容器和虚拟机 Container vs VM

docker-vs-vm

容器不是Mini虚拟机

容器其实是进程Containers are just processes
容器中的进程被限制了对CPU内存等资源的访问
当进程停止后，容器就退出了

容器的进程process

显示容器的进程：docker container top <container ID>
image.png

Note
以下是在Ubuntu20.04中演示，因Windows环境下的Docker和Linux具有一些差异。pstree 命令需要额外安装，可以使用 yum install psmisc 或者 sudo apt-get install psmisc 安装

➜  ~ docker container run -d nginx
57fe4033dd7e1e620a0b6a7b83b85d4f8f98772f0ce585624c384de254826fd0
➜  ~ docker container ls
CONTAINER ID   IMAGE     COMMAND                  CREATED         STATUS         PORTS     NAMES
57fe4033dd7e   nginx     "/docker-entrypoint.…"   4 seconds ago   Up 3 seconds   80/tcp    festive_proskuriakova
➜  ~ docker container top 57f
UID                 PID                 PPID                C                   STIME               TTY                 TIME                CMD
root                7646                7625                0                   12:14               ?                   00:00:00            nginx: master process nginx -g daemon off;
systemd+            7718                7646                0                   12:14               ?                   00:00:00            nginx: worker process
➜  ~
➜  ~
➜  ~  ps -aef --forest
UID        PID  PPID  C STIME TTY          TIME CMD
root         1     0  0 May14 ?        00:00:00 /init
root       157     1  0 May14 ?        00:00:00 /init
root       523   157  0 May14 ?        00:02:32  \_ /usr/bin/dockerd -p /var/run/docker.pid
root       545   523  0 May14 ?        00:25:55  |   \_ containerd --config /var/run/docker/containerd/containerd.toml --log-level info
root      7625   157  0 12:14 ?        00:00:00  \_ /usr/bin/containerd-shim-runc-v2 -namespace moby -id 57fe4033dd7e1e620a0b6a7b83b85d4f8f98772f0ce585624c384de254826fd0 -address /var/run/d
root      7646  7625  0 12:14 ?        00:00:00      \_ nginx: master process nginx -g daemon off;
systemd+  7718  7646  0 12:14 ?        00:00:00          \_ nginx: worker process
root      6442     1  0 May18 ?        00:00:00 /init
root      6443  6442  0 May18 ?        00:00:00  \_ /init
penxiao   6444  6443  0 May18 pts/2    00:00:01      \_ -zsh
penxiao   7770  6444  0 12:15 pts/2    00:00:00          \_ ps -aef --forest
➜  ~
➜  ~ pstree -halps 7718
init,1
└─init,157
    └─containerd-shim,7625 -namespace moby -id 57fe4033dd7e1e620a0b6a7b83b85d4f8f98772f0ce585624c384de254826fd0 -address /var/run/docker/containerd/containerd.sock
        └─nginx,7646
            └─nginx,7718