1.容器 vs 虚拟机

共同点:
1.容器和虚拟机都需要依赖宿主机才能运行

不同点:
对于系统资源的处理方式
虚拟机:
是硬件虚拟化，将因减肥物理资源划分为虚拟资源。

容器：
是将系统资源划分为虚拟资源。
os也占领了全部硬件资源。在os层之上, 需要安装容器引擎(如docker)。容器引擎可以获取系统资源，比如进程树，文件系统以及网络栈，接着将资源分割为安全的互相隔离的资源结构，称之为容器。

占用系统资源
虚拟机中每个操作系统都会占用一点系统资源。
容器共享一个操作系统/内核。这意味着只有一个操作系统消耗CPU， RAM 和存储资源，只有一份OS损耗。

启动时间
虚拟机启动要重启内核开始
容器需要的是位于下层操作系统的共享内核是启动了的。唯一对容器启动时间有影响的是容器内应用启动所花费的时间。8

2.检查 docker daemon

  1. # 1. 检查docker是否正在运行
  2. [vic@izwz93lmtccp8mvky0xj4uz ~]$ docker version
  3. Client: Docker Engine - Community
  4.  Version:           19.03.12
  5.  API version:       1.40
  6.  Go version:        go1.13.10
  7.  Git commit:        48a66213fe
  8.  Built:             Mon Jun 22 15:46:54 2020
  9.  OS/Arch:           linux/amd64
  10.  Experimental:      false
  12. Server: Docker Engine - Community
  13.  Engine:
  14.   Version:          19.03.12
  15.   API version:      1.40 (minimum version 1.12)
  16.   Go version:       go1.13.10
  17.   Git commit:       48a66213fe
  18.   Built:            Mon Jun 22 15:45:28 2020
  19.   OS/Arch:          linux/amd64
  20.   Experimental:     false
  21.  containerd:
  22.   Version:          1.2.13
  23.   GitCommit:        7ad184331fa3e55e52b890ea95e65ba581ae3429
  24.  runc:
  25.   Version:          1.0.0-rc10
  26.   GitCommit:        dc9208a3303feef5b3839f4323d9beb36df0a9dd
  27.  docker-init:
  28.   Version:          0.18.0
  29.   GitCommit:        fec3683
  31. # 2.检查 docker status 状态
  32. [vic@izwz93lmtccp8mvky0xj4uz ~]$ service docker status
  33. Redirecting to /bin/systemctl status  docker.service
  34. ● docker.service - Docker Application Container Engine
  35.    Loaded: loaded (/usr/lib/systemd/system/docker.service; disabled; vendor preset: disabled)
  36.    Active: active (running) since Mon 2020-07-27 16:19:11 CST; 18h ago
  37.      Docs: https://docs.docker.com
  38.  Main PID: 4591 (dockerd)
  39.    Memory: 132.0M
  40.    CGroup: /system.slice/docker.service
  41.            └─4591 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock
  43. # 3.检查 docker 是否是有效的
  44. [vic@izwz93lmtccp8mvky0xj4uz ~]$ systemctl is-active docker
  45. active

3.运行容器

  1. docker contain run <options> <image>:<tag> <app>
  3. optins 命令参数
  4. -it 使容器具备交互性并与终端进行连接

4.容器进程

ps -elf

通过 ps -elf 命令在容器内部查看

  1. root@ba35c3926bfe:/# ps -elf
  2. F S UID        PID  PPID  C PRI  NI ADDR SZ WCHAN  STIME TTY          TIME CMD
  3. 4 S root         1     0  0  80   0 -  1025 do_wai 05:48 pts/0    00:00:00 /bin/bash
  4. 0 R root        10     1  0  80   0 -  1468 -      05:48 pts/0    00:00:00 ps -elf

如果通过 exit 退出 Bash Shell, 那么容器也会退出(终止)。 原因是容器如果不运行任何进程则无法存在。
杀死容器的主进程, 则容器也会被杀死。

容器后台运行

按下 Ctrl-PQ 组合键则会退出容器但并不终止容器运行。

查看当前系统正在运行的容器列表,
docker container ls

  1. [vic@izwz93lmtccp8mvky0xj4uz ~]$ docker container ls
  2. CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
  3. ba35c3926bfe        ubuntu:latest       "/bin/bash"         4 minutes ago       Up 4 minutes                            modest_kepler

终端重连到 Docker

当前容器仍然在运行, 并且可以通过 docker container exec 命令将终端重新连接到 Docker。

  1. $ docker container exec -it ba35c3926bfe bash

5.停止并删除容器

  1. # 1.停止
  2. $ docker container stop ba35c3926bfe
  4. # 2.删除
  5. $ docker container rm ba35c3926bfe

6.容器生命周期

容器的生命周期：从创建、运行、休眠、直至销毁的整个过程。
停止容器并不会损毁容器或者其中的数据。
卷(volume)才是容器中存储持久化数据的首选方式。

删除容器的最佳方式是两步: 先停止容器然后删除。

7.重启策略进行容器的自我修复

三种重启策略
always: 当 Docker daemon 重启时, 当 daemon 启动完成时, 该容器也会重新启动。
unless-stopped: 当处于 stopped(Exited) 状态的容器， 不会在 Docker daemon 重启的时候被重启
on-failed: 在退出容器并且返回值不是0的时候，重启容器。当处于 stopped 状态，在Docker daemon 重启的是时候，容器也会被重启。

  1. [vic@izwz93lmtccp8mvky0xj4uz ~]$ docker container ls
  2. CONTAINER ID        IMAGE               COMMAND             CREATED              STATUS              PORTS               NAMES
  3. a94ee5c7e815        alpine              "sleep 1d"          4 seconds ago        Up 4 seconds                            on-failure
  4. d3474f264212        alpine              "sleep 1d"          41 seconds ago       Up 40 seconds                           unless-stopped
  5. 6bbe398c3ec1        alpine              "sleep 1d"          About a minute ago   Up About a minute                       always
  6. 6dc1cf0d9695        ubuntu:latest       "/bin/bash"         33 minutes ago       Up 31 minutes                           percy
  8. [vic@izwz93lmtccp8mvky0xj4uz ~]$ docker container stop a94ee5c7e815
  9. a94ee5c7e815
  10. [vic@izwz93lmtccp8mvky0xj4uz ~]$ docker container ls
  11. CONTAINER ID        IMAGE               COMMAND             CREATED              STATUS              PORTS               NAMES
  12. d3474f264212        alpine              "sleep 1d"          About a minute ago   Up About a minute                       unless-stopped
  13. 6bbe398c3ec1        alpine              "sleep 1d"          2 minutes ago        Up 2 minutes                            always
  15. [vic@izwz93lmtccp8mvky0xj4uz ~]$ docker container stop unless-stopped
  16. unless-stopped
  17. [vic@izwz93lmtccp8mvky0xj4uz ~]$ docker container ls
  18. CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
  19. 6bbe398c3ec1        alpine              "sleep 1d"          3 minutes ago       Up 3 minutes                            always
  20. 6dc1cf0d9695        ubuntu:latest       "/bin/bash"         35 minutes ago      Up 32 minutes                           percy
  21. [vic@izwz93lmtccp8mvky0xj4uz ~]$ docker container stop always
  22. always
  23. [vic@izwz93lmtccp8mvky0xj4uz ~]$ docker container ls
  24. CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
  25. 6dc1cf0d9695        ubuntu:latest       "/bin/bash"         35 minutes ago      Up 32 minutes                           percy
  26. [vic@izwz93lmtccp8mvky0xj4uz ~]$ docker container ls -a
  27. CONTAINER ID        IMAGE               COMMAND             CREATED              STATUS                            PORTS               NAMES
  28. a94ee5c7e815        alpine              "sleep 1d"          About a minute ago   Exited (137) About a minute ago                       on-failure
  29. d3474f264212        alpine              "sleep 1d"          2 minutes ago        Exited (137) 27 seconds ago                           unless-stopped
  30. 6bbe398c3ec1        alpine              "sleep 1d"          3 minutes ago        Exited (137) 4 seconds ago                            always
  31. fa4a0c4cb71a        alpine              "sh"                21 minutes ago       Exited (137) 19 minutes ago                           neversaydie
  32. 6dc1cf0d9695        ubuntu:latest       "/bin/bash"         35 minutes ago       Up 32 minutes                                         percy
  33. [vic@izwz93lmtccp8mvky0xj4uz ~]$ systemctl restart docker
  34. ==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
  35. Authentication is required to manage system services or units.
  36. Authenticating as: root
  37. Password: 
  38. ==== AUTHENTICATION COMPLETE ===
  39. [vic@izwz93lmtccp8mvky0xj4uz ~]$ docker container ls -a
  40. CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                        PORTS               NAMES
  41. a94ee5c7e815        alpine              "sleep 1d"          2 minutes ago       Up 5 seconds                                      on-failure
  42. d3474f264212        alpine              "sleep 1d"          2 minutes ago       Exited (137) 51 seconds ago                       unless-stopped
  43. 6bbe398c3ec1        alpine              "sleep 1d"          3 minutes ago       Up 5 seconds                                      always
  44. fa4a0c4cb71a        alpine              "sh"                22 minutes ago      Up 5 seconds                                      neversaydie
  45. 6dc1cf0d9695        ubuntu:latest       "/bin/bash"         36 minutes ago      Exited (0) 7 seconds ago                          percy
  46. [vic@izwz93lmtccp8mvky0xj4uz ~]$ docker container start unless-stopped
  47. unless-stopped
  48. [vic@izwz93lmtccp8mvky0xj4uz ~]$ docker container ls -a
  49. CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                      PORTS               NAMES
  50. a94ee5c7e815        alpine              "sleep 1d"          2 minutes ago       Up 36 seconds                                   on-failure
  51. d3474f264212        alpine              "sleep 1d"          3 minutes ago       Up 5 seconds                                    unless-stopped
  52. 6bbe398c3ec1        alpine              "sleep 1d"          4 minutes ago       Up 36 seconds                                   always
  53. fa4a0c4cb71a        alpine              "sh"                22 minutes ago      Up 36 seconds                                   neversaydie
  54. 6dc1cf0d9695        ubuntu:latest       "/bin/bash"         36 minutes ago      Exited (0) 37 seconds ago                       percy
  55. [vic@izwz93lmtccp8mvky0xj4uz ~]$ systemctl restart docker
  56. ==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
  57. Authentication is required to manage system services or units.
  58. Authenticating as: root
  59. Password: 
  60. ==== AUTHENTICATION COMPLETE ===
  61. [vic@izwz93lmtccp8mvky0xj4uz ~]$ docker container ls -a
  62. CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                          PORTS               NAMES
  63. a94ee5c7e815        alpine              "sleep 1d"          3 minutes ago       Up 3 seconds                                        on-failure
  64. d3474f264212        alpine              "sleep 1d"          3 minutes ago       Up 3 seconds                                        unless-stopped
  65. 6bbe398c3ec1        alpine              "sleep 1d"          4 minutes ago       Up 3 seconds                                        always
  66. fa4a0c4cb71a        alpine              "sh"                23 minutes ago      Up 3 seconds                                        neversaydie
  67. 6dc1cf0d9695        ubuntu:latest       "/bin/bash"         37 minutes ago      Exited (0) About a minute ago                       percy

8.web服务示例

  1. # 运行示例
  2. # 参数
  3. # -d 表示后台模式, 告知容器在后台运行
  4. # -p 参数将 Docker 主机的端口映射到容器内。将 Docker 主机的 80 端口映射到了容器内的 8080 端口。
  5. # 当有流量访问主机 80 端口的时候, 流量会直接映射到容器内的8080端口。
  7. $ docker container run -d --name websever -p 80:8080 nigelpoulton/pluralsight-docker-ci
  8. Unable to find image 'nigelpoulton/pluralsight-docker-ci:latest' locally
  9. latest: Pulling from nigelpoulton/pluralsight-docker-ci
  10. 729ec3a6ada3: Pull complete 
  11. f0a3eea3dca0: Pull complete 
  12. e07851c50ad6: Pull complete 
  13. f78e7cd1f8dc: Pull complete 
  14. 7cad1fbd2f07: Pull complete 
  15. 22835c51693f: Pull complete 
  16. Digest: sha256:61bc64850a5f2bfbc65967cc33feaae8a77c8b49379c55aaf05bb02dcee41451
  17. Status: Downloaded newer image for nigelpoulton/pluralsight-docker-ci:latest
  18. f6a73b675b2aadf75af691aff9d2fd1049af2d38df33b27e8f5ea25bb52a417a