1、docker-compose启的nexus仓库意外dead
公司的maven私服nexus是通过docker-compose启动的，不知道什么原因意外死掉了。再次启动的时候报错：
[root@test-java nexus]# docker-compose up -d
Removing nexus_nexus_1
ERROR: driver "overlay" failed to remove root filesystem for 738f492a57f80951b279c3bd82f59b6230275a298ab74d7f26c4564cf3d1cf2c: remove /var/lib/docker/overlay/6031651302dba6053c5fde07937f4fd00dfc063577fa343b12c83f1c26b77887/merged: device or resource busy
2、原因分析
看报错应该是之前的容器无法删除导致的，device or resource busy应该是还有某些进程在占用。
3、处理问题
先通过docker rm命令尝试删除该容器：
[root@test-java nexus]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
141d9363cf95 jenkins "/bin/tini -- /usr..." 12 days ago Exited (137) 10 days ago jenkins
85e5f06d1344 jenkins "/bin/tini -- /usr..." 12 days ago Exited (130) 12 days ago reverent_ritchie
738f492a57f8 sonatype/nexus3 "bin/nexus run" 2 weeks ago Dead nexus_nexus_1
eef939679dd1 nginx:1.13.3 "/usr/local/nginx/..." 2 months ago Created 443/tcp, 0.0.0.0:8087->80/tcp nginx2
5087229bf9aa nginx:1.13.3 "/usr/local/nginx/..." 2 months ago Exited (0) 2 weeks ago nginx
c67cf4bdefd9 sonatype/nexus3 "bin/nexus run" 9 months ago Dead c67cf4bdefd9_nexus_nexus_1
[root@test-java nexus]# docker rm 738f492a57f8
Error response from daemon: driver "overlay" failed to remove root filesystem for 738f492a57f80951b279c3bd82f59b6230275a298ab74d7f26c4564cf3d1cf2c: remove /var/lib/docker/overlay/6031651302dba6053c5fde07937f4fd00dfc063577fa343b12c83f1c26b77887/merged: device or resource busy
无法正常删除，尝试强制删除：
[root@test-java nexus]# docker rm -f 738f492a57f8
Error response from daemon: driver "overlay" failed to remove root filesystem for 738f492a57f80951b279c3bd82f59b6230275a298ab74d7f26c4564cf3d1cf2c: remove /var/lib/docker/overlay/6031651302dba6053c5fde07937f4fd00dfc063577fa343b12c83f1c26b77887/merged: device or resource busy
通过docker rm无法删除，提示文件系统相关的问题，应该是和docker容器的文件系统有关，docker是通过挂载的形式使用宿主机文件系统的。查看一下跟报错有关的挂载信息：
[root@test-java nexus]# grep docker /proc/*/mountinfo|grep 6031651302dba6053c5fde07937f4fd00dfc063577fa343b12c83f1c26b77887
/proc/814/mountinfo:80 79 0:38 / /var/lib/docker/overlay/6031651302dba6053c5fde07937f4fd00dfc063577fa343b12c83f1c26b77887/merged rw,relatime - overlay overlay rw,lowerdir=/var/lib/docker/overlay/e580d619ecdb1aeb01f73ad07d727812a3f9776af5af0679eecfd60198884aaf/root,upperdir=/var/lib/docker/overlay/6031651302dba6053c5fde07937f4fd00dfc063577fa343b12c83f1c26b77887/upper,workdir=/var/lib/docker/overlay/6031651302dba6053c5fde07937f4fd00dfc063577fa343b12c83f1c26b77887/work
注意：
6031651302dba6053c5fde07937f4fd00dfc063577fa343b12c83f1c26b77887这串数字是和报错中的一致的。
可以看到有跟该容器相关的挂载信息仍然处于挂载中，所以导致无法删除。
获取该挂载进程的pid并杀掉该进程：
[root@test-java nexus]# grep docker /proc/*/mountinfo|grep 6031651302dba6053c5fde07937f4fd00dfc063577fa343b12c83f1c26b77887 | awk -F ":" '{print $1}' | awk -F "/" '{print $3}'
814
[root@test-java nexus]# kill -9 814
重新启动nexus：
[root@test-java nexus]# docker-compose up -d
Removing nexus_nexus_1
Recreating c67cf4bdefd9_nexus_nexus_1 ... error
ERROR: for c67cf4bdefd9_nexus_nexus_1 b'driver "overlay" failed to remove root filesystem for c67cf4bdefd9746ab850d09960211b02d0d184aa5e7c602095b1acdee57dc813: remove /var/lib/docker/overlay/ec743b1c55a524fd85421621314aa5acd44a29601f917f1f2eaed5f1a6d6c727/merged: device or resource busy'
ERROR: for nexus b'driver "overlay" failed to remove root filesystem for c67cf4bdefd9746ab850d09960211b02d0d184aa5e7c602095b1acdee57dc813: remove /var/lib/docker/overlay/ec743b1c55a524fd85421621314aa5acd44a29601f917f1f2eaed5f1a6d6c727/merged: device or resource busy'
ERROR: Encountered errors while bringing up the project.
还有这样的报错，说明还有相关的挂载进程没有停止掉。找出进程并杀掉：
[root@test-java nexus]# grep docker /proc/*/mountinfo|grep ec743b1c55a524fd85421621314aa5acd44a29601f917f1f2eaed5f1a6d6c727 | awk -F ":" '{print $1}' | awk -F "/" '{print $3}'
20910
21073
[root@test-java nexus]# kill -9 20910
[root@test-java nexus]# kill -9 21073
-bash: kill: (21073) - No such process
再次启动：
[root@test-java nexus]# docker-compose up -d
Removing nexus_nexus_1
Recreating c67cf4bdefd9_nexus_nexus_1 ... done
[root@test-java nexus]#
启动成功！