// commonServiceInstances returns instances with
// services in common with the specified machine.
func commonServiceInstances(st *state.State, m *state.Machine) ([]instance.Id, error) {
units, err := m.Units()
if err != nil {
return nil, err
}
var instanceIdSet set.Strings
for _, unit := range units {
if !unit.IsPrincipal() {
continue
}
service, err := unit.Service()
if err != nil {
return nil, err
}
allUnits, err := service.AllUnits()
if err != nil {
return nil, err
}
for _, unit := range allUnits {
machineId, err := unit.AssignedMachineId()
if state.IsNotAssigned(err) {
continue
} else if err != nil {
return nil, err
}
machine, err := st.Machine(machineId)
if err != nil {
return nil, err
}
instanceId, err := machine.InstanceId()
if err == nil {
instanceIdSet.Add(string(instanceId))
} else if state.IsNotProvisionedError(err) {
continue
} else {
return nil, err
}
}
}
instanceIds := make([]instance.Id, instanceIdSet.Size())
// Sort values to simplify testing.
for i, instanceId := range instanceIdSet.SortedValues() {
instanceIds[i] = instance.Id(instanceId)
}
return instanceIds, nil
}