multiregion: deploymentwatcher hooks

This changeset establishes hooks in deploymentwatcher for multiregion
deployments (for the enterprise version of Nomad).

nomad/deployment_endpoint.go

@@ -112,7 +112,7 @@ func (d *Deployment) Fail(args *structs.DeploymentFailRequest, reply *structs.De
 	}
 
 	if !deploy.Active() {
-		return fmt.Errorf("can't fail terminal deployment")
+		return structs.ErrDeploymentTerminalNoFail
 	}
 
 	// Call into the deployment watcher
@@ -155,10 +155,10 @@ func (d *Deployment) Pause(args *structs.DeploymentPauseRequest, reply *structs.
 
 	if !deploy.Active() {
 		if args.Pause {
-			return fmt.Errorf("can't pause terminal deployment")
+			return structs.ErrDeploymentTerminalNoPause
 		}
 
-		return fmt.Errorf("can't resume terminal deployment")
+		return structs.ErrDeploymentTerminalNoResume
 	}
 
 	// Call into the deployment watcher
@@ -200,7 +200,7 @@ func (d *Deployment) Promote(args *structs.DeploymentPromoteRequest, reply *stru
 	}
 
 	if !deploy.Active() {
-		return fmt.Errorf("can't promote terminal deployment")
+		return structs.ErrDeploymentTerminalNoPromote
 	}
 
 	// Call into the deployment watcher
@@ -331,7 +331,7 @@ func (d *Deployment) SetAllocHealth(args *structs.DeploymentAllocHealthRequest,
 	}
 
 	if !deploy.Active() {
-		return fmt.Errorf("can't set health of allocations for a terminal deployment")
+		return structs.ErrDeploymentTerminalNoSetHealth
 	}
 
 	// Call into the deployment watcher

nomad/deploymentwatcher/deployment_watcher.go

@@ -62,6 +62,10 @@ type deploymentWatcher struct {
 	// deployment
 	deploymentTriggers
 
+	// multiregionTriggers holds the methods required to trigger
+	// changes on behalf of the deployment in enterprise edition
+	multiregionTriggers
+
 	// state is the state that is watched for state changes.
 	state *state.StateStore
 

nomad/deploymentwatcher/multiregion_oss.go

@@ -4,7 +4,11 @@ package deploymentwatcher
 
 import "github.com/hashicorp/nomad/nomad/structs"
 
-// TODO: move this into multiregion_oss.go once #269 is merged
+type multiregionTriggers interface{}
+
+func (w *deploymentWatcher) nextRegion(status string) error {
+	return nil
+}
 
 // UnblockDeployment is used to unblock a multiregion deployment.  In
 // single-region deployments, the blocked state is unused.

nomad/structs/errors.go

@@ -28,6 +28,15 @@ const (
 	ErrUnknownDeploymentPrefix = "Unknown deployment"
 
 	errRPCCodedErrorPrefix = "RPC Error:: "
+
+	errDeploymentTerminalNoCancel    = "can't cancel terminal deployment"
+	errDeploymentTerminalNoFail      = "can't fail terminal deployment"
+	errDeploymentTerminalNoPause     = "can't pause terminal deployment"
+	errDeploymentTerminalNoPromote   = "can't promote terminal deployment"
+	errDeploymentTerminalNoResume    = "can't resume terminal deployment"
+	errDeploymentTerminalNoUnblock   = "can't unblock terminal deployment"
+	errDeploymentTerminalNoSetHealth = "can't set health of allocations for a terminal deployment"
+	errDeploymentRunningNoUnblock    = "can't unblock running deployment"
 )
 
 var (
@@ -41,6 +50,15 @@ var (
 	ErrUnknownNomadVersion        = errors.New(errUnknownNomadVersion)
 	ErrNodeLacksRpc               = errors.New(errNodeLacksRpc)
 	ErrMissingAllocID             = errors.New(errMissingAllocID)
+
+	ErrDeploymentTerminalNoCancel    = errors.New(errDeploymentTerminalNoCancel)
+	ErrDeploymentTerminalNoFail      = errors.New(errDeploymentTerminalNoFail)
+	ErrDeploymentTerminalNoPause     = errors.New(errDeploymentTerminalNoPause)
+	ErrDeploymentTerminalNoPromote   = errors.New(errDeploymentTerminalNoPromote)
+	ErrDeploymentTerminalNoResume    = errors.New(errDeploymentTerminalNoResume)
+	ErrDeploymentTerminalNoUnblock   = errors.New(errDeploymentTerminalNoUnblock)
+	ErrDeploymentTerminalNoSetHealth = errors.New(errDeploymentTerminalNoSetHealth)
+	ErrDeploymentRunningNoUnblock    = errors.New(errDeploymentRunningNoUnblock)
 )
 
 // IsErrNoLeader returns whether the error is due to there being no leader.