[tmpnet] Update Network.CreateSubnets to require explicit node restart

tmpnet used to have working support for creating subnets after network
bootstrap. Subsequently, that code path has degraded due to subnet
creation only being performed as part of bootstrap to both speed up
suite setup and avoid disruptive node restart during test execution.

Rather than maintain the unused ability to create subnets
post-bootstrap, Network.CreateSubnets is updated to make explicit that
it is the requirement of the caller to restart nodes to reflect the
configuration of newly created subnets.

Author: maru-ava

tests/fixture/tmpnet/network.go

@@ -458,7 +458,7 @@ func (n *Network) Bootstrap(ctx context.Context, log logging.Logger) error {
 	}
 
 	// Don't restart the node during subnet creation since it will always be restarted afterwards.
-	if err := n.CreateSubnets(ctx, log, bootstrapNode, false /* restartRequired */); err != nil {
+	if err := n.CreateSubnets(ctx, log, bootstrapNode); err != nil {
 		return stacktrace.Wrap(err)
 	}
 
@@ -615,9 +615,9 @@ func (n *Network) GetSubnet(name string) *Subnet {
 	return nil
 }
 
-// Ensure that each subnet on the network is created. If restartRequired is false, node restart
-// to pick up configuration changes becomes the responsibility of the caller.
-func (n *Network) CreateSubnets(ctx context.Context, log logging.Logger, apiNode *Node, restartRequired bool) error {
+// Ensure that each subnet on the network is created. The caller is responsible for ensuring node
+// restart if required to ensure nodes read subnet configuration post-creation.
+func (n *Network) CreateSubnets(ctx context.Context, log logging.Logger, apiNode *Node) error {
 	createdSubnets := make([]*Subnet, 0, len(n.Subnets))
 	apiURI := apiNode.GetAccessibleURI()
 	for _, subnet := range n.Subnets {
@@ -674,41 +674,6 @@ func (n *Network) CreateSubnets(ctx context.Context, log logging.Logger, apiNode
 		return stacktrace.Wrap(err)
 	}
 
-	reconfiguredNodes := []*Node{}
-	for _, node := range n.Nodes {
-		existingTrackedSubnets := node.Flags[config.TrackSubnetsKey]
-		trackedSubnets := n.TrackedSubnetsForNode(node.NodeID)
-		if existingTrackedSubnets == trackedSubnets {
-			continue
-		}
-		node.Flags[config.TrackSubnetsKey] = trackedSubnets
-		reconfiguredNodes = append(reconfiguredNodes, node)
-	}
-
-	// TODO(samliok): remove the restart required parameter, and check if subnet configuration requires
-	// a restart instead.
-	if restartRequired {
-		log.Info("restarting node(s) to enable them to track the new subnet(s)")
-
-		runningNodes := make([]*Node, 0, len(reconfiguredNodes))
-		for _, node := range reconfiguredNodes {
-			if node.IsRunning() {
-				runningNodes = append(runningNodes, node)
-			}
-		}
-
-		if err := restartNodes(ctx, runningNodes); err != nil {
-			return stacktrace.Wrap(err)
-		}
-
-		if err := WaitForHealthyNodes(ctx, n.log, runningNodes); err != nil {
-			return stacktrace.Wrap(err)
-		}
-
-		// since we have restarted nodes, refetch the api uri in case it changed
-		apiURI = apiNode.GetAccessibleURI()
-	}
-
 	// Add validators for the subnet
 	for _, subnet := range createdSubnets {
 		log.Info("adding validators for subnet",
@@ -760,7 +725,7 @@ func (n *Network) CreateSubnets(ctx context.Context, log logging.Logger, apiNode
 		}
 	}
 
-	if !restartRequired || len(validatorsToRestart) == 0 {
+	if len(validatorsToRestart) == 0 {
 		return nil
 	}