如何在Docker中成功启用udev同步?
我已经下载并安装静态链接从这个sitedocker 1.6.1
,并在RHEL 7.1
运行:如何在Docker中成功启用udev同步?
[[email protected] bin]# ./docker -d
WARN[0000] Udev sync is not supported. This will lead to unexpected behavior, data loss and errors
INFO[0000] +job init_networkdriver()
INFO[0000] +job serveapi(unix:///var/run/docker.sock)
INFO[0000] Listening for HTTP on unix (/var/run/docker.sock)
INFO[0000] -job init_networkdriver() = OK (0)
INFO[0000] Loading containers: start.
INFO[0000] Loading containers: done.
INFO[0000] docker daemon: 1.6.1 97cd073; execdriver: native-0.2; graphdriver: devicemapper
INFO[0000] +job acceptconnections()
INFO[0000] -job acceptconnections() = OK (0)
INFO[0000] Daemon has completed initialization
我可以看到有一个警告:“Udev sync is not supported. This will lead to unexpected behavior, data loss and errors
”,并检查docker
源代码后,我找到警告日志是deviceset.go:
func (devices *DeviceSet) initDevmapper(doInit bool) error {
......
// https://github.com/docker/docker/issues/4036
if supported := devicemapper.UdevSetSyncSupport(true); !supported {
log.Warnf("Udev sync is not supported. This will lead to unexpected behavior, data loss and errors")
}
log.Debugf("devicemapper: udev sync support: %v", devicemapper.UdevSyncSupported())
......
}
的devicemapper.UdevSetSyncSupport
是这样的:
// UdevSyncSupported returns whether device-mapper is able to sync with udev
//
// This is essential otherwise race conditions can arise where both udev and
// device-mapper attempt to create and destroy devices.
func UdevSyncSupported() bool {
return DmUdevGetSyncSupport() != 0
}
// UdevSetSyncSupport allows setting whether the udev sync should be enabled.
// The return bool indicates the state of whether the sync is enabled.
func UdevSetSyncSupport(enable bool) bool {
if enable {
DmUdevSetSyncSupport(1)
} else {
DmUdevSetSyncSupport(0)
}
return UdevSyncSupported()
}
我可以看到原因是启用udev
同步失败。如何才能使udev
同步成功?
更新: 检查dm_udev_set_sync_support
的反汇编代码后:
(gdb) disassemble dm_udev_set_sync_support
Dump of assembler code for function dm_udev_set_sync_support:
=> 0x0000000000a3e4e0 <+0>: repz retq
End of assembler dump.
这是一个空的功能,什么都不做,没有提及设置同步支持。这是否意味着这个静态构建的docker二进制文件是没有用的?
我无法重现您的问题;我收到以下内容:
(gdb) disassemble dm_udev_set_sync_support
Dump of assembler code for function [email protected]:
0x0000000000403420 <+0>: jmpq *0xda8c92(%rip) # 0x11ac0b8 <[email protected]>
0x0000000000403426 <+6>: pushq $0x14
0x000000000040342b <+11>: jmpq 0x4032d0
请帮忙:忽略docker.io的构建,并直接从RHEL获取Docker。它在“额外”频道中可用。虽然它通常会比上游版本落后几周(例如1.6而不是1.7),但它也经过充分测试并保证实际工作。
修订我原来的答复了一些有用的反馈后:
你必须使用一个动态二进制: “当然是与一个静态链接二进制,udev的同步是不可能的,因为这样可能会导致腐败问题问题 对于RedHat(维护devicemapper驱动程序)来说,这很困难,因为它们使用动态链接二进制文件(它们在其回收站中提供)。
刚刚1.7.0发行版时,docker开始提供rpms和debs与来自主要安装脚本@ get.docker.com的动态链接二进制文件(和易于回收以匹配)。 这些二进制文件支持udev sync,并且devicemapper应该可以正常工作。“
幸运的是,自创建OP以来,Docker已经更改了其存储库以提供动态二进制文件。参考:https://github.com/docker/docker/issues/13179