and data before the end-user had the opportunity to tune the system (e.g. change default admin password). While these changes can be made later, violating the Debian policy of starting services on installation makes sense in some cases like this one. I believe this behavior should be kept.

But if the OpenSearch service is running, it should be restarted during the update to minimize downtime.

Screenshots

No response

Host / Environment

Debian 11

Additional context

A similar behavior of not starting on install but restarting on upgrade is implemented in the following non-debian packages I install on my Debian nodes for configuration management: puppet & choria: both need some "seeding" before they can start.

The choria adjustments to have this behavior and match the Puppet one is in this PR:
choria-io/go-choria#1392

This might give some directions to add this to OpenSearch / OpenSearch Dashboards

Relevant log output

No response

[smortex]

Missed #3891. Will add the relevant info there.