运行环境
OS：Win10 1909（内部版本18363.481）
WSL：1
Linux Distribution：Ubuntu 20.04
docker：20.10.6
错误信息
查看本地docker镜像时提示：
root@localhost:~# docker images
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?
解决办法
- 首先确认是否启动了docker
root@localhost:~# ps -ef | grep docker
root 39 10 0 14:17 pts/0 00:00:00 grep --color=auto docker
如上图所示，就是docker没有启动，使用如下命令启动docker后：
root@localhost:~# service docker start
* Starting Docker: docker [OK]
重新检查docker进程是否存在：
root@localhost:~# ps -ef | grep docker
root 90 9 0 14:21 ? 00:00:00 /usr/bin/dockerd -p /var/run/docker.pid
root 105 90 0 14:21 ? 00:00:00 containerd --config /var/run/docker/containerd/containerd.toml --log-level info
root 247 10 0 14:22 pts/0 00:00:00 grep --color=auto docker
如上信息表示docker已成功启动。
- 如果docker未能启动成功，查看docker启动日志
/var/log/docker.log（Ubuntu），如果日志末尾是如下错误信息：
time="2021-05-31T20:44:03.396093900+08:00" level=warning msg="Running iptables --wait -t nat -L -n failed with message: `iptables v1.8.4 (legacy): can't initialize iptables table `nat': Table does not exist (do you need to insmod?)\nPerhaps iptables or your kernel needs to be upgraded.`, error: exit status 3"
time="2021-05-31T20:44:03.632996500+08:00" level=info msg="stopping event stream following graceful shutdown" error="<nil>" module=libcontainerd namespace=moby
time="2021-05-31T20:44:03.633028700+08:00" level=info msg="stopping event stream following graceful shutdown" error="context canceled" module=libcontainerd namespace=plugins.moby
time="2021-05-31T20:44:03.633035700+08:00" level=info msg="stopping healthcheck following graceful shutdown" module=libcontainerd
time="2021-05-31T20:44:04.633797400+08:00" level=warning msg="grpc: addrConn.createTransport failed to connect to {unix:///var/run/docker/containerd/containerd.sock <nil> 0 <nil>}. Err :connection error: desc = \"transport: Error while dialing dial unix:///var/run/docker/containerd/containerd.sock: timeout\". Reconnecting..." module=grpc
failed to start daemon: Error initializing network controller: error obtaining controller instance: failed to create NAT chain DOCKER: iptables failed: iptables -t nat -N DOCKER: iptables v1.8.4 (legacy): can't initialize iptables table `nat': Table does not exist (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.
(exit status 3)
则需要将WSL1升级为WSL2，升级更新操作可以参考在Win10中安装Ubuntu中的“更新到WSL 2”章节。
