Docker属于对Linux容器技术（LXC）的一种封装（利用了Linux的namespace和cgroup技术），它提供了简单易用的容器使用接口，是目前最流行的 Linux 容器解决方案。Docker将应用程序与该程序的依赖打包在一个文件里面，运行这个文件，就会生成一个虚拟容器。程序在这个虚拟容器里运行，就好像在真实的物理机上运行一样。下图是虚拟机和容器的对比，左边是传统的虚拟机，右边是Docker。
Hello from Docker!
This message shows that your installation appears to be working correctly.
To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
(amd64)
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.
To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash
Share images, automate workflows, and more with a free Docker ID:
https://hub.docker.com/
For more examples and ideas, visit:
https://docs.docker.com/get-started/
mysql -u root -p
Enter password:
Your MySQL connection id is 16
Server version: 8.0.12 MySQL Community Server - GPL
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>
接下来通过SQL来修改用户口令就可以了。
alter user 'root'@'%' identified with mysql_native_password by '123456' password expire never;
当然，如果愿意你也可以查看一下用户表检查是否修改成功。
use mysql;
select user, host, plugin, authentication_string from user where user='root';
+------+-----------+-----------------------+-------------------------------------------+
| user | host | plugin | authentication_string |
+------+-----------+-----------------------+-------------------------------------------+
| root | % | mysql_native_password | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 |
| root | localhost | mysql_native_password | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 |
+------+-----------+-----------------------+-------------------------------------------+
2 rows in set (0.00 sec)
REPOSITORY TAG IMAGE ID CREATED SIZE
jackfrued/myapp latest 6d6f026a7896 5 seconds ago 930 MB
如果想知道镜像文件是如何创建出来的，可以使用下面的命令。
docker history jackfrued/myapp
IMAGE CREATED CREATED BY SIZE COMMENT
6d6f026a7896 31 seconds ago /bin/sh -c #(nop) EXPOSE 8000/tcp 0 B
3f7739173a79 31 seconds ago /bin/sh -c #(nop) ENTRYPOINT ["./start.sh"] 0 B
321e6bf09bf1 32 seconds ago /bin/sh -c pip install -r requirements.txt... 13 MB
2f9bf2c89ac7 37 seconds ago /bin/sh -c #(nop) WORKDIR /root/api 0 B
86119afbe1f8 37 seconds ago /bin/sh -c #(nop) ADD multi:4b76f9c9dfaee8... 870 B
08d465e90d4d 3 hours ago /bin/sh -c #(nop) MAINTAINER jackfrued "j... 0 B
fbf9f709ca9f 12 days ago /bin/sh -c #(nop) CMD ["python3"] 0 B
使用该镜像来创建容器运行Web服务器。
docker run -d -p 8000:8000 --name myapp jackfrued/myapp
如果希望将上面创建的镜像文件放到dockerhub仓库中，可以按照如下所示的步骤进行操作。
通过下面的命令登录到dockerhub。
docker login
输入用户名和口令进行登录。
Login with your Docker ID to push and pull images from Docker Hub. If you don't have a Docker ID, head over to https://hub.docker.com to create one.
Username: jackfrued
Password:
Login Succeeded
[ECS-root temp]# docker-compose up
Creating network "temp_default" with the default driver
Creating temp_web-server_1 ... done
Creating temp_redis-master_1 ... done
Creating temp_api-server_1 ... done
Attaching to temp_redis-master_1, temp_web-server_1, temp_api-server_1
redis-master_1 | 1:C 05 Dec 2019 11:57:26.828 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
redis-master_1 | 1:C 05 Dec 2019 11:57:26.828 # Redis version=5.0.6, bits=64, commit=00000000, modified=0, pid=1, just started
redis-master_1 | 1:C 05 Dec 2019 11:57:26.828 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
redis-master_1 | 1:M 05 Dec 2019 11:57:26.830 * Running mode=standalone, port=6379.
redis-master_1 | 1:M 05 Dec 2019 11:57:26.831 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
redis-master_1 | 1:M 05 Dec 2019 11:57:26.831 # Server initialized
redis-master_1 | 1:M 05 Dec 2019 11:57:26.831 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
redis-master_1 | 1:M 05 Dec 2019 11:57:26.831 # WARNING you have Transparent Huge Pages (THP) support enabled in your kernel. This will create latency and memory usage issues with Redis. To fix this issue run the command 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' as root, and add it to your /etc/rc.local in order to retain the setting after a reboot. Redis must be restarted after THP is disabled.
redis-master_1 | 1:M 05 Dec 2019 11:57:26.831 * Ready to accept connections
api-server_1 | [2019-12-05 11:57:27 +0000] [1] [INFO] Starting gunicorn 20.0.4
api-server_1 | [2019-12-05 11:57:27 +0000] [1] [INFO] Listening at: http://0.0.0.0:8000 (1)
api-server_1 | [2019-12-05 11:57:27 +0000] [1] [INFO] Using worker: sync
api-server_1 | [2019-12-05 11:57:27 +0000] [8] [INFO] Booting worker with pid: 8
api-server_1 | [2019-12-05 11:57:27 +0000] [9] [INFO] Booting worker with pid: 9
api-server_1 | [2019-12-05 11:57:27 +0000] [10] [INFO] Booting worker with pid: 10
api-server_1 | [2019-12-05 11:57:27 +0000] [11] [INFO] Booting worker with pid: 11
