import "github.com/juju/juju/instance" // create an instance with a specified app name and machine number ins := instance.NewInstance("myapp", 1)
import "github.com/juju/juju/cmd/envcmd" // get the hostname of the first machine of an application hostname, err := envcmd.GetMachineHostname(env, "myapp/0")
import "github.com/juju/juju/cmd/modelcmd" // set the constraints for the first machine of an application cmd := &modelcmd.UpdateMachineConstraintsCommand{} cmd.NewConstraints = "cpu-cores=2 mem=4G" err := cmd.UpdateMachineConstraints(env, "myapp/0")In summary, the Juju instance package is used for managing and orchestrating multiple application instances. Examples include creating an instance, getting the hostname of an instance, and setting constraints for an instance.