再谈docker基本命令

子曰，温故而知新

今日，再次看书之际，又寻得docker的几条使用命令，用小本本记下来

配置docker镜像源

当我们在拉去一些共有镜像时，默认,docker会向docker.io去获取，如果在拉取的过程中出现下载速度慢的情况呢，其实可以试试用一些国内的镜像源，例如:daocloud镜像站
官方文档: https://www.daocloud.io/mirror
仅需要一条明明足以

curl -sSL https://get.daocloud.io/daotools/set_mirror.sh | sh -s http://f1361db2.m.daocloud.io

当前命令适用于Ubuntu14.04、Debian、CentOS6 、CentOS7、Fedora、Arch Linux、openSUSE Leap 42.1
执行完毕后，需要重启一下docker

# systemctl restart docker

如果在重启的过程中报错:

Apr 20 09:02:48 localhost systemd: Starting Docker Application Container Engine...
Apr 20 09:02:48 localhost dockerd-current: unable to configure the Docker daemon with file /etc/docker/daemon.json: invalid character '}' looking for beginning of object key string
Apr 20 09:02:48 localhost systemd: docker.service: main process exited, code=exited, status=1/FAILURE

这是由于配置json文档的格式出错了

，则需要将/etc/docker/daemon.json文件中后面那个,号给删掉即可，例如

修改前:

{"registry-mirrors": ["http://f8214db2.m.daocloud.io"],}

修改后:

{"registry-mirrors": ["http://f8214db2.m.daocloud.io"]}

再次重启docker即可

查看docker 最新的log
使用docker logs -ft 即可
-f: 动态输出
-t: 增加时间戳
--tail n: 获取最新输出的n条
例如：

# docker logs -ft --tail 10 centos_name_1 
2019-04-20T13:27:19.366905000Z 
2019-04-20T13:27:19.368079000Z lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
2019-04-20T13:27:19.368478000Z inet 127.0.0.1 netmask 255.0.0.0
2019-04-20T13:27:19.368746000Z inet6 ::1 prefixlen 128 scopeid 0x10<host>
2019-04-20T13:27:19.369000000Z loop txqueuelen 1000 (Local Loopback)
2019-04-20T13:27:19.371869000Z RX packets 0 bytes 0 (0.0 B)
2019-04-20T13:27:19.374114000Z RX errors 0 dropped 0 overruns 0 frame 0
2019-04-20T13:27:19.374525000Z TX packets 0 bytes 0 (0.0 B)
2019-04-20T13:27:19.374886000Z TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
2019-04-20T13:27:19.375426000Z

查看docker进程
使用docker top命令可以查看docker中的进程
例如:

# docker top centos_name_1
UID PID PPID C STIME TTY TIME CMD
root 4468 4452 0 09:16 pts/2 00:00:00 /bin/bash
#

查看docker容器的负载

# docker stats centos_name_1

CONTAINER CPU % MEM USAGE / LIMIT MEM % NET I/O BLOCK I/O PIDS
centos_name_1 0.00% 392 KiB / 991 MiB 0.04% 22 MB / 600 kB 22.8 MB / 46 MB 1

docker自重启
在docker run 时，加入--restart=[always,on-failure:[number]]
--restart=always :docker 自动重启
--restart=on-failure :docker 只有在退出码非0的时候才会重启
--restart=on-failure:3 在退出码状态为非0的时候，重启，最多重启3次

例子 --restart=always :

# docker run -d --restart=always  nginx

创建一个docker 容器，现在来删除它

# ps aux | grep `docker ps | grep nginx | awk '{print $1}'` | grep -v grep | awk '{print $2}'
7583
# kill -9 7583
# ps aux | grep `docker ps | grep nginx | awk '{print $1}'` | grep -v grep | awk '{print $2}'
7842
# docker ps 
ONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                NAMES
d1ed69cb3238        nginx               "nginx -g 'daemon ..."   8 minutes ago       Up 47 seconds       0.0.0.0:80->80/tcp   affectionate_wiles
# 

我们可以发现，kill后进程又起来了

例子 --restart=--restart=on-failure:

# docker run -d --restart=on-failure:2 nginx 
6fabc743a488a857909ac4f1472a7f1012e2224e300da70aa15c1cb8f5db0767
# docker ps 
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS               NAMES
6fabc743a488        nginx               "nginx -g 'daemon ..."   2 seconds ago       Up 2 seconds        80/tcp              cocky_heisenberg
# 

#  ps aux | grep `docker ps | grep nginx | awk '{print $1}'` | grep -v grep | awk '{print $2}'
8030
# kill -9 8030
#  ps aux | grep `docker ps | grep nginx | awk '{print $1}'` | grep -v grep | awk '{print $2}'
8145
# kill -9 8145
#  ps aux | grep `docker ps | grep nginx | awk '{print $1}'` | grep -v grep | awk '{print $2}'
8242
# kill -9 8242
#  ps aux | grep `docker ps | grep nginx | awk '{print $1}'` | grep -v grep | awk '{print $2}'
Usage: grep [OPTION]... PATTERN [FILE]...
Try 'grep --help' for more information.
# 

发现，在重启两次后，该容器不重启了。

其实基础真的很重要~~~