Implement review comments

api/swagger.yaml

@@ -188,10 +188,6 @@ paths:
                   description: Specifies the execution environment of the runner
                   type: integer
                   example: 6
-                useAWS:
-                  description: Should Poseidon use AWS for the execution.
-                  type: boolean
-                  default: false
               required:
                 - executionEnvironmentId
               additionalProperties: false

configuration.example.yaml

@@ -48,7 +48,7 @@ aws:
   enabled: false
   # The enpoint of the WebSocket API
   endpoint: wss://abcdef1234.execute-api.eu-central-1.amazonaws.com/production
-  # Currently, only static AWS environments are supported. You can list them here.
+  # Currently, only static AWS environments are supported. You can list them here separated by spaces.
   functions: "java11Exec go118Exec"
 
 # Configuration of the logger

internal/environment/abstract_manager.go

@@ -1,6 +1,7 @@
 package environment
 
 import (
+	"fmt"
 	"github.com/openHPI/poseidon/internal/runner"
 	"github.com/openHPI/poseidon/pkg/dto"
 )
@@ -8,7 +9,8 @@ import (
 // AbstractManager is used to have a fallback environment manager in the chain of responsibility
 // following the null object pattern.
 type AbstractManager struct {
-	nextHandler ManagerHandler
+	nextHandler   ManagerHandler
+	runnerManager runner.Manager
 }
 
 func (n *AbstractManager) SetNextHandler(next ManagerHandler) {
@@ -35,8 +37,25 @@ func (n *AbstractManager) CreateOrUpdate(_ dto.EnvironmentID, _ dto.ExecutionEnv
 	return false, nil
 }
 
-func (n *AbstractManager) Delete(_ dto.EnvironmentID) (bool, error) {
+func (n *AbstractManager) Delete(id dto.EnvironmentID) (bool, error) {
-	return false, nil
+	e, ok := n.runnerManager.GetEnvironment(id)
+	if !ok {
+		if n.nextHandler != nil {
+			isFound, err := n.NextHandler().Delete(id)
+			if err != nil {
+				return false, fmt.Errorf("aws wrapped: %w", err)
+			}
+			return isFound, nil
+		} else {
+			return false, nil
+		}
+	}
+
+	n.runnerManager.DeleteEnvironment(id)
+	if err := e.Delete(); err != nil {
+		return true, fmt.Errorf("could not delete environment: %w", err)
+	}
+	return true, nil
 }
 
 func (n *AbstractManager) Statistics() map[dto.EnvironmentID]*dto.StatisticalExecutionEnvironmentData {

internal/environment/aws_environment.go

@@ -36,31 +36,6 @@ func (a *AWSEnvironment) SetID(id dto.EnvironmentID) {
 	a.id = id
 }
 
-func (a *AWSEnvironment) PrewarmingPoolSize() uint {
-	return 0
-}
-
-func (a *AWSEnvironment) SetPrewarmingPoolSize(_ uint) {}
-
-func (a *AWSEnvironment) ApplyPrewarmingPoolSize() error {
-	return nil
-}
-
-func (a *AWSEnvironment) CPULimit() uint {
-	return 0
-}
-
-// SetCPULimit is disabled as one can only set the memory limit with AWS Lambda.
-func (a *AWSEnvironment) SetCPULimit(_ uint) {}
-
-func (a *AWSEnvironment) MemoryLimit() uint {
-	panic("implement me")
-}
-
-func (a *AWSEnvironment) SetMemoryLimit(_ uint) {
-	panic("implement me")
-}
-
 // Image is used to specify the AWS Endpoint Poseidon is connecting to.
 func (a *AWSEnvironment) Image() string {
 	return a.awsEndpoint
@@ -70,22 +45,6 @@ func (a *AWSEnvironment) SetImage(awsEndpoint string) {
 	a.awsEndpoint = awsEndpoint
 }
 
-func (a *AWSEnvironment) NetworkAccess() (enabled bool, mappedPorts []uint16) {
-	panic("implement me")
-}
-
-func (a *AWSEnvironment) SetNetworkAccess(_ bool, _ []uint16) {
-	panic("implement me")
-}
-
-func (a *AWSEnvironment) SetConfigFrom(_ runner.ExecutionEnvironment) {
-	panic("implement me")
-}
-
-func (a *AWSEnvironment) Register() error {
-	panic("implement me")
-}
-
 func (a *AWSEnvironment) Delete() error {
 	return nil
 }
@@ -98,14 +57,61 @@ func (a *AWSEnvironment) Sample() (r runner.Runner, ok bool) {
 	return workload, true
 }
 
+// The following methods are not supported at this moment.
+
+// PrewarmingPoolSize is neither supported nor required. It is handled transparently by AWS.
+func (a *AWSEnvironment) PrewarmingPoolSize() uint {
+	return 0
+}
+
+// SetPrewarmingPoolSize is neither supported nor required. It is handled transparently by AWS.
+func (a *AWSEnvironment) SetPrewarmingPoolSize(_ uint) {}
+
+// ApplyPrewarmingPoolSize is neither supported nor required. It is handled transparently by AWS.
+func (a *AWSEnvironment) ApplyPrewarmingPoolSize() error {
+	return nil
+}
+
+// CPULimit is disabled as one can only set the memory limit with AWS Lambda.
+func (a *AWSEnvironment) CPULimit() uint {
+	return 0
+}
+
+// SetCPULimit is disabled as one can only set the memory limit with AWS Lambda.
+func (a *AWSEnvironment) SetCPULimit(_ uint) {}
+
+func (a *AWSEnvironment) MemoryLimit() uint {
+	panic("not supported")
+}
+
+func (a *AWSEnvironment) SetMemoryLimit(_ uint) {
+	panic("not supported")
+}
+
+func (a *AWSEnvironment) NetworkAccess() (enabled bool, mappedPorts []uint16) {
+	panic("not supported")
+}
+
+func (a *AWSEnvironment) SetNetworkAccess(_ bool, _ []uint16) {
+	panic("not supported")
+}
+
+func (a *AWSEnvironment) SetConfigFrom(_ runner.ExecutionEnvironment) {
+	panic("not supported")
+}
+
+func (a *AWSEnvironment) Register() error {
+	panic("not supported")
+}
+
 func (a *AWSEnvironment) AddRunner(_ runner.Runner) {
-	panic("implement me")
+	panic("not supported")
 }
 
 func (a *AWSEnvironment) DeleteRunner(_ string) {
-	panic("implement me")
+	panic("not supported")
 }
 
 func (a *AWSEnvironment) IdleRunnerCount() int {
-	panic("implement me")
+	panic("not supported")
 }

internal/environment/aws_manager.go

@@ -12,11 +12,10 @@ import (
 // IMPROVE: Create Lambda functions dynamically.
 type AWSEnvironmentManager struct {
 	*AbstractManager
-	runnerManager runner.Manager
 }
 
 func NewAWSEnvironmentManager(runnerManager runner.Manager) *AWSEnvironmentManager {
-	m := &AWSEnvironmentManager{&AbstractManager{nil}, runnerManager}
+	m := &AWSEnvironmentManager{&AbstractManager{nil, runnerManager}}
 	runnerManager.Load()
 	return m
 }
@@ -69,23 +68,6 @@ func isAWSEnvironment(request dto.ExecutionEnvironmentRequest) bool {
 	return false
 }
 
-func (a *AWSEnvironmentManager) Delete(id dto.EnvironmentID) (bool, error) {
-	e, ok := a.runnerManager.GetEnvironment(id)
-	if !ok {
-		isFound, err := a.NextHandler().Delete(id)
-		if err != nil {
-			return false, fmt.Errorf("aws wrapped: %w", err)
-		}
-		return isFound, nil
-	}
-
-	a.runnerManager.DeleteEnvironment(id)
-	if err := e.Delete(); err != nil {
-		return true, fmt.Errorf("could not delete environment: %w", err)
-	}
-	return true, nil
-}
-
 func (a *AWSEnvironmentManager) Statistics() map[dto.EnvironmentID]*dto.StatisticalExecutionEnvironmentData {
 	return a.NextHandler().Statistics()
 }

internal/environment/aws_manager_test.go

@@ -28,7 +28,7 @@ func TestAWSEnvironmentManager_CreateOrUpdate(t *testing.T) {
 		assert.Equal(t, environment.Image(), uniqueImage)
 	})
 
-	t.Run("non handleable requests are forwarded to the next manager", func(t *testing.T) {
+	t.Run("non-handleable requests are forwarded to the next manager", func(t *testing.T) {
 		nextHandler := &ManagerHandlerMock{}
 		nextHandler.On("CreateOrUpdate", mock.AnythingOfType("dto.EnvironmentID"),
 			mock.AnythingOfType("dto.ExecutionEnvironmentRequest")).Return(true, nil)
@@ -58,7 +58,7 @@ func TestAWSEnvironmentManager_Get(t *testing.T) {
 	})
 
 	t.Run("Returns error when not found", func(t *testing.T) {
-		nextHandler := &AbstractManager{nil}
+		nextHandler := &AbstractManager{nil, nil}
 		m.SetNextHandler(nextHandler)
 
 		_, err := m.Get(tests.DefaultEnvironmentIDAsInteger, false)
@@ -80,7 +80,7 @@ func TestAWSEnvironmentManager_List(t *testing.T) {
 	runnerManager := runner.NewAWSRunnerManager()
 	m := NewAWSEnvironmentManager(runnerManager)
 
-	t.Run("returs also environments of the rest of the manager chain", func(t *testing.T) {
+	t.Run("also returns environments of the rest of the manager chain", func(t *testing.T) {
 		nextHandler := &ManagerHandlerMock{}
 		existingEnvironment := NewAWSEnvironment(nil)
 		nextHandler.On("List", mock.AnythingOfType("bool")).

internal/environment/nomad_environment.go

@@ -22,10 +22,10 @@ const (
 var ErrScaleDown = errors.New("cannot scale down the environment")
 
 type NomadEnvironment struct {
+	apiClient   nomad.ExecutorAPI
 	jobHCL      string
 	job         *nomadApi.Job
 	idleRunners runner.Storage
-	apiClient   nomad.ExecutorAPI
 }
 
 func NewNomadEnvironment(apiClient nomad.ExecutorAPI, jobHCL string) (*NomadEnvironment, error) {
@@ -34,7 +34,7 @@ func NewNomadEnvironment(apiClient nomad.ExecutorAPI, jobHCL string) (*NomadEnvi
 		return nil, fmt.Errorf("error parsing Nomad job: %w", err)
 	}
 
-	return &NomadEnvironment{jobHCL, job, runner.NewLocalRunnerStorage(), apiClient}, nil
+	return &NomadEnvironment{apiClient, jobHCL, job, runner.NewLocalRunnerStorage()}, nil
 }
 
 func NewNomadEnvironmentFromRequest(
@@ -252,7 +252,7 @@ func (n *NomadEnvironment) IdleRunnerCount() int {
 }
 
 // MarshalJSON implements the json.Marshaler interface.
-// This converts the AWSEnvironment into the expected schema for dto.ExecutionEnvironmentData.
+// This converts the NomadEnvironment into the expected schema for dto.ExecutionEnvironmentData.
 func (n *NomadEnvironment) MarshalJSON() (res []byte, err error) {
 	networkAccess, exposedPorts := n.NetworkAccess()
 

internal/environment/nomad_environment_test.go

@@ -17,7 +17,7 @@ import (
 func TestConfigureNetworkCreatesNewNetworkWhenNoNetworkExists(t *testing.T) {
 	_, job := helpers.CreateTemplateJob()
 	defaultTaskGroup := nomad.FindAndValidateDefaultTaskGroup(job)
-	environment := &NomadEnvironment{"", job, nil, nil}
+	environment := &NomadEnvironment{nil, "", job, nil}
 
 	if assert.Equal(t, 0, len(defaultTaskGroup.Networks)) {
 		environment.SetNetworkAccess(true, []uint16{})
@@ -29,7 +29,7 @@ func TestConfigureNetworkCreatesNewNetworkWhenNoNetworkExists(t *testing.T) {
 func TestConfigureNetworkDoesNotCreateNewNetworkWhenNetworkExists(t *testing.T) {
 	_, job := helpers.CreateTemplateJob()
 	defaultTaskGroup := nomad.FindAndValidateDefaultTaskGroup(job)
-	environment := &NomadEnvironment{"", job, nil, nil}
+	environment := &NomadEnvironment{nil, "", job, nil}
 
 	networkResource := &nomadApi.NetworkResource{Mode: "bridge"}
 	defaultTaskGroup.Networks = []*nomadApi.NetworkResource{networkResource}
@@ -58,7 +58,7 @@ func TestConfigureNetworkSetsCorrectValues(t *testing.T) {
 			_, testJob := helpers.CreateTemplateJob()
 			testTaskGroup := nomad.FindAndValidateDefaultTaskGroup(testJob)
 			testTask := nomad.FindAndValidateDefaultTask(testTaskGroup)
-			testEnvironment := &NomadEnvironment{"", job, nil, nil}
+			testEnvironment := &NomadEnvironment{nil, "", job, nil}
 
 			testEnvironment.SetNetworkAccess(false, ports)
 			mode, ok := testTask.Config["network_mode"]
@@ -73,7 +73,7 @@ func TestConfigureNetworkSetsCorrectValues(t *testing.T) {
 			_, testJob := helpers.CreateTemplateJob()
 			testTaskGroup := nomad.FindAndValidateDefaultTaskGroup(testJob)
 			testTask := nomad.FindAndValidateDefaultTask(testTaskGroup)
-			testEnvironment := &NomadEnvironment{"", testJob, nil, nil}
+			testEnvironment := &NomadEnvironment{nil, "", testJob, nil}
 
 			testEnvironment.SetNetworkAccess(true, ports)
 			require.Equal(t, 1, len(testTaskGroup.Networks))
@@ -113,7 +113,7 @@ func TestRegisterFailsWhenNomadJobRegistrationFails(t *testing.T) {
 	apiClientMock.On("LoadRunnerIDs", mock.AnythingOfType("string")).Return([]string{}, nil)
 	apiClientMock.On("DeleteJob", mock.AnythingOfType("string")).Return(nil)
 
-	environment := &NomadEnvironment{"", &nomadApi.Job{}, runner.NewLocalRunnerStorage(), apiClientMock}
+	environment := &NomadEnvironment{apiClientMock, "", &nomadApi.Job{}, runner.NewLocalRunnerStorage()}
 	environment.SetID(tests.DefaultEnvironmentIDAsInteger)
 	err := environment.Register()
 
@@ -130,7 +130,7 @@ func TestRegisterTemplateJobSucceedsWhenMonitoringEvaluationSucceeds(t *testing.
 	apiClientMock.On("LoadRunnerIDs", mock.AnythingOfType("string")).Return([]string{}, nil)
 	apiClientMock.On("DeleteJob", mock.AnythingOfType("string")).Return(nil)
 
-	environment := &NomadEnvironment{"", &nomadApi.Job{}, runner.NewLocalRunnerStorage(), apiClientMock}
+	environment := &NomadEnvironment{apiClientMock, "", &nomadApi.Job{}, runner.NewLocalRunnerStorage()}
 	environment.SetID(tests.DefaultEnvironmentIDAsInteger)
 	err := environment.Register()
 
@@ -146,7 +146,7 @@ func TestRegisterTemplateJobReturnsErrorWhenMonitoringEvaluationFails(t *testing
 	apiClientMock.On("LoadRunnerIDs", mock.AnythingOfType("string")).Return([]string{}, nil)
 	apiClientMock.On("DeleteJob", mock.AnythingOfType("string")).Return(nil)
 
-	environment := &NomadEnvironment{"", &nomadApi.Job{}, runner.NewLocalRunnerStorage(), apiClientMock}
+	environment := &NomadEnvironment{apiClientMock, "", &nomadApi.Job{}, runner.NewLocalRunnerStorage()}
 	environment.SetID(tests.DefaultEnvironmentIDAsInteger)
 	err := environment.Register()
 
@@ -172,7 +172,7 @@ func TestTwoSampleAddExactlyTwoRunners(t *testing.T) {
 	apiMock.On("RegisterRunnerJob", mock.AnythingOfType("*api.Job")).Return(nil)
 
 	_, job := helpers.CreateTemplateJob()
-	environment := &NomadEnvironment{templateEnvironmentJobHCL, job, runner.NewLocalRunnerStorage(), apiMock}
+	environment := &NomadEnvironment{apiMock, templateEnvironmentJobHCL, job, runner.NewLocalRunnerStorage()}
 	runner1 := &runner.RunnerMock{}
 	runner1.On("ID").Return(tests.DefaultRunnerID)
 	runner2 := &runner.RunnerMock{}
@@ -205,7 +205,7 @@ func TestSampleDoesNotSetForcePullFlag(t *testing.T) {
 	})
 
 	_, job := helpers.CreateTemplateJob()
-	environment := &NomadEnvironment{templateEnvironmentJobHCL, job, runner.NewLocalRunnerStorage(), apiMock}
+	environment := &NomadEnvironment{apiMock, templateEnvironmentJobHCL, job, runner.NewLocalRunnerStorage()}
 	runner1 := &runner.RunnerMock{}
 	runner1.On("ID").Return(tests.DefaultRunnerID)
 	environment.AddRunner(runner1)

internal/environment/nomad_manager.go

@@ -21,7 +21,6 @@ var log = logging.GetLogger("environment")
 
 type NomadEnvironmentManager struct {
 	*AbstractManager
-	runnerManager          runner.Manager
 	api                    nomad.ExecutorAPI
 	templateEnvironmentHCL string
 }
@@ -35,7 +34,7 @@ func NewNomadEnvironmentManager(
 		return nil, err
 	}
 
-	m := &NomadEnvironmentManager{&AbstractManager{nil}, runnerManager,
+	m := &NomadEnvironmentManager{&AbstractManager{nil, runnerManager},
 		apiClient, templateEnvironmentJobHCL}
 	if err := m.Load(); err != nil {
 		log.WithError(err).Error("Error recovering the execution environments")
@@ -121,19 +120,6 @@ func (m *NomadEnvironmentManager) CreateOrUpdate(id dto.EnvironmentID, request d
 	return !isExistingEnvironment, nil
 }
 
-func (m *NomadEnvironmentManager) Delete(id dto.EnvironmentID) (bool, error) {
-	executionEnvironment, ok := m.runnerManager.GetEnvironment(id)
-	if !ok {
-		return false, nil
-	}
-	m.runnerManager.DeleteEnvironment(id)
-	err := executionEnvironment.Delete()
-	if err != nil {
-		return true, fmt.Errorf("could not delete environment: %w", err)
-	}
-	return true, nil
-}
-
 func (m *NomadEnvironmentManager) Statistics() map[dto.EnvironmentID]*dto.StatisticalExecutionEnvironmentData {
 	return m.runnerManager.EnvironmentStatistics()
 }
@@ -156,10 +142,10 @@ func (m *NomadEnvironmentManager) Load() error {
 			continue
 		}
 		environment := &NomadEnvironment{
+			apiClient:   m.api,
 			jobHCL:      templateEnvironmentJobHCL,
 			job:         job,
 			idleRunners: runner.NewLocalRunnerStorage(),
-			apiClient:   m.api,
 		}
 		m.runnerManager.StoreEnvironment(environment)
 		jobLogger.Info("Successfully recovered environment")
@@ -195,10 +181,10 @@ func fetchEnvironment(id dto.EnvironmentID, apiClient nomad.ExecutorAPI) (runner
 		}
 		if id == environmentID {
 			fetchedEnvironment = &NomadEnvironment{
+				apiClient:   apiClient,
 				jobHCL:      templateEnvironmentJobHCL,
 				job:         job,
 				idleRunners: runner.NewLocalRunnerStorage(),
-				apiClient:   apiClient,
 			}
 		}
 	}

internal/environment/nomad_manager_test.go

@@ -44,7 +44,7 @@ func (s *CreateOrUpdateTestSuite) SetupTest() {
 	}
 
 	s.manager = &NomadEnvironmentManager{
-		runnerManager:          &s.runnerManagerMock,
+		AbstractManager:        &AbstractManager{runnerManager: &s.runnerManagerMock},
 		api:                    &s.apiMock,
 		templateEnvironmentHCL: templateEnvironmentJobHCL,
 	}

internal/runner/aws_manager_test.go

@@ -45,7 +45,7 @@ func TestAWSRunnerManager_Claim(t *testing.T) {
 		assert.NotNil(t, r)
 	})
 
-	t.Run("forwards request for non AWS environments", func(t *testing.T) {
+	t.Run("forwards request for non-AWS environments", func(t *testing.T) {
 		nextHandler := &ManagerMock{}
 		nextHandler.On("Claim", mock.AnythingOfType("dto.EnvironmentID"), mock.AnythingOfType("int")).
 			Return(nil, nil)
@@ -74,7 +74,7 @@ func TestAWSRunnerManager_Return(t *testing.T) {
 		assert.NotContains(t, m.usedRunners.List(), r)
 	})
 
-	t.Run("calls nextHandler for non AWS runner", func(t *testing.T) {
+	t.Run("calls nextHandler for non-AWS runner", func(t *testing.T) {
 		nextHandler := &ManagerMock{}
 		nextHandler.On("Return", mock.AnythingOfType("*runner.NomadJob")).Return(nil)
 		m.SetNextHandler(nextHandler)

internal/runner/aws_runner.go

@@ -13,7 +13,7 @@ import (
 	"io"
 )
 
-var ErrWrongMessageType = errors.New("received message that is not a text messages")
+var ErrWrongMessageType = errors.New("received message that is not a text message")
 
 type awsFunctionRequest struct {
 	Action string                  `json:"action"`
@@ -22,6 +22,9 @@ type awsFunctionRequest struct {
 }
 
 // AWSFunctionWorkload is an abstraction to build a request to an AWS Lambda Function.
+// It is not persisted on a Poseidon restart.
+// The InactivityTimer is used actively. It stops listening to the Lambda function.
+// AWS terminates the Lambda Function after the [Globals.Function.Timeout](deploy/aws/template.yaml).
 type AWSFunctionWorkload struct {
 	InactivityTimer
 	id                string
@@ -88,6 +91,9 @@ func (w *AWSFunctionWorkload) ExecuteInteractively(id string, _ io.ReadWriter, s
 }
 
 // UpdateFileSystem copies Files into the executor.
+// Current limitation: No files can be deleted apart from the previously added files.
+// Future Work: Deduplication of the file systems, as the largest workload is likely to be used by additional
+// CSV files or similar, which are the same for many executions.
 func (w *AWSFunctionWorkload) UpdateFileSystem(request *dto.UpdateFileSystemRequest) error {
 	for _, path := range request.Delete {
 		delete(w.fs, path)
@@ -136,7 +142,9 @@ func (w *AWSFunctionWorkload) executeCommand(ctx context.Context, command []stri
 		return
 	}
 
+	// receiveOutput listens for the execution timeout (or the exit code).
 	exitCode, err := w.receiveOutput(wsConn, stdout, stderr, ctx)
+	// TimeoutPassed checks the runner timeout
 	if w.TimeoutPassed() {
 		err = ErrorRunnerInactivityTimeout
 	}

internal/runner/aws_runner_test.go

@@ -67,7 +67,7 @@ func TestAWSFunctionWorkload_ExecuteInteractively(t *testing.T) {
 	s := httptest.NewServer(http.HandlerFunc(awsMock.handler))
 
 	t.Run("establishes WebSocket connection to AWS endpoint", func(t *testing.T) {
-		// Convert http://127.0.0.1 to ws://127.0.0.
+		// Convert http://127.0.0.1 to ws://127.0.0.1
 		config.Config.AWS.Endpoint = "ws" + strings.TrimPrefix(s.URL, "http")
 		awsMock.ctx, cancel = context.WithCancel(context.Background())
 		cancel()
@@ -107,7 +107,7 @@ func TestAWSFunctionWorkload_UpdateFileSystem(t *testing.T) {
 	awsMock := &awsEndpointMock{}
 	s := httptest.NewServer(http.HandlerFunc(awsMock.handler))
 
-	// Convert http://127.0.0.1 to ws://127.0.0.
+	// Convert http://127.0.0.1 to ws://127.0.0.1
 	config.Config.AWS.Endpoint = "ws" + strings.TrimPrefix(s.URL, "http")
 	awsMock.ctx, cancel = context.WithTimeout(context.Background(), tests.ShortTimeout)
 	defer cancel()

internal/runner/manager.go

@@ -75,7 +75,7 @@ type EnvironmentAccessor interface {
 	EnvironmentStatistics() map[dto.EnvironmentID]*dto.StatisticalExecutionEnvironmentData
 }
 
-// AccessorHandler is one handler in te chain of responsibility of runner accessors.
+// AccessorHandler is one handler in the chain of responsibility of runner accessors.
 // Each runner accessor can handle different requests.
 type AccessorHandler interface {
 	Accessor

internal/runner/nomad_runner.go

@@ -46,6 +46,8 @@ type NomadJob struct {
 }
 
 // NewNomadJob creates a new NomadJob with the provided id.
+// The InactivityTimer is used actively. It executes onDestroy when it has expired.
+// The InactivityTimer is persisted in Nomad by the runner manager's Claim Function.
 func NewNomadJob(id string, portMappings []nomadApi.PortMapping,
 	apiClient nomad.ExecutorAPI, onDestroy DestroyRunnerHandler,
 ) *NomadJob {