docker常见问题修复方法

一、运行容器报错：Error response from daemon: Error running DeviceCreate (createSnapDevice) dm_task_run failed

解决：

metadata目录在 docker info查看

service docker stop
thin_check /var/lib/docker/devicemapper/devicemapper/metadata
thin_check --clear-needs-check-flag /var/lib/docker/devicemapper/devicemapper/metadata
service docker start

二、Error running DeviceCreate (ActivateDevice) dm_task_run failed

重启docker服务器后 遇到 ‘device or resource busy’错误
如果有container在运行的时候重启 docker 服务， 可能会导致 container无法启动， 错误信息类似于：

Error response from daemon: Cannot start container zookeeper: Error
getting container
ddf1dd91bbf46dc648268327f8f7c6fffaf2f19cda5cf1d97fdc701016d4332c from
driver devicemapper: Error mounting
'/dev/mapper/docker-8:1-525372-ddf1dd91bbf46dc648268327f8f7c6fffaf2f19cda5cf1d97fdc701016d4332c'
on
'/var/lib/docker/devicemapper/mnt/ddf1dd91bbf46dc648268327f8f7c6fffaf2f19cda5cf1d97fdc701016d4332c':
device or resource busy 2015/01/26 04:42:07 Error: failed to start one
or more containers

或者：

d2859bd1f84b: Error pulling image (latest) from xxxxxx, Driver
devicemapper failed to create image rootfs
e6158e7962db43274de40fc3db65ad64811d43fe342dea633df20639f5a4e3cd: device
e6158e7962db43274de40fc3db65ad64811d43fe342dea633df20639f5a4e3cd
already exists 43fe342dea633df20639f5a4e3cd already exists c049b2b:
Download complete e6158e7962db: Error downloading dependent layers

解决：

这是一个Docker的 bug ，解决方式是先找出没有umount的路径

cat /proc/mounts | grep "mapper/docker" | awk '{print $2}'
然后依次
umount

三、[8] System error: fork/exec /usr/bin/docker: cannot allocate memory问题

The fix for me was to add swapspace. By default my digitalocean droplet didn’t come with any swap!

dd if=/dev/zero of=/root/myswapfile bs=1M count=1024
chmod 600 /root/myswapfile
mkswap -f /root/myswapfile
swapon /root/myswapfile

四、 防火墙变动异常

一般异常为：

Error response from daemon: Cannot start container web: iptables failed: iptables -t nat -A DOCKER -p tcp -d 0/0 --dport 32797 -j DNAT --to-destination 172.17.0.30:5000 ! -i docker0: iptables: No chain/target/match by that name.

解决办法：重建docker0网络恢复：

关闭当前防火墙

service iptables stop
重启docker重新建立防火墙规则
service docker restart
根据需求启停容器
docker restart[stop] 容器号