1.创建容器时没有添加参数 --restart=always ，导致的后果是：当 Docker 重启时，容器未能自动启动。

docker container update --restart=always 容器名字

操作实例如下：
[root@localhost mnt]# docker ps -a
CONTAINER ID        IMAGE               COMMAND                  CREATED              STATUS              PORTS               NAMES
46cdfc60b7a6        nginx               "nginx -g 'daemon ..."   About a minute ago   Up 42 seconds       80/tcp              n3
79d55a734c26        nginx               "nginx -g 'daemon ..."   About a minute ago   Up 42 seconds       80/tcp              n2
f7b2206c019d        nginx               "nginx -g 'daemon ..."   About a minute ago   Up 46 seconds       80/tcp              n1
[root@localhost mnt]# docker container update --restart=always n1
n1
[root@localhost mnt]# systemctl restart docker 
[root@localhost mnt]# docker ps -a
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                     PORTS               NAMES
46cdfc60b7a6        nginx               "nginx -g 'daemon ..."   2 minutes ago       Exited (0) 5 seconds ago                       n3
79d55a734c26        nginx               "nginx -g 'daemon ..."   2 minutes ago       Exited (0) 5 seconds ago                       n2
f7b2206c019d        nginx               "nginx -g 'daemon ..."   2 minutes ago       Up 2 seconds               80/tcp              n1

2.docker-compose 关机或者重启docker同时重启容器restart always的配置

众所周知，存粹使用docker启动的话需要加–restart=always即可实现这个功能，而使用docker-compose的话在相关服务配置下加 restart: always 就行

version: '2'
services:
  database:
    build: ./mysql/
    command: mysqld --user=root --verbose
    restart: always 
    environment:
      MYSQL_DATABASE: "web_level3_sqli"
      MYSQL_USER: "web_level3_sqli"
      MYSQL_PASSWORD: "thisisasecurepassword123"
      MYSQL_ROOT_PASSWORD: "root"
      MYSQL_ALLOW_EMPTY_PASSWORD: "yes"
  web:
    build: ./www/
    restart: always
    ports:
     - "12000:80"
    volumes:
      - ./www/src:/var/www/html
    links:
      - database