How to create a persistent network using libvirt-java

Question

I would like to create a network with both persistent and autostart flags set using libvirt-java:

Connect connect = new Connect("qemu:///system", false);
Network network = connect.networkCreateXML("""
        <network>
          <name>foo</name>
          <forward mode='nat'>
            <nat>
              <port start='1024' end='65535'/>
            </nat>
          </forward>
          <bridge name='virfoo' stp='on' delay='0'/>
          <ip address='192.168.99.1' netmask='255.255.255.0'/>
        </network>
        """);
network.setAutostart(true);

When executing network.setAutostart(true) the following error is thrown:

libvirt: Network Driver error : Requested operation is not valid: cannot set autostart for transient network

virsh net-list --all on command line shows:

Name      State    Autostart   Persistent
--------------------------------------------
 default   active   yes         yes
 foo       active   no          no

How can I create or update the network as persistent using libvirt-java?

I can see that there is a method network.isPersistent(). But where can I set that flag?

Answer 1

The API follows the same conventions as the command line: create methods (like virsh net-create) create transient resources; to create persistent resources, you need to use the define alternative (like virsh net-define):

Network network = connect.networkDefineXML("""
    <network>
    <name>foo</name>
    <forward mode='nat'>
    <nat>
    <port start='1024' end='65535'/>
    </nat>
    </forward>
    <bridge name='virfoo' stp='on' delay='0'/>
    <ip address='192.168.99.1' netmask='255.255.255.0'/>
    </network>
    """);
network.create();
network.setAutostart(true);

Note that when you define something, it will create the persistent resource but will not start it; that's why we need that extra call to network.create().

The result of running the above code is:

$ virsh net-list
 Name      State    Autostart   Persistent
--------------------------------------------
 default   active   yes         yes
 foo       active   yes         yes