Limiting resources on a process

client/driver/plugins/executor_linux.go

@@ -14,12 +14,13 @@ import (
 	"time"
 
 	"github.com/hashicorp/go-multierror"
-	//"github.com/opencontainers/runc/libcontainer/cgroups"
-	//cgroupFs "github.com/opencontainers/runc/libcontainer/cgroups/fs"
-	//"github.com/opencontainers/runc/libcontainer/cgroups/systemd"
-	//cgroupConfig "github.com/opencontainers/runc/libcontainer/configs"
+	"github.com/opencontainers/runc/libcontainer/cgroups"
+	cgroupFs "github.com/opencontainers/runc/libcontainer/cgroups/fs"
+	"github.com/opencontainers/runc/libcontainer/cgroups/systemd"
+	cgroupConfig "github.com/opencontainers/runc/libcontainer/configs"
 
 	"github.com/hashicorp/nomad/client/allocdir"
+	"github.com/hashicorp/nomad/nomad/structs"
 )
 
 var (
@@ -41,7 +42,7 @@ type LinuxExecutor struct {
 	cmd exec.Cmd
 	ctx *ExecutorContext
 
-	//groups  *cgroupConfig.Cgroup
+	groups  *cgroupConfig.Cgroup
 	taskDir string
 
 	logger *log.Logger
@@ -86,10 +87,23 @@ func (e *LinuxExecutor) LaunchCmd(command *ExecCommand, ctx *ExecutorContext) (*
 
 	e.configureChroot()
 
+	if err := e.configureCgroups(e.ctx.Task.Resources); err != nil {
+		return nil, fmt.Errorf("error creating cgroups: %v", err)
+	}
+
 	if err := e.cmd.Start(); err != nil {
 		return nil, fmt.Errorf("error starting command: %v", err)
 	}
 
+	manager := e.getCgroupManager(e.groups)
+	if err := manager.Apply(e.cmd.Process.Pid); err != nil {
+		e.logger.Printf("[ERROR] unable to join cgroup: %v", err)
+		if err := e.Exit(); err != nil {
+			e.logger.Printf("[ERROR] unable to kill process: %v", err)
+		}
+		return nil, err
+	}
+
 	return &ProcessState{Pid: e.cmd.Process.Pid, ExitCode: -1, Time: time.Now()}, nil
 }
 
@@ -244,15 +258,18 @@ func (e *LinuxExecutor) Wait() (*ProcessState, error) {
 		}
 	}
 	e.cleanTaskDir()
+	e.destroyCgroup()
 	return &ProcessState{Pid: 0, ExitCode: exitCode, Time: time.Now()}, nil
 }
 
 func (e *LinuxExecutor) Exit() error {
+	e.logger.Printf("[INFO] Exiting plugin for task %q", e.ctx.Task.Name)
 	proc, err := os.FindProcess(e.cmd.Process.Pid)
 	if err != nil {
 		return fmt.Errorf("failied to find user process %v: %v", e.cmd.Process.Pid, err)
 	}
 	e.cleanTaskDir()
+	e.destroyCgroup()
 	return proc.Kill()
 }
 
@@ -266,3 +283,92 @@ func (e *LinuxExecutor) ShutDown() error {
 	}
 	return proc.Signal(os.Interrupt)
 }
+
+// configureCgroups converts a Nomad Resources specification into the equivalent
+// cgroup configuration. It returns an error if the resources are invalid.
+func (e *LinuxExecutor) configureCgroups(resources *structs.Resources) error {
+	e.groups = &cgroupConfig.Cgroup{}
+	e.groups.Resources = &cgroupConfig.Resources{}
+	e.groups.Name = structs.GenerateUUID()
+
+	// TODO: verify this is needed for things like network access
+	e.groups.Resources.AllowAllDevices = true
+
+	if resources.MemoryMB > 0 {
+		// Total amount of memory allowed to consume
+		e.groups.Resources.Memory = int64(resources.MemoryMB * 1024 * 1024)
+		// Disable swap to avoid issues on the machine
+		e.groups.Resources.MemorySwap = int64(-1)
+	}
+
+	if resources.CPU < 2 {
+		return fmt.Errorf("resources.CPU must be equal to or greater than 2: %v", resources.CPU)
+	}
+
+	// Set the relative CPU shares for this cgroup.
+	e.groups.Resources.CpuShares = int64(resources.CPU)
+
+	if resources.IOPS != 0 {
+		// Validate it is in an acceptable range.
+		if resources.IOPS < 10 || resources.IOPS > 1000 {
+			return fmt.Errorf("resources.IOPS must be between 10 and 1000: %d", resources.IOPS)
+		}
+
+		e.groups.Resources.BlkioWeight = uint16(resources.IOPS)
+	}
+
+	return nil
+}
+
+// destroyCgroup kills all processes in the cgroup and removes the cgroup
+// configuration from the host.
+func (e *LinuxExecutor) destroyCgroup() error {
+	if e.groups == nil {
+		return fmt.Errorf("Can't destroy: cgroup configuration empty")
+	}
+
+	// Prevent a race between Wait/ForceStop
+	e.lock.Lock()
+	defer e.lock.Unlock()
+
+	manager := e.getCgroupManager(e.groups)
+	pids, err := manager.GetPids()
+	if err != nil {
+		return fmt.Errorf("Failed to get pids in the cgroup %v: %v", e.groups.Name, err)
+	}
+
+	errs := new(multierror.Error)
+	for _, pid := range pids {
+		process, err := os.FindProcess(pid)
+		if err != nil {
+			multierror.Append(errs, fmt.Errorf("Failed to find Pid %v: %v", pid, err))
+			continue
+		}
+
+		if err := process.Kill(); err != nil && err.Error() != "os: process already finished" {
+			multierror.Append(errs, fmt.Errorf("Failed to kill Pid %v: %v", pid, err))
+			continue
+		}
+	}
+
+	// Remove the cgroup.
+	if err := manager.Destroy(); err != nil {
+		multierror.Append(errs, fmt.Errorf("Failed to delete the cgroup directories: %v", err))
+	}
+
+	if len(errs.Errors) != 0 {
+		return fmt.Errorf("Failed to destroy cgroup: %v", errs)
+	}
+
+	return nil
+}
+
+// getCgroupManager returns the correct libcontainer cgroup manager.
+func (e *LinuxExecutor) getCgroupManager(groups *cgroupConfig.Cgroup) cgroups.Manager {
+	var manager cgroups.Manager
+	manager = &cgroupFs.Manager{Cgroups: groups}
+	if systemd.UseSystemd() {
+		manager = &systemd.Manager{Cgroups: groups}
+	}
+	return manager
+}