Don't embed the execution.Storer interface into a runner

Previously, the execution.Storer interface was embedded in the Runner interface.
However, this resulted in calls like runner.Add(...) to add an execution to the
store which is kind of ugly. Thus, we decided to add only the required functions to
the runner interface and make the execution.Storer a field of the implementation.

internal/api/runners.go

@@ -8,7 +8,6 @@ import (
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/internal/config"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/internal/runner"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/pkg/dto"
-	"gitlab.hpi.de/codeocean/codemoon/poseidon/pkg/execution"
 	"net/http"
 	"net/url"
 )
@@ -113,8 +112,8 @@ func (r *RunnerController) execute(writer http.ResponseWriter, request *http.Req
 		writeInternalServerError(writer, err, dto.ErrorUnknown)
 		return
 	}
-	id := execution.ID(newUUID.String())
+	id := newUUID.String()
-	targetRunner.Add(id, executionRequest)
+	targetRunner.StoreExecution(id, executionRequest)
 	webSocketURL := url.URL{
 		Scheme:   scheme,
 		Host:     request.Host,

internal/api/runners_test.go

@@ -9,7 +9,6 @@ import (
 	"github.com/stretchr/testify/suite"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/internal/runner"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/pkg/dto"
-	"gitlab.hpi.de/codeocean/codemoon/poseidon/pkg/execution"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/tests"
 	"net/http"
 	"net/http/httptest"
@@ -86,15 +85,15 @@ type RunnerRouteTestSuite struct {
 	runnerManager *runner.ManagerMock
 	router        *mux.Router
 	runner        runner.Runner
-	executionID   execution.ID
+	executionID   string
 }
 
 func (s *RunnerRouteTestSuite) SetupTest() {
 	s.runnerManager = &runner.ManagerMock{}
 	s.router = NewRouter(s.runnerManager, nil)
 	s.runner = runner.NewNomadJob("some-id", nil, nil, nil)
-	s.executionID = "execution-id"
+	s.executionID = "execution"
-	s.runner.Add(s.executionID, &dto.ExecutionRequest{})
+	s.runner.StoreExecution(s.executionID, &dto.ExecutionRequest{})
 	s.runnerManager.On("Get", s.runner.ID()).Return(s.runner, nil)
 }
 
@@ -201,10 +200,9 @@ func (s *RunnerRouteTestSuite) TestExecuteRoute() {
 			webSocketURL, err := url.Parse(webSocketResponse.WebSocketURL)
 			s.Require().NoError(err)
 			executionID := webSocketURL.Query().Get(ExecutionIDKey)
-			storedExecutionRequest, ok := s.runner.Pop(execution.ID(executionID))
+			ok := s.runner.ExecutionExists(executionID)
 
 			s.True(ok, "No execution request with this id: ", executionID)
-			s.Equal(&executionRequest, storedExecutionRequest)
 		})
 	})
 

internal/api/websocket.go

@@ -8,7 +8,6 @@ import (
 	"github.com/gorilla/websocket"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/internal/runner"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/pkg/dto"
-	"gitlab.hpi.de/codeocean/codemoon/poseidon/pkg/execution"
 	"io"
 	"net/http"
 	"sync"
@@ -299,9 +298,8 @@ func (wp *webSocketProxy) writeMessage(messageType int, data []byte) error {
 // connectToRunner is the endpoint for websocket connections.
 func (r *RunnerController) connectToRunner(writer http.ResponseWriter, request *http.Request) {
 	targetRunner, _ := runner.FromContext(request.Context())
-	executionID := execution.ID(request.URL.Query().Get(ExecutionIDKey))
+	executionID := request.URL.Query().Get(ExecutionIDKey)
-	executionRequest, ok := targetRunner.Pop(executionID)
+	if !targetRunner.ExecutionExists(executionID) {
-	if !ok {
 		writeNotFound(writer, ErrUnknownExecutionID)
 		return
 	}
@@ -317,7 +315,11 @@ func (r *RunnerController) connectToRunner(writer http.ResponseWriter, request *
 	}
 
 	log.WithField("runnerId", targetRunner.ID()).WithField("executionID", executionID).Info("Running execution")
-	exit, cancel := targetRunner.ExecuteInteractively(executionRequest, proxy.Stdin, proxy.Stdout, proxy.Stderr)
+	exit, cancel, err := targetRunner.ExecuteInteractively(executionID, proxy.Stdin, proxy.Stdout, proxy.Stderr)
+	if err != nil {
+		proxy.closeWithError(fmt.Sprintf("execution failed with: %v", err))
+		return
+	}
 
 	proxy.waitForExit(exit, cancel)
 }

internal/api/websocket_test.go

@@ -15,7 +15,6 @@ import (
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/internal/nomad"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/internal/runner"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/pkg/dto"
-	"gitlab.hpi.de/codeocean/codemoon/poseidon/pkg/execution"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/tests"
 	"gitlab.hpi.de/codeocean/codemoon/poseidon/tests/helpers"
 	"io"
@@ -34,7 +33,7 @@ func TestWebSocketTestSuite(t *testing.T) {
 type WebSocketTestSuite struct {
 	suite.Suite
 	router      *mux.Router
-	executionID execution.ID
+	executionID string
 	runner      runner.Runner
 	apiMock     *nomad.ExecutorAPIMock
 	server      *httptest.Server
@@ -46,7 +45,7 @@ func (s *WebSocketTestSuite) SetupTest() {
 
 	// default execution
 	s.executionID = "execution-id"
-	s.runner.Add(s.executionID, &executionRequestHead)
+	s.runner.StoreExecution(s.executionID, &executionRequestHead)
 	mockAPIExecuteHead(s.apiMock)
 
 	runnerManager := &runner.ManagerMock{}
@@ -125,8 +124,8 @@ func (s *WebSocketTestSuite) TestWebsocketConnection() {
 }
 
 func (s *WebSocketTestSuite) TestCancelWebSocketConnection() {
-	executionID := execution.ID("sleeping-execution")
+	executionID := "sleeping-execution"
-	s.runner.Add(executionID, &executionRequestSleep)
+	s.runner.StoreExecution(executionID, &executionRequestSleep)
 	canceled := mockAPIExecuteSleep(s.apiMock)
 
 	wsURL, err := webSocketURL("ws", s.server, s.router, s.runner.ID(), executionID)
@@ -156,10 +155,10 @@ func (s *WebSocketTestSuite) TestCancelWebSocketConnection() {
 }
 
 func (s *WebSocketTestSuite) TestWebSocketConnectionTimeout() {
-	executionID := execution.ID("time-out-execution")
+	executionID := "time-out-execution"
 	limitExecution := executionRequestSleep
 	limitExecution.TimeLimit = 2
-	s.runner.Add(executionID, &limitExecution)
+	s.runner.StoreExecution(executionID, &limitExecution)
 	canceled := mockAPIExecuteSleep(s.apiMock)
 
 	wsURL, err := webSocketURL("ws", s.server, s.router, s.runner.ID(), executionID)
@@ -190,8 +189,8 @@ func (s *WebSocketTestSuite) TestWebSocketConnectionTimeout() {
 }
 
 func (s *WebSocketTestSuite) TestWebsocketStdoutAndStderr() {
-	executionID := execution.ID("ls-execution")
+	executionID := "ls-execution"
-	s.runner.Add(executionID, &executionRequestLs)
+	s.runner.StoreExecution(executionID, &executionRequestLs)
 	mockAPIExecuteLs(s.apiMock)
 
 	wsURL, err := webSocketURL("ws", s.server, s.router, s.runner.ID(), executionID)
@@ -210,8 +209,8 @@ func (s *WebSocketTestSuite) TestWebsocketStdoutAndStderr() {
 }
 
 func (s *WebSocketTestSuite) TestWebsocketError() {
-	executionID := execution.ID("error-execution")
+	executionID := "error-execution"
-	s.runner.Add(executionID, &executionRequestError)
+	s.runner.StoreExecution(executionID, &executionRequestError)
 	mockAPIExecuteError(s.apiMock)
 
 	wsURL, err := webSocketURL("ws", s.server, s.router, s.runner.ID(), executionID)
@@ -229,8 +228,8 @@ func (s *WebSocketTestSuite) TestWebsocketError() {
 }
 
 func (s *WebSocketTestSuite) TestWebsocketNonZeroExit() {
-	executionID := execution.ID("exit-execution")
+	executionID := "exit-execution"
-	s.runner.Add(executionID, &executionRequestExitNonZero)
+	s.runner.StoreExecution(executionID, &executionRequestExitNonZero)
 	mockAPIExecuteExitNonZero(s.apiMock)
 
 	wsURL, err := webSocketURL("ws", s.server, s.router, s.runner.ID(), executionID)
@@ -251,8 +250,8 @@ func TestWebsocketTLS(t *testing.T) {
 	runnerID := "runner-id"
 	r, apiMock := newNomadAllocationWithMockedAPIClient(runnerID)
 
-	executionID := execution.ID("execution-id")
+	executionID := "execution-id"
-	r.Add(executionID, &executionRequestLs)
+	r.StoreExecution(executionID, &executionRequestLs)
 	mockAPIExecuteLs(apiMock)
 
 	runnerManager := &runner.ManagerMock{}
@@ -380,7 +379,7 @@ func newNomadAllocationWithMockedAPIClient(runnerID string) (runner.Runner, *nom
 }
 
 func webSocketURL(scheme string, server *httptest.Server, router *mux.Router,
-	runnerID string, executionID execution.ID,
+	runnerID string, executionID string,
 ) (*url.URL, error) {
 	websocketURL, err := url.Parse(server.URL)
 	if err != nil {
@@ -396,7 +395,7 @@ func webSocketURL(scheme string, server *httptest.Server, router *mux.Router,
 	return websocketURL, nil
 }
 
-func (s *WebSocketTestSuite) webSocketURL(scheme, runnerID string, executionID execution.ID) (*url.URL, error) {
+func (s *WebSocketTestSuite) webSocketURL(scheme, runnerID, executionID string) (*url.URL, error) {
 	return webSocketURL(scheme, s.server, s.router, runnerID, executionID)
 }
 

internal/runner/runner.go

@@ -29,26 +29,40 @@ const (
 	executionTimeoutGracePeriod = 3 * time.Second
 )
 
-var ErrorFileCopyFailed = errors.New("file copy failed")
+var (
+	ErrorUnknownExecution = errors.New("unknown execution")
+	ErrorFileCopyFailed   = errors.New("file copy failed")
+)
+
+type ExitInfo struct {
+	Code uint8
+	Err  error
+}
 
 type Runner interface {
+	InactivityTimer
+
 	// ID returns the id of the runner.
 	ID() string
+
 	// MappedPorts returns the mapped ports of the runner.
 	MappedPorts() []*dto.MappedPort
 
-	execution.Storer
+	// StoreExecution adds a new execution to the runner that can then be executed using ExecuteInteractively.
-	InactivityTimer
+	StoreExecution(id string, executionRequest *dto.ExecutionRequest)
+
+	// ExecutionExists returns whether the execution with the given id is already stored.
+	ExecutionExists(id string) bool
 
 	// ExecuteInteractively runs the given execution request and forwards from and to the given reader and writers.
 	// An ExitInfo is sent to the exit channel on command completion.
 	// Output from the runner is forwarded immediately.
 	ExecuteInteractively(
-		request *dto.ExecutionRequest,
+		id string,
 		stdin io.ReadWriter,
 		stdout,
 		stderr io.Writer,
-	) (exit <-chan ExitInfo, cancel context.CancelFunc)
+	) (exit <-chan ExitInfo, cancel context.CancelFunc, err error)
 
 	// UpdateFileSystem processes a dto.UpdateFileSystemRequest by first deleting each given dto.FilePath recursively
 	// and then copying each given dto.File to the runner.
@@ -60,8 +74,8 @@ type Runner interface {
 
 // NomadJob is an abstraction to communicate with Nomad environments.
 type NomadJob struct {
-	execution.Storer
 	InactivityTimer
+	executions   execution.Storer
 	id           string
 	portMappings []nomadApi.PortMapping
 	api          nomad.ExecutorAPI
@@ -76,7 +90,7 @@ func NewNomadJob(id string, portMappings []nomadApi.PortMapping,
 		id:           id,
 		portMappings: portMappings,
 		api:          apiClient,
-		Storer:       execution.NewLocalStorage(),
+		executions:   execution.NewLocalStorage(),
 		manager:      manager,
 	}
 	job.InactivityTimer = NewInactivityTimer(job, manager)
@@ -98,9 +112,74 @@ func (r *NomadJob) MappedPorts() []*dto.MappedPort {
 	return ports
 }
 
-type ExitInfo struct {
+func (r *NomadJob) StoreExecution(id string, request *dto.ExecutionRequest) {
-	Code uint8
+	r.executions.Add(execution.ID(id), request)
-	Err  error
+}
+
+func (r *NomadJob) ExecutionExists(id string) bool {
+	return r.executions.Exists(execution.ID(id))
+}
+
+func (r *NomadJob) ExecuteInteractively(
+	id string,
+	stdin io.ReadWriter,
+	stdout, stderr io.Writer,
+) (<-chan ExitInfo, context.CancelFunc, error) {
+	request, ok := r.executions.Pop(execution.ID(id))
+	if !ok {
+		return nil, nil, ErrorUnknownExecution
+	}
+
+	r.ResetTimeout()
+
+	command, ctx, cancel := prepareExecution(request)
+	exitInternal := make(chan ExitInfo)
+	exit := make(chan ExitInfo, 1)
+	ctxExecute, cancelExecute := context.WithCancel(context.Background())
+
+	go r.executeCommand(ctxExecute, command, stdin, stdout, stderr, exitInternal)
+	go r.handleExitOrContextDone(ctx, cancelExecute, exitInternal, exit, stdin)
+
+	return exit, cancel, nil
+}
+
+func (r *NomadJob) UpdateFileSystem(copyRequest *dto.UpdateFileSystemRequest) error {
+	r.ResetTimeout()
+
+	var tarBuffer bytes.Buffer
+	if err := createTarArchiveForFiles(copyRequest.Copy, &tarBuffer); err != nil {
+		return err
+	}
+
+	fileDeletionCommand := fileDeletionCommand(copyRequest.Delete)
+	copyCommand := "tar --extract --absolute-names --verbose --file=/dev/stdin;"
+	updateFileCommand := (&dto.ExecutionRequest{Command: fileDeletionCommand + copyCommand}).FullCommand()
+	stdOut := bytes.Buffer{}
+	stdErr := bytes.Buffer{}
+	exitCode, err := r.api.ExecuteCommand(r.id, context.Background(), updateFileCommand, false,
+		&tarBuffer, &stdOut, &stdErr)
+
+	if err != nil {
+		return fmt.Errorf(
+			"%w: nomad error during file copy: %v",
+			nomad.ErrorExecutorCommunicationFailed,
+			err)
+	}
+	if exitCode != 0 {
+		return fmt.Errorf(
+			"%w: stderr output '%s' and stdout output '%s'",
+			ErrorFileCopyFailed,
+			stdErr.String(),
+			stdOut.String())
+	}
+	return nil
+}
+
+func (r *NomadJob) Destroy() error {
+	if err := r.manager.Return(r); err != nil {
+		return fmt.Errorf("error while destroying runner: %w", err)
+	}
+	return nil
 }
 
 func prepareExecution(request *dto.ExecutionRequest) (
@@ -164,61 +243,6 @@ func (r *NomadJob) handleExitOrContextDone(ctx context.Context, cancelExecute co
 	}
 }
 
-func (r *NomadJob) ExecuteInteractively(
-	request *dto.ExecutionRequest,
-	stdin io.ReadWriter,
-	stdout, stderr io.Writer,
-) (<-chan ExitInfo, context.CancelFunc) {
-	r.ResetTimeout()
-
-	command, ctx, cancel := prepareExecution(request)
-	exitInternal := make(chan ExitInfo)
-	exit := make(chan ExitInfo, 1)
-	ctxExecute, cancelExecute := context.WithCancel(context.Background())
-	go r.executeCommand(ctxExecute, command, stdin, stdout, stderr, exitInternal)
-	go r.handleExitOrContextDone(ctx, cancelExecute, exitInternal, exit, stdin)
-	return exit, cancel
-}
-
-func (r *NomadJob) UpdateFileSystem(copyRequest *dto.UpdateFileSystemRequest) error {
-	r.ResetTimeout()
-
-	var tarBuffer bytes.Buffer
-	if err := createTarArchiveForFiles(copyRequest.Copy, &tarBuffer); err != nil {
-		return err
-	}
-
-	fileDeletionCommand := fileDeletionCommand(copyRequest.Delete)
-	copyCommand := "tar --extract --absolute-names --verbose --file=/dev/stdin;"
-	updateFileCommand := (&dto.ExecutionRequest{Command: fileDeletionCommand + copyCommand}).FullCommand()
-	stdOut := bytes.Buffer{}
-	stdErr := bytes.Buffer{}
-	exitCode, err := r.api.ExecuteCommand(r.id, context.Background(), updateFileCommand, false,
-		&tarBuffer, &stdOut, &stdErr)
-
-	if err != nil {
-		return fmt.Errorf(
-			"%w: nomad error during file copy: %v",
-			nomad.ErrorExecutorCommunicationFailed,
-			err)
-	}
-	if exitCode != 0 {
-		return fmt.Errorf(
-			"%w: stderr output '%s' and stdout output '%s'",
-			ErrorFileCopyFailed,
-			stdErr.String(),
-			stdOut.String())
-	}
-	return nil
-}
-
-func (r *NomadJob) Destroy() error {
-	if err := r.manager.Return(r); err != nil {
-		return fmt.Errorf("error while destroying runner: %w", err)
-	}
-	return nil
-}
-
 func createTarArchiveForFiles(filesToCopy []dto.File, w io.Writer) error {
 	tarWriter := tar.NewWriter(w)
 	for _, file := range filesToCopy {

internal/runner/runner_mock.go

@@ -4,7 +4,6 @@ package runner
 
 import (
 	context "context"
-	"gitlab.hpi.de/codeocean/codemoon/poseidon/pkg/execution"
 	io "io"
 
 	dto "gitlab.hpi.de/codeocean/codemoon/poseidon/pkg/dto"
@@ -19,11 +18,6 @@ type RunnerMock struct {
 	mock.Mock
 }
 
-// Add provides a mock function with given fields: id, executionRequest
-func (_m *RunnerMock) Add(id execution.ID, executionRequest *dto.ExecutionRequest) {
-	_m.Called(id, executionRequest)
-}
-
 // Destroy provides a mock function with given fields:
 func (_m *RunnerMock) Destroy() error {
 	ret := _m.Called()
@@ -38,13 +32,13 @@ func (_m *RunnerMock) Destroy() error {
 	return r0
 }
 
-// ExecuteInteractively provides a mock function with given fields: request, stdin, stdout, stderr
+// ExecuteInteractively provides a mock function with given fields: id, stdin, stdout, stderr
-func (_m *RunnerMock) ExecuteInteractively(request *dto.ExecutionRequest, stdin io.ReadWriter, stdout io.Writer, stderr io.Writer) (<-chan ExitInfo, context.CancelFunc) {
+func (_m *RunnerMock) ExecuteInteractively(id string, stdin io.ReadWriter, stdout io.Writer, stderr io.Writer) (<-chan ExitInfo, context.CancelFunc, error) {
-	ret := _m.Called(request, stdin, stdout, stderr)
+	ret := _m.Called(id, stdin, stdout, stderr)
 
 	var r0 <-chan ExitInfo
-	if rf, ok := ret.Get(0).(func(*dto.ExecutionRequest, io.ReadWriter, io.Writer, io.Writer) <-chan ExitInfo); ok {
+	if rf, ok := ret.Get(0).(func(string, io.ReadWriter, io.Writer, io.Writer) <-chan ExitInfo); ok {
-		r0 = rf(request, stdin, stdout, stderr)
+		r0 = rf(id, stdin, stdout, stderr)
 	} else {
 		if ret.Get(0) != nil {
 			r0 = ret.Get(0).(<-chan ExitInfo)
@@ -52,15 +46,36 @@ func (_m *RunnerMock) ExecuteInteractively(request *dto.ExecutionRequest, stdin
 	}
 
 	var r1 context.CancelFunc
-	if rf, ok := ret.Get(1).(func(*dto.ExecutionRequest, io.ReadWriter, io.Writer, io.Writer) context.CancelFunc); ok {
+	if rf, ok := ret.Get(1).(func(string, io.ReadWriter, io.Writer, io.Writer) context.CancelFunc); ok {
-		r1 = rf(request, stdin, stdout, stderr)
+		r1 = rf(id, stdin, stdout, stderr)
 	} else {
 		if ret.Get(1) != nil {
 			r1 = ret.Get(1).(context.CancelFunc)
 		}
 	}
 
-	return r0, r1
+	var r2 error
+	if rf, ok := ret.Get(2).(func(string, io.ReadWriter, io.Writer, io.Writer) error); ok {
+		r2 = rf(id, stdin, stdout, stderr)
+	} else {
+		r2 = ret.Error(2)
+	}
+
+	return r0, r1, r2
+}
+
+// ExecutionExists provides a mock function with given fields: id
+func (_m *RunnerMock) ExecutionExists(id string) bool {
+	ret := _m.Called(id)
+
+	var r0 bool
+	if rf, ok := ret.Get(0).(func(string) bool); ok {
+		r0 = rf(id)
+	} else {
+		r0 = ret.Get(0).(bool)
+	}
+
+	return r0
 }
 
 // ID provides a mock function with given fields:
@@ -93,29 +108,6 @@ func (_m *RunnerMock) MappedPorts() []*dto.MappedPort {
 	return r0
 }
 
-// Pop provides a mock function with given fields: id
-func (_m *RunnerMock) Pop(id execution.ID) (*dto.ExecutionRequest, bool) {
-	ret := _m.Called(id)
-
-	var r0 *dto.ExecutionRequest
-	if rf, ok := ret.Get(0).(func(execution.ID) *dto.ExecutionRequest); ok {
-		r0 = rf(id)
-	} else {
-		if ret.Get(0) != nil {
-			r0 = ret.Get(0).(*dto.ExecutionRequest)
-		}
-	}
-
-	var r1 bool
-	if rf, ok := ret.Get(1).(func(execution.ID) bool); ok {
-		r1 = rf(id)
-	} else {
-		r1 = ret.Get(1).(bool)
-	}
-
-	return r0, r1
-}
-
 // ResetTimeout provides a mock function with given fields:
 func (_m *RunnerMock) ResetTimeout() {
 	_m.Called()
@@ -131,6 +123,11 @@ func (_m *RunnerMock) StopTimeout() {
 	_m.Called()
 }
 
+// StoreExecution provides a mock function with given fields: id, executionRequest
+func (_m *RunnerMock) StoreExecution(id string, executionRequest *dto.ExecutionRequest) {
+	_m.Called(id, executionRequest)
+}
+
 // TimeoutPassed provides a mock function with given fields:
 func (_m *RunnerMock) TimeoutPassed() bool {
 	ret := _m.Called()

internal/runner/runner_test.go

@@ -22,6 +22,8 @@ import (
 	"time"
 )
 
+const defaultExecutionID = "execution-id"
+
 func TestIdIsStored(t *testing.T) {
 	runner := NewNomadJob(tests.DefaultJobID, nil, nil, nil)
 	assert.Equal(t, tests.DefaultJobID, runner.ID())
@@ -49,9 +51,9 @@ func TestExecutionRequestIsStored(t *testing.T) {
 		TimeLimit:   10,
 		Environment: nil,
 	}
-	id := execution.ID("test-execution")
+	id := "test-execution"
-	runner.Add(id, executionRequest)
+	runner.StoreExecution(id, executionRequest)
-	storedExecutionRunner, ok := runner.Pop(id)
+	storedExecutionRunner, ok := runner.executions.Pop(execution.ID(id))
 
 	assert.True(t, ok, "Getting an execution should not return ok false")
 	assert.Equal(t, executionRequest, storedExecutionRunner)
@@ -119,7 +121,7 @@ func (s *ExecuteInteractivelyTestSuite) SetupTest() {
 	s.manager.On("Return", mock.Anything).Return(nil)
 
 	s.runner = &NomadJob{
-		Storer:          execution.NewLocalStorage(),
+		executions:      execution.NewLocalStorage(),
 		InactivityTimer: s.timer,
 		id:              tests.DefaultRunnerID,
 		api:             s.apiMock,
@@ -127,9 +129,16 @@ func (s *ExecuteInteractivelyTestSuite) SetupTest() {
 	}
 }
 
+func (s *ExecuteInteractivelyTestSuite) TestReturnsErrorWhenExecutionDoesNotExist() {
+	_, _, err := s.runner.ExecuteInteractively("non-existent-id", nil, nil, nil)
+	s.ErrorIs(err, ErrorUnknownExecution)
+}
+
 func (s *ExecuteInteractivelyTestSuite) TestCallsApi() {
 	request := &dto.ExecutionRequest{Command: "echo 'Hello World!'"}
-	s.runner.ExecuteInteractively(request, nil, nil, nil)
+	s.runner.StoreExecution(defaultExecutionID, request)
+	_, _, err := s.runner.ExecuteInteractively(defaultExecutionID, nil, nil, nil)
+	s.Require().NoError(err)
 
 	time.Sleep(tests.ShortTimeout)
 	s.apiMock.AssertCalled(s.T(), "ExecuteCommand", tests.DefaultRunnerID, mock.Anything, request.FullCommand(),
@@ -143,7 +152,9 @@ func (s *ExecuteInteractivelyTestSuite) TestReturnsAfterTimeout() {
 
 	timeLimit := 1
 	executionRequest := &dto.ExecutionRequest{TimeLimit: timeLimit}
-	exit, _ := s.runner.ExecuteInteractively(executionRequest, &nullio.ReadWriter{}, nil, nil)
+	s.runner.StoreExecution(defaultExecutionID, executionRequest)
+	exit, _, err := s.runner.ExecuteInteractively(defaultExecutionID, &nullio.ReadWriter{}, nil, nil)
+	s.Require().NoError(err)
 
 	select {
 	case <-exit:
@@ -172,7 +183,9 @@ func (s *ExecuteInteractivelyTestSuite) TestSendsSignalAfterTimeout() {
 	}).Return(0, nil)
 	timeLimit := 1
 	executionRequest := &dto.ExecutionRequest{TimeLimit: timeLimit}
-	_, _ = s.runner.ExecuteInteractively(executionRequest, bytes.NewBuffer(make([]byte, 1)), nil, nil)
+	s.runner.StoreExecution(defaultExecutionID, executionRequest)
+	_, _, err := s.runner.ExecuteInteractively(defaultExecutionID, bytes.NewBuffer(make([]byte, 1)), nil, nil)
+	s.Require().NoError(err)
 	select {
 	case <-time.After(2 * (time.Duration(timeLimit) * time.Second)):
 		s.FailNow("The execution should receive a SIGQUIT after the timeout")
@@ -186,21 +199,27 @@ func (s *ExecuteInteractivelyTestSuite) TestDestroysRunnerAfterTimeoutAndSignal(
 	})
 	timeLimit := 1
 	executionRequest := &dto.ExecutionRequest{TimeLimit: timeLimit}
-	_, _ = s.runner.ExecuteInteractively(executionRequest, bytes.NewBuffer(make([]byte, 1)), nil, nil)
+	s.runner.StoreExecution(defaultExecutionID, executionRequest)
+	_, _, err := s.runner.ExecuteInteractively(defaultExecutionID, bytes.NewBuffer(make([]byte, 1)), nil, nil)
+	s.Require().NoError(err)
 	<-time.After(executionTimeoutGracePeriod + time.Duration(timeLimit)*time.Second + tests.ShortTimeout)
 	s.manager.AssertCalled(s.T(), "Return", s.runner)
 }
 
 func (s *ExecuteInteractivelyTestSuite) TestResetTimerGetsCalled() {
 	executionRequest := &dto.ExecutionRequest{}
-	s.runner.ExecuteInteractively(executionRequest, nil, nil, nil)
+	s.runner.StoreExecution(defaultExecutionID, executionRequest)
+	_, _, err := s.runner.ExecuteInteractively(defaultExecutionID, nil, nil, nil)
+	s.Require().NoError(err)
 	s.timer.AssertCalled(s.T(), "ResetTimeout")
 }
 
 func (s *ExecuteInteractivelyTestSuite) TestExitHasTimeoutErrorIfRunnerTimesOut() {
 	s.mockedTimeoutPassedCall.Return(true)
 	executionRequest := &dto.ExecutionRequest{}
-	exitChannel, _ := s.runner.ExecuteInteractively(executionRequest, &nullio.ReadWriter{}, nil, nil)
+	s.runner.StoreExecution(defaultExecutionID, executionRequest)
+	exitChannel, _, err := s.runner.ExecuteInteractively(defaultExecutionID, &nullio.ReadWriter{}, nil, nil)
+	s.Require().NoError(err)
 	exit := <-exitChannel
 	s.Equal(ErrorRunnerInactivityTimeout, exit.Err)
 }
@@ -225,7 +244,7 @@ func (s *UpdateFileSystemTestSuite) SetupTest() {
 	s.timer.On("ResetTimeout").Return()
 	s.timer.On("TimeoutPassed").Return(false)
 	s.runner = &NomadJob{
-		Storer:          execution.NewLocalStorage(),
+		executions:      execution.NewLocalStorage(),
 		InactivityTimer: s.timer,
 		id:              tests.DefaultRunnerID,
 		api:             s.apiMock,

internal/runner/storage_test.go

@@ -20,7 +20,7 @@ type RunnerPoolTestSuite struct {
 func (s *RunnerPoolTestSuite) SetupTest() {
 	s.runnerStorage = NewLocalRunnerStorage()
 	s.runner = NewRunner(tests.DefaultRunnerID, nil)
-	s.runner.Add(tests.DefaultExecutionID, &dto.ExecutionRequest{Command: "true"})
+	s.runner.StoreExecution(tests.DefaultExecutionID, &dto.ExecutionRequest{Command: "true"})
 }
 
 func (s *RunnerPoolTestSuite) TestAddedRunnerCanBeRetrieved() {

pkg/execution/execution.go

@@ -13,6 +13,9 @@ type Storer interface {
 	// It overwrites the existing execution if an execution with the same id already exists.
 	Add(id ID, executionRequest *dto.ExecutionRequest)
 
+	// Exists returns whether the execution with the given id exists in the store.
+	Exists(id ID) bool
+
 	// Pop deletes the execution with the given id from the storage and returns it.
 	// If no such execution exists, ok is false and true otherwise.
 	Pop(id ID) (request *dto.ExecutionRequest, ok bool)

pkg/execution/local_storage.go

@@ -26,6 +26,13 @@ func (s *localStorage) Add(id ID, executionRequest *dto.ExecutionRequest) {
 	s.executions[id] = executionRequest
 }
 
+func (s *localStorage) Exists(id ID) bool {
+	s.Lock()
+	defer s.Unlock()
+	_, ok := s.executions[id]
+	return ok
+}
+
 func (s *localStorage) Pop(id ID) (*dto.ExecutionRequest, bool) {
 	s.Lock()
 	defer s.Unlock()