Port allocation

The ports_manager library handles the low-level port allocation storage. It registers and stores UDP and TCP port information in a SQLite database for the local node within the cluster.

The SQLite database file, ports.sqlite, is stored in the node’s state/ directory. To inspect its contents, use the following command:

podman run -i --rm --volume /var/lib/nethserver/node/state/ports.sqlite:/srv/ports.sqlite:z alpine ash -c 'apk add sqlite ; sqlite3 /srv/ports.sqlite' <<<"SELECT *, 'tcp' FROM TCP_PORTS UNION SELECT *, 'udp' FROM UDP_PORTS;"

For more information, refer to Port allocation under the Modules section.

Importing the Library

To use the ports_manager library, you need to import it into your Python script as follows:

import node.ports_manager

Available Functions

allocate_ports

This function allows you to allocate a specific number of ports for a given module and protocol.

  • Parameters:
    • required_ports (int): The number of ports required.
    • module_name (str): The name of the module requesting the ports.
    • protocol (str): The protocol for which the ports are required (e.g. “tcp” or “udp”).

  • Return a tuple (start_port, end_port) if allocation is successful, None otherwise.

  • Usage Example:
allocated_ports = node.ports_manager.allocate_ports(5, "my_module", "tcp")
print(f"my_module ports allocated: {allocated_ports}")

deallocate_ports

This function allows you to deallocate all ports previously assigned to a specific module for a given protocol.

  • Parameters:
    • module_name (str): The name of the module for which ports should be deallocated.
    • protocol (str): The protocol for which the ports were allocated (e.g., “tcp” or “udp”).

  • Return a tuple (start_port, end_port) if deallocation is successful, None otherwise.

  • Usage Example:
deallocated_ports = node.ports_manager.deallocate_ports("my_module", "udp")
print(f"my_module ports deallocated: {deallocated_ports}")

Additional Notes

  • Ensure to handle exceptions that may be raised during the allocation or deallocation of ports.
  • Ports allocated will remain reserved for the specified module until they are explicitly deallocated.
  • When using the allocate_ports function, if the module already has allocated ports, they will first be deallocated and then reallocated.