1. docker
  2. Commit b86e3bee5aea8e72b7f08e104ebb5d6cb18f8890
Browse code

gcplogs: forcibly set HOME on static UNIX binary

Fix #29344

If HOME is not set, the gcplogs logging driver will call os/user.Current() via oauth2/google.
However, in static binary, os/user.Current() leads to segfault due to a glibc issue that won't be fixed
in a short term. (golang/go#13470, https://sourceware.org/bugzilla/show_bug.cgi?id=19341)
So we forcibly set HOME so as to avoid call to os/user/Current().

Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>

Akihiro Suda authored on 2016/12/16 18:50:14
Showing 5 changed files
daemon/logger/gcplogs/gcplogging.go
History View file @ b86e3be
... ... 
@@ -114,6 +114,15 @@ func New(ctx logger.Context) (logger.Logger, error) {
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 		return nil, fmt.Errorf("No project was specified and couldn't read project from the meatadata server. Please specify a project")
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 	}
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+	// Issue #29344: gcplogs segfaults (static binary)
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+	// If HOME is not set, logging.NewClient() will call os/user.Current() via oauth2/google.
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+	// However, in static binary, os/user.Current() leads to segfault due to a glibc issue that won't be fixed
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+	// in a short term. (golang/go#13470, https://sourceware.org/bugzilla/show_bug.cgi?id=19341)
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+	// So we forcibly set HOME so as to avoid call to os/user/Current()
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+	if err := ensureHomeIfIAmStatic(); err != nil {
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+		return nil, err
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+	}
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+
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 	c, err := logging.NewClient(context.Background(), project)
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 	if err != nil {
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 		return nil, err
daemon/logger/gcplogs/gcplogging_linux.go
History View file @ b86e3be
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new file mode 100644
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@@ -0,0 +1,31 @@
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+// +build linux
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+
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+package gcplogs
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+
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+import (
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+	"os"
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+
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+	"github.com/Sirupsen/logrus"
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+	"github.com/docker/docker/dockerversion"
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+	"github.com/docker/docker/pkg/homedir"
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+)
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+
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+// ensureHomeIfIAmStatic ensure $HOME to be set if dockerversion.IAmStatic is "true".
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+// See issue #29344: gcplogs segfaults (static binary)
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+// If HOME is not set, logging.NewClient() will call os/user.Current() via oauth2/google.
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+// However, in static binary, os/user.Current() leads to segfault due to a glibc issue that won't be fixed
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+// in a short term. (golang/go#13470, https://sourceware.org/bugzilla/show_bug.cgi?id=19341)
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+// So we forcibly set HOME so as to avoid call to os/user/Current()
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+func ensureHomeIfIAmStatic() error {
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+	// Note: dockerversion.IAmStatic and homedir.GetStatic() is only available for linux.
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+	// So we need to use them in this gcplogging_linux.go rather than in gcplogging.go
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+	if dockerversion.IAmStatic == "true" && os.Getenv("HOME") == "" {
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+		home, err := homedir.GetStatic()
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+		if err != nil {
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+			return err
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+		}
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+		logrus.Warnf("gcplogs requires HOME to be set for static daemon binary. Forcibly setting HOME to %s.", home)
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+		os.Setenv("HOME", home)
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+	}
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+	return nil
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+}
daemon/logger/gcplogs/gcplogging_others.go
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@@ -0,0 +1,7 @@
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+// +build !linux
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+
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+package gcplogs
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+
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+func ensureHomeIfIAmStatic() error {
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+	return nil
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+}
pkg/homedir/homedir_linux.go
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+// +build linux
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+
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+package homedir
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+
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+import (
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+	"os"
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+
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+	"github.com/docker/docker/pkg/idtools"
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+)
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+
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+// GetStatic returns the home directory for the current user without calling
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+// os/user.Current(). This is useful for static-linked binary on glibc-based
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+// system, because a call to os/user.Current() in a static binary leads to
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+// segfault due to a glibc issue that won't be fixed in a short term.
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+// (#29344, golang/go#13470, https://sourceware.org/bugzilla/show_bug.cgi?id=19341)
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+func GetStatic() (string, error) {
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+	uid := os.Getuid()
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+	usr, err := idtools.LookupUID(uid)
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+	if err != nil {
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+		return "", err
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+	}
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+	return usr.Home, nil
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+}
pkg/homedir/homedir_others.go
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+// +build !linux
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+
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+package homedir
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+
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+import (
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+	"errors"
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+)
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+
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+// GetStatic is not needed for non-linux systems.
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+// (Precisely, it is needed only for glibc-based linux systems.)
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+func GetStatic() (string, error) {
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+	return "", errors.New("homedir.GetStatic() is not supported on this system")
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+}