docker-compose exec时出现"fork/exec /proc/self/exe: no such file or directory" 报错

问题：跟往常一样执行docker-compos exec redis sh时出现如下错误，而容器是运行状态中。

# docker-compose exec redis sh
rpc error: code = 2 desc = oci runtime error: exec failed: container_linux.go:247: starting container process caused "process_linux.go:75: starting setns process caused "fork/exec /proc/self/exe: no such file or directory""

解决办法：

1、获取容器ID

# docker ps | grep arcs_redis_1
ac248a3c5c0e        redis:alpine                 "docker-entrypoint..."   2 years ago         Up 16 minutes                   6379/tcp                                                                                                                                          arcs_redis_1

2、通过容器ID获取容器的PID

# ps -ef|grep libcontainerd | grep ac248a3c5c0e
root      6650  9053  0 11:14 ?        00:00:00 docker-containerd-shim ac248a3c5c0e3f6405c35e186b5d095aeb7af72b0f52bb08303baded251cdb61 /var/run/docker/libcontainerd/ac248a3c5c0e3f6405c35e186b5d095aeb7af72b0f52bb08303baded251cdb61 docker-runc

注：第二个字段为容器的PID

3、获取容器的mount位置

# grep "path" /var/run/docker/libcontainerd/ac248a3c5c0e3f6405c35e186b5d095aeb7af72b0f52bb08303baded251cdb61/config.json

注：mount的路径：{"path":"/var/lib/docker/devicemapper/mnt/cc2ff9576cdf7736acca50ffdaadef471e01a8ffe9acb039c1d423edd941bd38/rootfs"}，此路径用于第6步挂载时使用。

４、用nsenter进入容器的namespace

# nsenter -m -t 6650 bash
注: 6650是容器的PID

5、查看容器的DeviceName

＃ docker inspect --format='{{.GraphDriver.Data.DeviceName}}' ac248a3c5c0e       ####ac248a3c5c0e是容器ID

docker-252:0-9700888-cc2ff9576cdf7736acca50ffdaadef471e01a8ffe9acb039c1d423edd941bd38

6、手动挂载

# mount /dev/mapper/docker-252:0-9700888-cc2ff9576cdf7736acca50ffdaadef471e01a8ffe9acb039c1d423edd941bd38 -o rw,relatime,nouuid,attr2,inode64,sunit=512,swidth=1024,noquota -t xfs /var/lib/docker/devicemapper/mnt/cc2ff9576cdf7736acca50ffdaadef471e01a8ffe9acb039c1d423edd941bd38

７、退出

＃exit

 8、再次执行docker-compose exec redis sh 无报错。

 说明：此报错是由于mount挂载点丢失，具体原因目前还未知晓，若有知晓者欢迎告知！