package statemgr import ( "fmt" "github.com/hashicorp/terraform/states" "github.com/hashicorp/terraform/states/statefile" ) // PlannedStateUpdate is a special helper to obtain a statefile representation // of a not-yet-written state snapshot that can be written later by a call // to the companion function WritePlannedStateUpdate. // // The statefile object returned here has an unusual interpretation of its // metadata that is understood only by WritePlannedStateUpdate, and so the // returned object should not be used for any other purpose. // // If the state manager implements Locker then it is the caller's // responsibility to hold the lock at least for the duration of this call. // It is not safe to modify the given state concurrently while // PlannedStateUpdate is running. func PlannedStateUpdate(mgr Transient, planned *states.State) *statefile.File { ret := &statefile.File{ State: planned.DeepCopy(), } // If the given manager uses snapshot metadata then we'll save that // in our file so we can check it again during WritePlannedStateUpdate. if mr, ok := mgr.(PersistentMeta); ok { m := mr.StateSnapshotMeta() ret.Lineage = m.Lineage ret.Serial = m.Serial } return ret } // WritePlannedStateUpdate is a companion to PlannedStateUpdate that attempts // to apply a state update that was planned earlier to the given state // manager. // // An error is returned if this function detects that a new state snapshot // has been written to the backend since the update was planned, since that // invalidates the plan. An error is returned also if the manager itself // rejects the given state when asked to store it. // // If the returned error is nil, the given manager's transient state snapshot // is updated to match what was planned. It is the caller's responsibility // to then persist that state if the manager also implements Persistent and // the snapshot should be written to the persistent store. // // If the state manager implements Locker then it is the caller's // responsibility to hold the lock at least for the duration of this call. func WritePlannedStateUpdate(mgr Transient, planned *statefile.File) error { // If the given manager uses snapshot metadata then we'll check to make // sure no new snapshots have been created since we planned to write // the given state file. if mr, ok := mgr.(PersistentMeta); ok { m := mr.StateSnapshotMeta() if planned.Lineage != "" { if planned.Lineage != m.Lineage { return fmt.Errorf("planned state update is from an unrelated state lineage than the current state") } if planned.Serial != m.Serial { return fmt.Errorf("stored state has been changed by another operation since the given update was planned") } } } return mgr.WriteState(planned.State) }