Introduce ExecutableNotFoundError

In the event that an executable to be run by runc doesn't exist, the
error returned has a concrete type.

[#110522896]

Signed-off-by: Claudia Beresford <[email protected]>
Signed-off-by: Julia Nedialkova <[email protected]>

gqt/run_linux_test.go

@@ -502,6 +502,46 @@ var _ = Describe("Run", func() {
 			Eventually(status).Should(Receive(BeEquivalentTo(42)))
 		})
 	})
+
+	Describe("Errors", func() {
+		Context("when trying to run an executable which does not exist", func() {
+			var (
+				runErr     error
+				binaryPath string
+			)
+
+			JustBeforeEach(func() {
+				client = runner.Start(config)
+
+				container, err := client.Create(garden.ContainerSpec{})
+				Expect(err).NotTo(HaveOccurred())
+
+				_, runErr = container.Run(garden.ProcessSpec{
+					Path: binaryPath,
+				}, garden.ProcessIO{})
+			})
+
+			Context("when the executable is a fully qualified path", func() {
+				BeforeEach(func() {
+					binaryPath = "/bin/fake"
+				})
+
+				It("returns a useful error type", func() {
+					Expect(runErr).To(BeAssignableToTypeOf(garden.ExecutableNotFoundError{}))
+				})
+			})
+
+			Context("when the executable should be somewhere on the $PATH", func() {
+				BeforeEach(func() {
+					binaryPath = "fake-path"
+				})
+
+				It("returns a useful error type", func() {
+					Expect(runErr).To(BeAssignableToTypeOf(garden.ExecutableNotFoundError{}))
+				})
+			})
+		})
+	})
 })
 
 var _ = Describe("Attach", func() {

logging/logconverter.go

@@ -37,13 +37,17 @@ func (e WrappedError) Error() string {
 }
 
 func WrapWithErrorFromLastLogLine(tag string, originalError error, logfileContent []byte) error {
-	msg := lastNonEmptyLine(logfileContent)
+	return WrappedError{Underlying: originalError, tag: tag, lastRuncLogLine: MsgFromLastLogLine(logfileContent)}
+}
+
+func MsgFromLastLogLine(logFileContent []byte) string {
+	msg := lastNonEmptyLine(logFileContent)
 	var line logLine
 	if err := json.Unmarshal(msg, &line); err == nil {
 		msg = []byte(line.Msg)
 	}
 
-	return WrappedError{Underlying: originalError, tag: tag, lastRuncLogLine: string(msg)}
+	return string(msg)
 }
 
 func lastNonEmptyLine(content []byte) []byte {

rundmc/execrunner/dadoo/execrunner.go

@@ -9,6 +9,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"regexp"
 	"strconv"
 	"sync"
 	"syscall"
@@ -136,9 +137,16 @@ func (d *ExecRunner) Run(
 
 	defer func() {
 		lastLogLine := <-doneReadingRuncLogs
-		if theErr != nil {
-			theErr = logging.WrapWithErrorFromLastLogLine("runc exec", theErr, lastLogLine)
+		if theErr == nil {
+			return
 		}
+
+		if isNoSuchExecutable(lastLogLine) {
+			theErr = garden.ExecutableNotFoundError{Message: logging.MsgFromLastLogLine(lastLogLine)}
+			return
+		}
+
+		theErr = logging.WrapWithErrorFromLastLogLine("runc exec", theErr, lastLogLine)
 	}()
 
 	log.Info("read-exit-fd")
@@ -155,6 +163,13 @@ func (d *ExecRunner) Run(
 	return process, nil
 }
 
+func isNoSuchExecutable(logLine []byte) bool {
+	noSuchFile := regexp.MustCompile(`starting container process caused \\"exec: .*: stat .*: no such file or directory`)
+	executableNotFound := regexp.MustCompile(`starting container process caused \\"exec: .*: executable file not found in \$PATH`)
+
+	return noSuchFile.Match(logLine) || executableNotFound.Match(logLine)
+}
+
 func buildDadooCommand(tty bool, dadooPath, dadooRunMode, runcPath, processID, processPath, sandboxHandle string, extraFiles []*os.File, stdin io.Reader) *exec.Cmd {
 	dadooArgs := []string{}
 	if tty {

rundmc/execrunner/dadoo/execrunner_linux_test.go

@@ -391,6 +391,38 @@ var _ = Describe("Dadoo ExecRunner", func() {
 					close(done)
 				}, 10.0)
 			})
+
+			Context("when runc tries to exec a non-existent binary", func() {
+				Context("when the binary is not on the $PATH", func() {
+					BeforeEach(func() {
+						dadooWritesLogs = `{"time":"2016-03-02T13:56:38Z", "level":"fatal", "msg":"starting container process caused \"exec: \\\"potato\\\": executable file not found in $PATH\""}`
+					})
+
+					It("Returns a garden.RequestedBinaryNotFoundError error", func() {
+						_, err := runner.Run(log, processID, processPath, "some-handle", bundlePath, 123, 456, defaultProcessIO(), false, nil, nil)
+
+						message := `starting container process caused "exec: \"potato\": executable file not found in $PATH"`
+						expectedErr := garden.ExecutableNotFoundError{Message: message}
+
+						Expect(err).To(MatchError(expectedErr))
+					})
+				})
+
+				Context("when a fully qualified binary does not exist", func() {
+					BeforeEach(func() {
+						dadooWritesLogs = `{"time":"2016-03-02T13:56:38Z", "level":"fatal", "msg":"starting container process caused \"exec: \\\"/bin/potato\\\": stat /bin/potato: no such file or directory\""}`
+					})
+
+					It("Returns a garden.RequestedBinaryNotFoundError error", func() {
+						_, err := runner.Run(log, processID, processPath, "some-handle", bundlePath, 123, 456, defaultProcessIO(), false, nil, nil)
+
+						message := `starting container process caused "exec: \"/bin/potato\": stat /bin/potato: no such file or directory"`
+						expectedErr := garden.ExecutableNotFoundError{Message: message}
+
+						Expect(err).To(MatchError(expectedErr))
+					})
+				})
+			})
 		})
 
 		Context("when dadoo panics before reporting runc's exit code", func() {