Container 是一种轻量级的虚拟化技术，不用模拟硬件创建虚拟机。
Docker 是基于 Linux Kernel 的 Namespace、CGroups、UnionFileSystem 等技术封装成的一种自 定义容器格式，从而提供一套虚拟运行环境。
Namespace：用来做隔离的，比如 pid [进程]、net [网络]、mnt [挂载点]等。
CGroups: Controller Groups用来做资源限制，比如内存和CPU等。
Union file systems：用来做image和container分层。
安装依赖
sudo yum install -y yum-utils \ device-mapper-persistent-data \ lvm2（以下可以使用阿里云镜像速度快，参考地址：https://blog.csdn.net/DavidSoCool/article/details/102915527）
设置docker仓库
sudo yum-config-manager \ --add-repo \ https://download.docker.com/linux/centos/docker-ce.repo安装docker
sudo yum install -y docker-ce docker-ce-cli containerd.io设置开机启动
sudo systemctl enable docker启动docker
sudo systemctl start docker查看版本
运行hello-world镜像生成容器，会先从本地查找，找不到去远端拉取在运行（镜像和容器的关系就像java里面的class文件和创建出来的对象）
拉取tomcat镜像，不指定版本默认拉取最新的，指定版本可以去hub.docker.com上面找，镜像名字不对会报错
查看本地镜像
运行镜像， -d 后台运行，--name 别名，-p 对外端口 9090 对内 8080，运行对应的一些环境变量参数可以去hub.docker.com看
docker run -d --name my-tomcat -p 9090:8080 tomcat查看后台运行container
在多创建几个tomcat的container
查看运行的container
查看所有包括退出的container
docker命令
Usage: docker [OPTIONS] COMMAND A self-sufficient runtime for containers Options: --config string Location of client config files (default "/root/.docker") -c, --context string Name of the context to use to connect to the daemon (overrides DOCKER_HOST env var and default context set with "docker context use") -D, --debug Enable debug mode -H, --host list Daemon socket(s) to connect to -l, --log-level string Set the logging level ("debug"|"info"|"warn"|"error"|"fatal") (default "info") --tls Use TLS; implied by --tlsverify --tlscacert string Trust certs signed only by this CA (default "/root/.docker/ca.pem") --tlscert string Path to TLS certificate file (default "/root/.docker/cert.pem") --tlskey string Path to TLS key file (default "/root/.docker/key.pem") --tlsverify Use TLS and verify the remote -v, --version Print version information and quit Management Commands: builder Manage builds config Manage Docker configs container Manage containers context Manage contexts engine Manage the docker engine image Manage images network Manage networks node Manage Swarm nodes plugin Manage plugins secret Manage Docker secrets service Manage services stack Manage Docker stacks swarm Manage Swarm system Manage Docker trust Manage trust on Docker images volume Manage volumes Commands: attach Attach local standard input, output, and error streams to a running container build Build an image from a Dockerfile commit Create a new image from a container's changes cp Copy files/folders between a container and the local filesystem create Create a new container diff Inspect changes to files or directories on a container's filesystem events Get real time events from the server exec Run a command in a running container export Export a container's filesystem as a tar archive history Show the history of an image images List images import Import the contents from a tarball to create a filesystem image info Display system-wide information inspect Return low-level information on Docker objects kill Kill one or more running containers load Load an image from a tar archive or STDIN login Log in to a Docker registry logout Log out from a Docker registry logs Fetch the logs of a container pause Pause all processes within one or more containers port List port mappings or a specific mapping for the container ps List containers pull Pull an image or a repository from a registry push Push an image or a repository to a registry rename Rename a container restart Restart one or more containers rm Remove one or more containers rmi Remove one or more images run Run a command in a new container save Save one or more images to a tar archive (streamed to STDOUT by default) search Search the Docker Hub for images start Start one or more stopped containers stats Display a live stream of container(s) resource usage statistics stop Stop one or more running containers tag Create a tag TARGET_IMAGE that refers to SOURCE_IMAGE top Display the running processes of a container unpause Unpause all processes within one or more containers update Update configuration of one or more containers version Show the Docker version information wait Block until one or more containers stop, then print their exit codes Run 'docker COMMAND --help' for more information on a command.
