private List<ApplicationContainer> createNodesFromNodeType(ApplicationContainerCluster cluster, Element nodesElement, ConfigModelContext context) {
        NodeType type = NodeType.valueOf(nodesElement.getAttribute("type"));
        ClusterSpec clusterSpec = ClusterSpec.request(ClusterSpec.Type.container, ClusterSpec.Id.from(cluster.getName()))
                .vespaVersion(context.getDeployState().getWantedNodeVespaVersion())
                .dockerImageRepository(context.getDeployState().getWantedDockerImageRepo())
                .build();
        Map<HostResource, ClusterMembership> hosts = 
                cluster.getRoot().hostSystem().allocateHosts(clusterSpec, Capacity.fromRequiredNodeType(type), deployLogger);
        return createNodesFromHosts(hosts, cluster, context.getDeployState());
    }
Allocate a container cluster without a nodes tag
config-model/src/main/java/com/yahoo/vespa/model/container/xml/ContainerModelBuilder.java