func openState(agentConfig agent.Config, dialOpts mongo.DialOpts) (_ *state.State, _ *state.Machine, err error) {
info, ok := agentConfig.MongoInfo()
if !ok {
return nil, nil, fmt.Errorf("no state info available")
}
st, err := state.Open(agentConfig.Model(), info, dialOpts, environs.NewStatePolicy())
if err != nil {
return nil, nil, err
}
defer func() {
if err != nil {
st.Close()
}
}()
m0, err := st.FindEntity(agentConfig.Tag())
if err != nil {
if errors.IsNotFound(err) {
err = worker.ErrTerminateAgent
}
return nil, nil, err
}
m := m0.(*state.Machine)
if m.Life() == state.Dead {
return nil, nil, worker.ErrTerminateAgent
}
// Check the machine nonce as provisioned matches the agent.Conf value.
if !m.CheckProvisioned(agentConfig.Nonce()) {
// The agent is running on a different machine to the one it
// should be according to state. It must stop immediately.
logger.Errorf("running machine %v agent on inappropriate instance", m)
return nil, nil, worker.ErrTerminateAgent
}
return st, m, nil
}