@@ -5,6 +5,7 @@ import (

 	"strings"

 	"github.com/docker/docker/pkg/term"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 )

@@ -51,7 +52,7 @@ var helpCommand = &cobra.Command{

 	RunE: func(c *cobra.Command, args []string) error {

 		cmd, args, e := c.Root().Find(args)

 		if cmd == nil || e != nil || len(args) > 0 {

-			return fmt.Errorf("unknown help topic: %v", strings.Join(args, " "))

+			return errors.Errorf("unknown help topic: %v", strings.Join(args, " "))

 		}

 		helpFunc := cmd.HelpFunc()

@@ -2,8 +2,9 @@ package bundlefile

 import (

 	"encoding/json"

-	"fmt"

 	"io"

+

+	"github.com/pkg/errors"

 )

 // Bundlefile stores the contents of a bundlefile

@@ -39,12 +40,12 @@ func LoadFile(reader io.Reader) (*Bundlefile, error) {

 	if err := decoder.Decode(bundlefile); err != nil {

 		switch jsonErr := err.(type) {

 		case *json.SyntaxError:

-			return nil, fmt.Errorf(

+			return nil, errors.Errorf(

 				"JSON syntax error at byte %v: %s",

 				jsonErr.Offset,

 				jsonErr.Error())

 		case *json.UnmarshalTypeError:

-			return nil, fmt.Errorf(

+			return nil, errors.Errorf(

 				"Unexpected type at byte %v. Expected %s but received %s.",

 				jsonErr.Offset,

 				jsonErr.Type,

@@ -1,7 +1,6 @@

 package command

 import (

-	"errors"

 	"fmt"

 	"io"

 	"net/http"

@@ -21,6 +20,7 @@ import (

 	dopts "github.com/docker/docker/opts"

 	"github.com/docker/go-connections/sockets"

 	"github.com/docker/go-connections/tlsconfig"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -1,7 +1,6 @@

 package container

 import (

-	"errors"

 	"io"

 	"net/http/httputil"

@@ -10,6 +9,7 @@ import (

 	"github.com/docker/docker/cli"

 	"github.com/docker/docker/cli/command"

 	"github.com/docker/docker/pkg/signal"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -1,8 +1,6 @@

 package container

 import (

-	"errors"

-	"fmt"

 	"io"

 	"os"

 	"path/filepath"

@@ -13,6 +11,7 @@ import (

 	"github.com/docker/docker/cli/command"

 	"github.com/docker/docker/pkg/archive"

 	"github.com/docker/docker/pkg/system"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -227,7 +226,7 @@ func copyToContainer(ctx context.Context, dockerCli *command.DockerCli, srcPath,

 		content = os.Stdin

 		resolvedDstPath = dstInfo.Path

 		if !dstInfo.IsDir {

-			return fmt.Errorf("destination \"%s:%s\" must be a directory", dstContainer, dstPath)

+			return errors.Errorf("destination \"%s:%s\" must be a directory", dstContainer, dstPath)

 		}

 	} else {

 		// Prepare source copy info.

@@ -14,6 +14,7 @@ import (

 	apiclient "github.com/docker/docker/client"

 	"github.com/docker/docker/pkg/jsonmessage"

 	"github.com/docker/docker/registry"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"github.com/spf13/pflag"

 	"golang.org/x/net/context"

@@ -118,7 +119,7 @@ func (cid *cidFile) Close() error {

 		return nil

 	}

 	if err := os.Remove(cid.path); err != nil {

-		return fmt.Errorf("failed to remove the CID file '%s': %s \n", cid.path, err)

+		return errors.Errorf("failed to remove the CID file '%s': %s \n", cid.path, err)

 	}

 	return nil

@@ -126,7 +127,7 @@ func (cid *cidFile) Close() error {

 func (cid *cidFile) Write(id string) error {

 	if _, err := cid.file.Write([]byte(id)); err != nil {

-		return fmt.Errorf("Failed to write the container ID to the file: %s", err)

+		return errors.Errorf("Failed to write the container ID to the file: %s", err)

 	}

 	cid.written = true

 	return nil

@@ -134,12 +135,12 @@ func (cid *cidFile) Write(id string) error {

 func newCIDFile(path string) (*cidFile, error) {

 	if _, err := os.Stat(path); err == nil {

-		return nil, fmt.Errorf("Container ID file found, make sure the other container isn't running or delete %s", path)

+		return nil, errors.Errorf("Container ID file found, make sure the other container isn't running or delete %s", path)

 	}

 	f, err := os.Create(path)

 	if err != nil {

-		return nil, fmt.Errorf("Failed to create the container ID file: %s", err)

+		return nil, errors.Errorf("Failed to create the container ID file: %s", err)

 	}

 	return &cidFile{path: path, file: f}, nil

@@ -1,12 +1,12 @@

 package container

 import (

-	"errors"

 	"fmt"

 	"github.com/docker/docker/cli"

 	"github.com/docker/docker/cli/command"

 	"github.com/docker/docker/pkg/archive"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -1,11 +1,11 @@

 package container

 import (

-	"errors"

 	"io"

 	"github.com/docker/docker/cli"

 	"github.com/docker/docker/cli/command"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -1,12 +1,12 @@

 package container

 import (

-	"errors"

 	"fmt"

 	"strings"

 	"github.com/docker/docker/cli"

 	"github.com/docker/docker/cli/command"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -18,6 +18,7 @@ import (

 	"github.com/docker/docker/pkg/signal"

 	runconfigopts "github.com/docker/docker/runconfig/opts"

 	"github.com/docker/go-connections/nat"

+	"github.com/pkg/errors"

 	"github.com/spf13/pflag"

 )

@@ -301,7 +302,7 @@ func parse(flags *pflag.FlagSet, copts *containerOptions) (*containerConfig, err

 	// Validate the input mac address

 	if copts.macAddress != "" {

 		if _, err := opts.ValidateMACAddress(copts.macAddress); err != nil {

-			return nil, fmt.Errorf("%s is not a valid mac address", copts.macAddress)

+			return nil, errors.Errorf("%s is not a valid mac address", copts.macAddress)

 		}

 	}

 	if copts.stdin {

@@ -317,7 +318,7 @@ func parse(flags *pflag.FlagSet, copts *containerOptions) (*containerConfig, err

 	swappiness := copts.swappiness

 	if swappiness != -1 && (swappiness < 0 || swappiness > 100) {

-		return nil, fmt.Errorf("invalid value: %d. Valid memory swappiness range is 0-100", swappiness)

+		return nil, errors.Errorf("invalid value: %d. Valid memory swappiness range is 0-100", swappiness)

 	}

 	var binds []string

@@ -368,7 +369,7 @@ func parse(flags *pflag.FlagSet, copts *containerOptions) (*containerConfig, err

 	// Merge in exposed ports to the map of published ports

 	for _, e := range copts.expose.GetAll() {

 		if strings.Contains(e, ":") {

-			return nil, fmt.Errorf("invalid port format for --expose: %s", e)

+			return nil, errors.Errorf("invalid port format for --expose: %s", e)

 		}

 		//support two formats for expose, original format <portnum>/[<proto>] or <startport-endport>/[<proto>]

 		proto, port := nat.SplitProtoPort(e)

@@ -376,7 +377,7 @@ func parse(flags *pflag.FlagSet, copts *containerOptions) (*containerConfig, err

 		//if expose a port, the start and end port are the same

 		start, end, err := nat.ParsePortRange(port)

 		if err != nil {

-			return nil, fmt.Errorf("invalid range format for --expose: %s, error: %s", e, err)

+			return nil, errors.Errorf("invalid range format for --expose: %s, error: %s", e, err)

 		}

 		for i := start; i <= end; i++ {

 			p, err := nat.NewPort(proto, strconv.FormatUint(i, 10))

@@ -413,22 +414,22 @@ func parse(flags *pflag.FlagSet, copts *containerOptions) (*containerConfig, err

 	ipcMode := container.IpcMode(copts.ipcMode)

 	if !ipcMode.Valid() {

-		return nil, fmt.Errorf("--ipc: invalid IPC mode")

+		return nil, errors.Errorf("--ipc: invalid IPC mode")

 	}

 	pidMode := container.PidMode(copts.pidMode)

 	if !pidMode.Valid() {

-		return nil, fmt.Errorf("--pid: invalid PID mode")

+		return nil, errors.Errorf("--pid: invalid PID mode")

 	}

 	utsMode := container.UTSMode(copts.utsMode)

 	if !utsMode.Valid() {

-		return nil, fmt.Errorf("--uts: invalid UTS mode")

+		return nil, errors.Errorf("--uts: invalid UTS mode")

 	}

 	usernsMode := container.UsernsMode(copts.usernsMode)

 	if !usernsMode.Valid() {

-		return nil, fmt.Errorf("--userns: invalid USER mode")

+		return nil, errors.Errorf("--userns: invalid USER mode")

 	}

 	restartPolicy, err := runconfigopts.ParseRestartPolicy(copts.restartPolicy)

@@ -459,7 +460,7 @@ func parse(flags *pflag.FlagSet, copts *containerOptions) (*containerConfig, err

 		copts.healthRetries != 0

 	if copts.noHealthcheck {

 		if haveHealthSettings {

-			return nil, fmt.Errorf("--no-healthcheck conflicts with --health-* options")

+			return nil, errors.Errorf("--no-healthcheck conflicts with --health-* options")

 		}

 		test := strslice.StrSlice{"NONE"}

 		healthConfig = &container.HealthConfig{Test: test}

@@ -470,13 +471,13 @@ func parse(flags *pflag.FlagSet, copts *containerOptions) (*containerConfig, err

 			probe = strslice.StrSlice(args)

 		}

 		if copts.healthInterval < 0 {

-			return nil, fmt.Errorf("--health-interval cannot be negative")

+			return nil, errors.Errorf("--health-interval cannot be negative")

 		}

 		if copts.healthTimeout < 0 {

-			return nil, fmt.Errorf("--health-timeout cannot be negative")

+			return nil, errors.Errorf("--health-timeout cannot be negative")

 		}

 		if copts.healthRetries < 0 {

-			return nil, fmt.Errorf("--health-retries cannot be negative")

+			return nil, errors.Errorf("--health-retries cannot be negative")

 		}

 		healthConfig = &container.HealthConfig{

@@ -591,7 +592,7 @@ func parse(flags *pflag.FlagSet, copts *containerOptions) (*containerConfig, err

 	}

 	if copts.autoRemove && !hostConfig.RestartPolicy.IsNone() {

-		return nil, fmt.Errorf("Conflicting options: --restart and --rm")

+		return nil, errors.Errorf("Conflicting options: --restart and --rm")

 	}

 	// only set this value if the user provided the flag, else it should default to nil

@@ -653,7 +654,7 @@ func parse(flags *pflag.FlagSet, copts *containerOptions) (*containerConfig, err

 func parseLoggingOpts(loggingDriver string, loggingOpts []string) (map[string]string, error) {

 	loggingOptsMap := runconfigopts.ConvertKVStringsToMap(loggingOpts)

 	if loggingDriver == "none" && len(loggingOpts) > 0 {

-		return map[string]string{}, fmt.Errorf("invalid logging opts for driver %s", loggingDriver)

+		return map[string]string{}, errors.Errorf("invalid logging opts for driver %s", loggingDriver)

 	}

 	return loggingOptsMap, nil

 }

@@ -666,17 +667,17 @@ func parseSecurityOpts(securityOpts []string) ([]string, error) {

 			if strings.Contains(opt, ":") {

 				con = strings.SplitN(opt, ":", 2)

 			} else {

-				return securityOpts, fmt.Errorf("Invalid --security-opt: %q", opt)

+				return securityOpts, errors.Errorf("Invalid --security-opt: %q", opt)

 			}

 		}

 		if con[0] == "seccomp" && con[1] != "unconfined" {

 			f, err := ioutil.ReadFile(con[1])

 			if err != nil {

-				return securityOpts, fmt.Errorf("opening seccomp profile (%s) failed: %v", con[1], err)

+				return securityOpts, errors.Errorf("opening seccomp profile (%s) failed: %v", con[1], err)

 			}

 			b := bytes.NewBuffer(nil)

 			if err := json.Compact(b, f); err != nil {

-				return securityOpts, fmt.Errorf("compacting json for seccomp profile (%s) failed: %v", con[1], err)

+				return securityOpts, errors.Errorf("compacting json for seccomp profile (%s) failed: %v", con[1], err)

 			}

 			securityOpts[key] = fmt.Sprintf("seccomp=%s", b.Bytes())

 		}

@@ -693,7 +694,7 @@ func parseStorageOpts(storageOpts []string) (map[string]string, error) {

 			opt := strings.SplitN(option, "=", 2)

 			m[opt[0]] = opt[1]

 		} else {

-			return nil, fmt.Errorf("invalid storage option")

+			return nil, errors.Errorf("invalid storage option")

 		}

 	}

 	return m, nil

@@ -719,7 +720,7 @@ func parseDevice(device string) (container.DeviceMapping, error) {

 	case 1:

 		src = arr[0]

 	default:

-		return container.DeviceMapping{}, fmt.Errorf("invalid device specification: %s", device)

+		return container.DeviceMapping{}, errors.Errorf("invalid device specification: %s", device)

 	}

 	if dst == "" {

@@ -742,7 +743,7 @@ func validateDeviceCgroupRule(val string) (string, error) {

 		return val, nil

 	}

-	return val, fmt.Errorf("invalid device cgroup format '%s'", val)

+	return val, errors.Errorf("invalid device cgroup format '%s'", val)

 }

 // validDeviceMode checks if the mode for device is valid or not.

@@ -778,12 +779,12 @@ func validatePath(val string, validator func(string) bool) (string, error) {

 	var mode string

 	if strings.Count(val, ":") > 2 {

-		return val, fmt.Errorf("bad format for path: %s", val)

+		return val, errors.Errorf("bad format for path: %s", val)

 	}

 	split := strings.SplitN(val, ":", 3)

 	if split[0] == "" {

-		return val, fmt.Errorf("bad format for path: %s", val)

+		return val, errors.Errorf("bad format for path: %s", val)

 	}

 	switch len(split) {

 	case 1:

@@ -802,13 +803,13 @@ func validatePath(val string, validator func(string) bool) (string, error) {

 		containerPath = split[1]

 		mode = split[2]

 		if isValid := validator(split[2]); !isValid {

-			return val, fmt.Errorf("bad mode specified: %s", mode)

+			return val, errors.Errorf("bad mode specified: %s", mode)

 		}

 		val = fmt.Sprintf("%s:%s:%s", split[0], containerPath, mode)

 	}

 	if !path.IsAbs(containerPath) {

-		return val, fmt.Errorf("%s is not an absolute path", containerPath)

+		return val, errors.Errorf("%s is not an absolute path", containerPath)

 	}

 	return val, nil

 }

@@ -882,5 +883,5 @@ func validateAttach(val string) (string, error) {

 			return s, nil

 		}

 	}

-	return val, fmt.Errorf("valid streams are STDIN, STDOUT and STDERR")

+	return val, errors.Errorf("valid streams are STDIN, STDOUT and STDERR")

 }

@@ -16,6 +16,7 @@ import (

 	"github.com/docker/docker/pkg/testutil/assert"

 	"github.com/docker/docker/runconfig"

 	"github.com/docker/go-connections/nat"

+	"github.com/pkg/errors"

 	"github.com/spf13/pflag"

 )

@@ -224,7 +225,7 @@ func compareRandomizedStrings(a, b, c, d string) error {

 	if a == d && b == c {

 		return nil

 	}

-	return fmt.Errorf("strings don't match")

+	return errors.Errorf("strings don't match")

 }

 // Simple parse with MacAddress validation

@@ -751,14 +752,14 @@ func callDecodeContainerConfig(volumes []string, binds []string) (*container.Con

 		w.Config.Volumes[v] = struct{}{}

 	}

 	if b, err = json.Marshal(w); err != nil {

-		return nil, nil, fmt.Errorf("Error on marshal %s", err.Error())

+		return nil, nil, errors.Errorf("Error on marshal %s", err.Error())

 	}

 	c, h, _, err = runconfig.DecodeContainerConfig(bytes.NewReader(b))

 	if err != nil {

-		return nil, nil, fmt.Errorf("Error parsing %s: %v", string(b), err)

+		return nil, nil, errors.Errorf("Error parsing %s: %v", string(b), err)

 	}

 	if c == nil || h == nil {

-		return nil, nil, fmt.Errorf("Empty config or hostconfig")

+		return nil, nil, errors.Errorf("Empty config or hostconfig")

 	}

 	return c, h, err

@@ -1,12 +1,12 @@

 package container

 import (

-	"errors"

 	"fmt"

 	"strings"

 	"github.com/docker/docker/cli"

 	"github.com/docker/docker/cli/command"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -7,6 +7,7 @@ import (

 	"github.com/docker/docker/cli"

 	"github.com/docker/docker/cli/command"

 	"github.com/docker/go-connections/nat"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -64,7 +65,7 @@ func runPort(dockerCli *command.DockerCli, opts *portOptions) error {

 			}

 			return nil

 		}

-		return fmt.Errorf("Error: No public port '%s' published for %s", natPort, opts.container)

+		return errors.Errorf("Error: No public port '%s' published for %s", natPort, opts.container)

 	}

 	for from, frontends := range c.NetworkSettings.Ports {

@@ -1,12 +1,12 @@

 package container

 import (

-	"errors"

 	"fmt"

 	"strings"

 	"github.com/docker/docker/cli"

 	"github.com/docker/docker/cli/command"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -45,7 +45,7 @@ func runRename(dockerCli *command.DockerCli, opts *renameOptions) error {

 	if err := dockerCli.Client().ContainerRename(ctx, oldName, newName); err != nil {

 		fmt.Fprintln(dockerCli.Err(), err)

-		return fmt.Errorf("Error: failed to rename container named %s", oldName)

+		return errors.Errorf("Error: failed to rename container named %s", oldName)

 	}

 	return nil

 }

@@ -1,13 +1,13 @@

 package container

 import (

-	"errors"

 	"fmt"

 	"strings"

 	"time"

 	"github.com/docker/docker/cli"

 	"github.com/docker/docker/cli/command"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -1,13 +1,13 @@

 package container

 import (

-	"errors"

 	"fmt"

 	"strings"

 	"github.com/docker/docker/api/types"

 	"github.com/docker/docker/cli"

 	"github.com/docker/docker/cli/command"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -1,7 +1,6 @@

 package container

 import (

-	"errors"

 	"fmt"

 	"io"

 	"net/http/httputil"

@@ -18,6 +17,7 @@ import (

 	"github.com/docker/docker/pkg/promise"

 	"github.com/docker/docker/pkg/signal"

 	"github.com/docker/libnetwork/resolvconf/dns"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"github.com/spf13/pflag"

 	"golang.org/x/net/context"

@@ -1,7 +1,6 @@

 package container

 import (

-	"errors"

 	"fmt"

 	"io"

 	"net/http/httputil"

@@ -12,6 +11,7 @@ import (

 	"github.com/docker/docker/cli/command"

 	"github.com/docker/docker/pkg/promise"

 	"github.com/docker/docker/pkg/signal"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -173,7 +173,7 @@ func startContainersWithoutAttachments(ctx context.Context, dockerCli *command.D

 	}

 	if len(failedContainers) > 0 {

-		return fmt.Errorf("Error: failed to start containers: %s", strings.Join(failedContainers, ", "))

+		return errors.Errorf("Error: failed to start containers: %s", strings.Join(failedContainers, ", "))

 	}

 	return nil

 }

@@ -1,7 +1,6 @@

 package container

 import (

-	"errors"

 	"fmt"

 	"io"

 	"strings"

@@ -14,6 +13,7 @@ import (

 	"github.com/docker/docker/cli"

 	"github.com/docker/docker/cli/command"

 	"github.com/docker/docker/cli/command/formatter"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -2,7 +2,6 @@ package container

 import (

 	"encoding/json"

-	"errors"

 	"io"

 	"strings"

 	"sync"

@@ -12,6 +11,7 @@ import (

 	"github.com/docker/docker/api/types"

 	"github.com/docker/docker/cli/command/formatter"

 	"github.com/docker/docker/client"

+	"github.com/pkg/errors"

 	"golang.org/x/net/context"

 )

@@ -1,13 +1,13 @@

 package container

 import (

-	"errors"

 	"fmt"

 	"strings"

 	"time"

 	"github.com/docker/docker/cli"

 	"github.com/docker/docker/cli/command"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -1,12 +1,12 @@

 package container

 import (

-	"errors"

 	"fmt"

 	"strings"

 	"github.com/docker/docker/cli"

 	"github.com/docker/docker/cli/command"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -1,7 +1,6 @@

 package container

 import (

-	"errors"

 	"fmt"

 	"strings"

@@ -10,6 +9,7 @@ import (

 	"github.com/docker/docker/cli/command"

 	"github.com/docker/docker/opts"

 	runconfigopts "github.com/docker/docker/runconfig/opts"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -1,12 +1,12 @@

 package container

 import (

-	"errors"

 	"fmt"

 	"strings"

 	"github.com/docker/docker/cli"

 	"github.com/docker/docker/cli/command"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -2,13 +2,13 @@ package formatter

 import (

 	"bytes"

-	"fmt"

 	"io"

 	"strings"

 	"text/tabwriter"

 	"text/template"

 	"github.com/docker/docker/pkg/templates"

+	"github.com/pkg/errors"

 )

 // Format keys used to specify certain kinds of output formats

@@ -64,7 +64,7 @@ func (c *Context) preFormat() {

 func (c *Context) parseFormat() (*template.Template, error) {

 	tmpl, err := templates.Parse(c.finalFormat)

 	if err != nil {

-		return tmpl, fmt.Errorf("Template parsing error: %v\n", err)

+		return tmpl, errors.Errorf("Template parsing error: %v\n", err)

 	}

 	return tmpl, err

 }

@@ -85,7 +85,7 @@ func (c *Context) postFormat(tmpl *template.Template, subContext subContext) {

 func (c *Context) contextFormat(tmpl *template.Template, subContext subContext) error {

 	if err := tmpl.Execute(c.buffer, subContext); err != nil {

-		return fmt.Errorf("Template parsing error: %v\n", err)

+		return errors.Errorf("Template parsing error: %v\n", err)

 	}

 	if c.Format.IsTable() && c.header != nil {

 		c.header = subContext.FullHeader()

@@ -2,9 +2,10 @@ package formatter

 import (

 	"encoding/json"

-	"fmt"

 	"reflect"

 	"unicode"

+

+	"github.com/pkg/errors"

 )

 func marshalJSON(x interface{}) ([]byte, error) {

@@ -19,14 +20,14 @@ func marshalJSON(x interface{}) ([]byte, error) {

 func marshalMap(x interface{}) (map[string]interface{}, error) {

 	val := reflect.ValueOf(x)

 	if val.Kind() != reflect.Ptr {

-		return nil, fmt.Errorf("expected a pointer to a struct, got %v", val.Kind())

+		return nil, errors.Errorf("expected a pointer to a struct, got %v", val.Kind())

 	}

 	if val.IsNil() {

-		return nil, fmt.Errorf("expected a pointer to a struct, got nil pointer")

+		return nil, errors.Errorf("expected a pointer to a struct, got nil pointer")

 	}

 	valElem := val.Elem()

 	if valElem.Kind() != reflect.Struct {

-		return nil, fmt.Errorf("expected a pointer to a struct, got a pointer to %v", valElem.Kind())

+		return nil, errors.Errorf("expected a pointer to a struct, got a pointer to %v", valElem.Kind())

 	}

 	typ := val.Type()

 	m := make(map[string]interface{})

@@ -48,7 +49,7 @@ var unmarshallableNames = map[string]struct{}{"FullHeader": {}}

 // It returns ("", nil, nil) for valid but non-marshallable parameter. (e.g. "unexportedFunc()")

 func marshalForMethod(typ reflect.Method, val reflect.Value) (string, interface{}, error) {

 	if val.Kind() != reflect.Func {

-		return "", nil, fmt.Errorf("expected func, got %v", val.Kind())

+		return "", nil, errors.Errorf("expected func, got %v", val.Kind())

 	}

 	name, numIn, numOut := typ.Name, val.Type().NumIn(), val.Type().NumOut()

 	_, blackListed := unmarshallableNames[name]

@@ -1,7 +1,6 @@

 package formatter

 import (

-	"fmt"

 	"strings"

 	"time"

@@ -11,6 +10,7 @@ import (

 	"github.com/docker/docker/cli/command/inspect"

 	"github.com/docker/docker/pkg/stringid"

 	units "github.com/docker/go-units"

+	"github.com/pkg/errors"

 )

 const serviceInspectPrettyTemplate Format = `

@@ -147,7 +147,7 @@ func ServiceInspectWrite(ctx Context, refs []string, getRef inspect.GetRefFunc)

 			}

 			service, ok := serviceI.(swarm.Service)

 			if !ok {

-				return fmt.Errorf("got wrong object to inspect")

+				return errors.Errorf("got wrong object to inspect")

 			}

 			if err := format(&serviceInspectContext{Service: service}); err != nil {

 				return err

@@ -1,12 +1,11 @@

 package idresolver

 import (

-	"fmt"

-

 	"golang.org/x/net/context"

 	"github.com/docker/docker/api/types/swarm"

 	"github.com/docker/docker/client"

+	"github.com/pkg/errors"

 )

 // IDResolver provides ID to Name resolution.

@@ -46,7 +45,7 @@ func (r *IDResolver) get(ctx context.Context, t interface{}, id string) (string,

 		}

 		return service.Spec.Annotations.Name, nil

 	default:

-		return "", fmt.Errorf("unsupported type")

+		return "", errors.Errorf("unsupported type")

 	}

 }

@@ -28,6 +28,7 @@ import (

 	"github.com/docker/docker/pkg/urlutil"

 	runconfigopts "github.com/docker/docker/runconfig/opts"

 	units "github.com/docker/go-units"

+	"github.com/pkg/errors"

 	"github.com/spf13/cobra"

 	"golang.org/x/net/context"

 )

@@ -166,14 +167,14 @@ func runBuild(dockerCli *command.DockerCli, options buildOptions) error {

 	case urlutil.IsURL(specifiedContext):

 		buildCtx, relDockerfile, err = build.GetContextFromURL(progBuff, specifiedContext, options.dockerfileName)

 	default:

-		return fmt.Errorf("unable to prepare context: path %q not found", specifiedContext)

+		return errors.Errorf("unable to prepare context: path %q not found", specifiedContext)

 	}

 	if err != nil {

 		if options.quiet && urlutil.IsURL(specifiedContext) {

 			fmt.Fprintln(dockerCli.Err(), progBuff)

 		}

-		return fmt.Errorf("unable to prepare context: %s", err)

+		return errors.Errorf("unable to prepare context: %s", err)

 	}

 	if tempDir != "" {

@@ -185,7 +186,7 @@ func runBuild(dockerCli *command.DockerCli, options buildOptions) error {

 		// And canonicalize dockerfile name to a platform-independent one

 		relDockerfile, err = archive.CanonicalTarNameForPath(relDockerfile)

 		if err != nil {

-			return fmt.Errorf("cannot canonicalize dockerfile path %s: %v", relDockerfile, err)

+			return errors.Errorf("cannot canonicalize dockerfile path %s: %v", relDockerfile, err)

 		}

 		f, err := os.Open(filepath.Join(contextDir, ".dockerignore"))

@@ -203,7 +204,7 @@ func runBuild(dockerCli *command.DockerCli, options buildOptions) error {

 		}

 		if err := build.ValidateContextDirectory(contextDir, excludes); err != nil {

-			return fmt.Errorf("Error checking context: '%s'.", err)

+			return errors.Errorf("Error checking context: '%s'.", err)

 		}

 		// If .dockerignore mentions .dockerignore or the Dockerfile

@@ -18,6 +18,7 @@ import (

 	"github.com/docker/docker/pkg/ioutils"

 	"github.com/docker/docker/pkg/progress"

 	"github.com/docker/docker/pkg/streamformatter"

+	"github.com/pkg/errors"

 )

 const (

@@ -36,7 +37,7 @@ func ValidateContextDirectory(srcPath string, excludes []string) error {

 	return filepath.Walk(contextRoot, func(filePath string, f os.FileInfo, err error) error {

 		if err != nil {

 			if os.IsPermission(err) {

-				return fmt.Errorf("can't stat '%s'", filePath)

+				return errors.Errorf("can't stat '%s'", filePath)

 			}

 			if os.IsNotExist(err) {

 				return nil

@@ -65,7 +66,7 @@ func ValidateContextDirectory(srcPath string, excludes []string) error {

 		if !f.IsDir() {

 			currentFile, err := os.Open(filePath)

 			if err != nil && os.IsPermission(err) {

-				return fmt.Errorf("no permission to read from '%s'", filePath)

+				return errors.Errorf("no permission to read from '%s'", filePath)

 			}

 			currentFile.Close()

 		}

@@ -81,7 +82,7 @@ func GetContextFromReader(r io.ReadCloser, dockerfileName string) (out io.ReadCl

 	magic, err := buf.Peek(archive.HeaderSize)

 	if err != nil && err != io.EOF {

-		return nil, "", fmt.Errorf("failed to peek context header from STDIN: %v", err)