[#3896cn] Add support for suspending a server and blocking boot when suspended

server/environment_docker.go

@@ -215,6 +215,16 @@ func (d *DockerEnvironment) Start() error {
 		}
 	}()
 
+	// If the server is suspended the user shouldn't be able to boot it, in those cases
+	// return a suspension error and let the calling area handle the issue.
+	//
+	// Theoretically you'd have the Panel handle all of this logic, but we cannot do that
+	// because we allow the websocket to control the server power state as well, so we'll
+	// need to handle that action in here.
+	if d.Server.Suspended {
+		return &suspendedError{}
+	}
+
 	c, err := d.Client.ContainerInspect(context.Background(), d.Server.Uuid)
 	if err != nil && !client.IsErrNotFound(err) {
 		return errors.WithStack(err)

server/errors.go

@@ -0,0 +1,14 @@
+package server
+
+type suspendedError struct {
+}
+
+func (e *suspendedError) Error() string {
+	return "server is currently in a suspended state"
+}
+
+func IsSuspendedError(err error) bool {
+	_, ok := err.(*suspendedError)
+
+	return ok
+}

server/update.go

@@ -5,6 +5,8 @@ import (
 	"github.com/buger/jsonparser"
 	"github.com/imdario/mergo"
 	"github.com/pkg/errors"
+	"go.uber.org/zap"
+	"os"
 )
 
 // Merges data passed through in JSON form into the existing server object.
@@ -59,5 +61,41 @@ func (s *Server) UpdateDataStructure(data []byte) error {
 		return errors.WithStack(err)
 	}
 
-	return s.Environment.InSituUpdate()
+	s.runBackgroundActions()
+
+	return nil
+}
+
+// Runs through different actions once a server's configuration has been persisted
+// to the disk. This function does not return anything as any failures should be logged
+// but have no effect on actually updating the server itself.
+//
+// These tasks run in independent threads where relevant to speed up any updates
+// that need to happen.
+func (s *Server) runBackgroundActions() {
+	// Update the environment in place, allowing memory and CPU usage to be adjusted
+	// on the fly without the user needing to reboot (theoretically).
+	go func(server *Server) {
+		if err := server.Environment.InSituUpdate(); err != nil {
+			zap.S().Warnw(
+				"failed to perform in-situ update of server environment",
+				zap.String("server", server.Uuid),
+				zap.Error(err),
+			)
+		}
+	}(s)
+
+	// Check if the server is now suspended, and if so and the process is not terminated
+	// yet, do it immediately.
+	go func(server *Server) {
+		if server.Suspended && server.State != ProcessOfflineState {
+			if err := server.Environment.Terminate(os.Kill); err != nil {
+				zap.S().Warnw(
+					"failed to terminate server environment after seeing suspension",
+					zap.String("server", server.Uuid),
+					zap.Error(err),
+				)
+			}
+		}
+	}(s)
 }