Remove the concept of a root dir out of engine

This makes the engine more general purpose so that we can
use it and the job routing functionality for reexec'ing our binary
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)

Conflicts:
	integration/runtime_test.go

docker/docker.go

@@ -7,6 +7,7 @@ import (
 	"io/ioutil"
 	"log"
 	"os"
+	"runtime"
 	"strings"
 
 	"github.com/dotcloud/docker/api"
@@ -121,7 +122,10 @@ func main() {
 			}
 		}
 
-		eng, err := engine.New(realRoot)
+		if err := checkKernelAndArch(); err != nil {
+			log.Fatal(err)
+		}
+		eng, err := engine.New()
 		if err != nil {
 			log.Fatal(err)
 		}
@@ -239,3 +243,27 @@ func main() {
 func showVersion() {
 	fmt.Printf("Docker version %s, build %s\n", dockerversion.VERSION, dockerversion.GITCOMMIT)
 }
+
+func checkKernelAndArch() error {
+	// Check for unsupported architectures
+	if runtime.GOARCH != "amd64" {
+		return fmt.Errorf("The docker runtime currently only supports amd64 (not %s). This will change in the future. Aborting.", runtime.GOARCH)
+	}
+	// Check for unsupported kernel versions
+	// FIXME: it would be cleaner to not test for specific versions, but rather
+	// test for specific functionalities.
+	// Unfortunately we can't test for the feature "does not cause a kernel panic"
+	// without actually causing a kernel panic, so we need this workaround until
+	// the circumstances of pre-3.8 crashes are clearer.
+	// For details see http://github.com/dotcloud/docker/issues/407
+	if k, err := utils.GetKernelVersion(); err != nil {
+		log.Printf("WARNING: %s\n", err)
+	} else {
+		if utils.CompareKernelVersion(k, &utils.KernelVersionInfo{Kernel: 3, Major: 8, Minor: 0}) < 0 {
+			if os.Getenv("DOCKER_NOWARN_KERNEL_VERSION") == "" {
+				log.Printf("WARNING: You are running linux kernel version %s, which might be unstable running docker. Please upgrade your kernel to 3.8.0.", k.String())
+			}
+		}
+	}
+	return nil
+}

engine/engine.go

@@ -5,9 +5,7 @@ import (
 	"fmt"
 	"github.com/dotcloud/docker/utils"
 	"io"
-	"log"
 	"os"
-	"runtime"
 	"sort"
 	"strings"
 )
@@ -37,7 +35,6 @@ func unregister(name string) {
 // It acts as a store for *containers*, and allows manipulation of these
 // containers by executing *jobs*.
 type Engine struct {
-	root     string
 	handlers map[string]Handler
 	hack     Hack // data for temporary hackery (see hack.go)
 	id       string
@@ -47,10 +44,6 @@ type Engine struct {
 	Logging  bool
 }
 
-func (eng *Engine) Root() string {
-	return eng.root
-}
-
 func (eng *Engine) Register(name string, handler Handler) error {
 	_, exists := eng.handlers[name]
 	if exists {
@@ -60,38 +53,9 @@ func (eng *Engine) Register(name string, handler Handler) error {
 	return nil
 }
 
-// New initializes a new engine managing the directory specified at `root`.
+// New initializes a new engine.
-// `root` is used to store containers and any other state private to the engine.
+func New() (*Engine, error) {
-// Changing the contents of the root without executing a job will cause unspecified
-// behavior.
-func New(root string) (*Engine, error) {
-	// Check for unsupported architectures
-	if runtime.GOARCH != "amd64" {
-		return nil, fmt.Errorf("The docker runtime currently only supports amd64 (not %s). This will change in the future. Aborting.", runtime.GOARCH)
-	}
-	// Check for unsupported kernel versions
-	// FIXME: it would be cleaner to not test for specific versions, but rather
-	// test for specific functionalities.
-	// Unfortunately we can't test for the feature "does not cause a kernel panic"
-	// without actually causing a kernel panic, so we need this workaround until
-	// the circumstances of pre-3.8 crashes are clearer.
-	// For details see http://github.com/dotcloud/docker/issues/407
-	if k, err := utils.GetKernelVersion(); err != nil {
-		log.Printf("WARNING: %s\n", err)
-	} else {
-		if utils.CompareKernelVersion(k, &utils.KernelVersionInfo{Kernel: 3, Major: 8, Minor: 0}) < 0 {
-			if os.Getenv("DOCKER_NOWARN_KERNEL_VERSION") == "" {
-				log.Printf("WARNING: You are running linux kernel version %s, which might be unstable running docker. Please upgrade your kernel to 3.8.0.", k.String())
-			}
-		}
-	}
-
-	if err := os.MkdirAll(root, 0700); err != nil && !os.IsExist(err) {
-		return nil, err
-	}
-
 	eng := &Engine{
-		root:     root,
 		handlers: make(map[string]Handler),
 		id:       utils.RandomString(),
 		Stdout:   os.Stdout,
@@ -113,7 +77,7 @@ func New(root string) (*Engine, error) {
 }
 
 func (eng *Engine) String() string {
-	return fmt.Sprintf("%s|%s", eng.Root(), eng.id[:8])
+	return fmt.Sprintf("%s", eng.id[:8])
 }
 
 // Commands returns a list of all currently registered commands,

engine/engine_test.go

@@ -2,10 +2,6 @@ package engine
 
 import (
 	"bytes"
-	"io/ioutil"
-	"os"
-	"path"
-	"path/filepath"
 	"strings"
 	"testing"
 )
@@ -67,7 +63,6 @@ func TestJob(t *testing.T) {
 
 func TestEngineCommands(t *testing.T) {
 	eng := newTestEngine(t)
-	defer os.RemoveAll(eng.Root())
 	handler := func(job *Job) Status { return StatusOK }
 	eng.Register("foo", handler)
 	eng.Register("bar", handler)
@@ -83,44 +78,9 @@ func TestEngineCommands(t *testing.T) {
 	}
 }
 
-func TestEngineRoot(t *testing.T) {
-	tmp, err := ioutil.TempDir("", "docker-test-TestEngineCreateDir")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer os.RemoveAll(tmp)
-	// We expect Root to resolve to an absolute path.
-	// FIXME: this should not be necessary.
-	// Until the above FIXME is implemented, let's check for the
-	// current behavior.
-	tmp, err = filepath.EvalSymlinks(tmp)
-	if err != nil {
-		t.Fatal(err)
-	}
-	tmp, err = filepath.Abs(tmp)
-	if err != nil {
-		t.Fatal(err)
-	}
-	dir := path.Join(tmp, "dir")
-	eng, err := New(dir)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if st, err := os.Stat(dir); err != nil {
-		t.Fatal(err)
-	} else if !st.IsDir() {
-		t.Fatalf("engine.New() created something other than a directory at %s", dir)
-	}
-	if r := eng.Root(); r != dir {
-		t.Fatalf("Expected: %v\nReceived: %v", dir, r)
-	}
-}
-
 func TestEngineString(t *testing.T) {
 	eng1 := newTestEngine(t)
-	defer os.RemoveAll(eng1.Root())
 	eng2 := newTestEngine(t)
-	defer os.RemoveAll(eng2.Root())
 	s1 := eng1.String()
 	s2 := eng2.String()
 	if eng1 == eng2 {
@@ -130,7 +90,6 @@ func TestEngineString(t *testing.T) {
 
 func TestEngineLogf(t *testing.T) {
 	eng := newTestEngine(t)
-	defer os.RemoveAll(eng.Root())
 	input := "Test log line"
 	if n, err := eng.Logf("%s\n", input); err != nil {
 		t.Fatal(err)
@@ -141,7 +100,6 @@ func TestEngineLogf(t *testing.T) {
 
 func TestParseJob(t *testing.T) {
 	eng := newTestEngine(t)
-	defer os.RemoveAll(eng.Root())
 	// Verify that the resulting job calls to the right place
 	var called bool
 	eng.Register("echo", func(job *Job) Status {

engine/helpers_test.go

@@ -1,18 +1,13 @@
 package engine
 
 import (
-	"github.com/dotcloud/docker/utils"
 	"testing"
 )
 
 var globalTestID string
 
 func newTestEngine(t *testing.T) *Engine {
-	tmp, err := utils.TestDirectory("")
+	eng, err := New()
-	if err != nil {
-		t.Fatal(err)
-	}
-	eng, err := New(tmp)
 	if err != nil {
 		t.Fatal(err)
 	}

engine/job_test.go

@@ -1,13 +1,11 @@
 package engine
 
 import (
-	"os"
 	"testing"
 )
 
 func TestJobStatusOK(t *testing.T) {
 	eng := newTestEngine(t)
-	defer os.RemoveAll(eng.Root())
 	eng.Register("return_ok", func(job *Job) Status { return StatusOK })
 	err := eng.Job("return_ok").Run()
 	if err != nil {
@@ -17,7 +15,6 @@ func TestJobStatusOK(t *testing.T) {
 
 func TestJobStatusErr(t *testing.T) {
 	eng := newTestEngine(t)
-	defer os.RemoveAll(eng.Root())
 	eng.Register("return_err", func(job *Job) Status { return StatusErr })
 	err := eng.Job("return_err").Run()
 	if err == nil {
@@ -27,7 +24,6 @@ func TestJobStatusErr(t *testing.T) {
 
 func TestJobStatusNotFound(t *testing.T) {
 	eng := newTestEngine(t)
-	defer os.RemoveAll(eng.Root())
 	eng.Register("return_not_found", func(job *Job) Status { return StatusNotFound })
 	err := eng.Job("return_not_found").Run()
 	if err == nil {
@@ -37,7 +33,6 @@ func TestJobStatusNotFound(t *testing.T) {
 
 func TestJobStdoutString(t *testing.T) {
 	eng := newTestEngine(t)
-	defer os.RemoveAll(eng.Root())
 	// FIXME: test multiple combinations of output and status
 	eng.Register("say_something_in_stdout", func(job *Job) Status {
 		job.Printf("Hello world\n")
@@ -59,7 +54,6 @@ func TestJobStdoutString(t *testing.T) {
 
 func TestJobStderrString(t *testing.T) {
 	eng := newTestEngine(t)
-	defer os.RemoveAll(eng.Root())
 	// FIXME: test multiple combinations of output and status
 	eng.Register("say_something_in_stderr", func(job *Job) Status {
 		job.Errorf("Warning, something might happen\nHere it comes!\nOh no...\nSomething happened\n")

integration/runtime_test.go

@@ -627,10 +627,9 @@ func TestRestore(t *testing.T) {
 
 	// Here are are simulating a docker restart - that is, reloading all containers
 	// from scratch
-	eng = newTestEngine(t, false, eng.Root())
+	eng = newTestEngine(t, false, runtime.Config().Root)
-	daemon2 := mkDaemonFromEngine(eng, t)
+	if len(runtime2.List()) != 2 {
-	if len(daemon2.List()) != 2 {
+		t.Errorf("Expected 2 container, %v found", len(runtime2.List()))
-		t.Errorf("Expected 2 container, %v found", len(daemon2.List()))
 	}
 	runningCount := 0
 	for _, c := range daemon2.List() {

integration/server_test.go

@@ -149,7 +149,7 @@ func TestRestartKillWait(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	eng = newTestEngine(t, false, eng.Root())
+	eng = newTestEngine(t, false, runtime.Config().Root)
 	srv = mkServerFromEngine(eng, t)
 
 	job = srv.Eng.Job("containers")

integration/utils_test.go

@@ -181,7 +181,7 @@ func newTestEngine(t utils.Fataler, autorestart bool, root string) *engine.Engin
 			root = dir
 		}
 	}
-	eng, err := engine.New(root)
+	eng, err := engine.New()
 	if err != nil {
 		t.Fatal(err)
 	}