Clone and restore apps with well-known ports

[DavidePrincipi]

Some applications (e.g., Mail, Dnsmasq, Ejabberd, Samba) are restricted to one instance per node because they bind to well-known TCP/UDP port numbers. While the Software Center enforces this limitation through the org.nethserver.max-per-node=1 label, the clone and restore procedures currently do not respect this label. As a result, these procedures may fail to start the services due to port conflicts.

Proposed Solution:
Ensure that the max-per-node label is honored during restore and clone operations. This would prevent conflicts for apps limited to specific ports. Note that this solution may not address conflicts between distinct modules (e.g., Samba and Dnsmasq), which could compete for the same port (DNS 53).

Alternative Solutions:

• Use the max-per-node label to issue a warning during the restore and clone process.
• Modify application behavior to avoid starting services if a port is already occupied. For example, Samba could skip startup if Dnsmasq is already running on port 53, or vice-versa.
• Provide detailed conflict reports to the user, including which applications or services are affected.

Additional context

N/A

See also

Discussions

• https://mattermost.nethesis.it/nethesis/pl/cifnncujkiymbxnnzgtm5u3xgo
• https://mattermost.nethesis.it/nethesis/pl/9ko5xmf7oidijxkhku18xdtrzr
• https://mattermost.nethesis.it/nethesis/pl/whrkm8y11trbz8ey64czwpgm9y

[DavidePrincipi]

Test case

With core 3.4.0-dev.1 the max-per-node limits are enforced during restore, clone and move workflows, completing the already existing enforcement of the install procedure.

For example I cannot clone/restore Mail on the same node. I cannot move Mail to another node, if there's another Mail instance already installed.

[nrauso]

test case: VERIFIED

[DavidePrincipi]

Released https://github.com/NethServer/ns8-core/releases/tag/3.4.0