Limit the number of app instances on the same node

[DavidePrincipi]

Applications with fixed port numbers like Mail and Ejabberd are limited to one instance per node, otherwise a port conflict arises at run time. The Software Center should limit the number of instances in the same node for such applications.

The limit may be observed also by the Clone/Move action, available from Software Center. However these advanced cases may prefer to allow a temporary conflict: it is a scenario that needs further evaluation.

Proposed solution

In the Install action, the Software Center prevents the selection of cluster nodes that already have an instance of the conflicting application.

Alternative solutions

The Software Center warns if a node is selected that already has a conflicting app instance.

Additional context

See also

• https://community.nethserver.org/t/ns8-community-suggestions-and-wishlist-please-feel-free-to-add/22442

[DavidePrincipi]

Test case

This feature can be tested once an application with label org.nethserver.max-per-node has been pushed to the app repository, e.g. Mail org.nethserver.max-per-node=1.

At that time, the Software Center prevents the installation of a second Mail instance into the same node.

[DavidePrincipi]

In testing:

• core 2.10.0-dev.1

[DavidePrincipi]

Released in https://github.com/NethServer/ns8-core/releases/tag/2.10.0