podman简介
Podman 原来是 CRI-O 项目的一部分，后来被分离成一个单独的项目叫 libpod。Podman 的使用体验和 Docker 类似，不同的是 Podman 没有 daemon。以前使用 Docker CLI 的时候，Docker CLI 会通过 gRPC API 去跟 Docker Engine 说「我要启动一个容器」，然后 Docker Engine 才会通过 OCI Container runtime（默认是 runc）来启动一个容器。这就意味着容器的进程不可能是 Docker CLI 的子进程，而是 Docker Engine 的子进程。
Podman 比较简单粗暴，它不使用 Daemon，而是直接通过 OCI runtime（默认也是 runc）来启动容器，所以容器的进程是 podman 的子进程。这比较像 Linux 的 fork/exec 模型，而 Docker 采用的是 C/S（客户端/服务器）模型。与 C/S 模型相比，fork/exec 模型有很多优势，比如：
- 系统管理员可以知道某个容器进程到底是谁启动的。
- 如果利用 cgroup 对 podman 做一些限制，那么所有创建的容器都会被限制。
- SD_NOTIFY : 如果将 podman 命令放入 systemd 单元文件中，容器进程可以通过 podman
返回通知，表明服务已准备好接收任务。 - socket 激活 : 可以将连接的 socket 从 systemd 传递到 podman，并传递到容器进程以便使用它们。
Podman 兼容 Docker吗？
大部分是兼容的，例如：
1.可以直接使用 Docker 镜像
2.命令非常相似
如果你非常怀念 docker命令，甚至可以给 Podman 设置别名为 docker：
echo "alias docker=podman" >> .bashrc
source .bashrc
可以说podman大部分的命令与docker几乎一样
安装podman
yum -y install pod man
查看版本号
[root@ok ~]# podman -v
podman version 1.6.4
podman默认网段
“10.88.0.1/16”
10: cni-podman0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 1a:76:c4:35:8d:39 brd ff:ff:ff:ff:ff:ff
inet 10.88.0.1/16 brd 10.88.255.255 scope global cni-podman0
valid_lft forever preferred_lft forever
命令详解
[root@ok ~]# podman --help
manage pods and images
Usage:
podman [flags]
podman [command]
Available Commands:
attach Attach to a running container
build Build an image using instructions from Containerfiles
commit Create new image based on the changed container
container Manage Containers
cp Copy files/folders between a container and the local filesystem
create Create but do not start a container
diff Inspect changes on container's file systems
events Show podman events
exec Run a process in a running container
export Export container's filesystem contents as a tar archive
generate Generated structured data
healthcheck Manage Healthcheck
help Help about any command
history Show history of a specified image
image Manage images
images List images in local storage
import Import a tarball to create a filesystem image
info Display podman system information
init Initialize one or more containers
inspect Display the configuration of a container or image
kill Kill one or more running containers with a specific signal
load Load an image from container archive
login Login to a container registry
logout Logout of a container registry
logs Fetch the logs of a container
mount Mount a working container's root filesystem
network Manage Networks
pause Pause all the processes in one or more containers
play Play a pod
pod Manage pods
port List port mappings or a specific mapping for the container
ps List containers
pull Pull an image from a registry
push Push an image to a specified destination
restart Restart one or more containers
rm Remove one or more containers
rmi Removes one or more images from local storage
run Run a command in a new container
save Save image to an archive
search Search registry for image
start Start one or more containers
stats Display a live stream of container resource usage statistics
stop Stop one or more containers
system Manage podman
tag Add an additional name to a local image
top Display the running processes of a container
umount Unmounts working container's root filesystem
unpause Unpause the processes in one or more containers
unshare Run a command in a modified user namespace
varlink Run varlink interface
version Display the Podman Version Information
volume Manage volumes
wait Block on one or more containers
Flags:
--cgroup-manager string Cgroup manager to use (cgroupfs or systemd) (default "systemd")
--cni-config-dir string Path of the configuration directory for CNI networks
--config string Path of a libpod config file detailing container server configuration options
--conmon string Path of the conmon binary
--cpu-profile string Path for the cpu profiling results
--events-backend string Events backend to use
--help Help for podman
--hooks-dir strings Set the OCI hooks directory path (may be set multiple times)
--log-level string Log messages above specified level: debug, info, warn, error, fatal or panic (default "error")
--namespace string Set the libpod namespace, used to create separate views of the containers and pods on the system
--network-cmd-path string Path to the command for configuring the network
--root string Path to the root directory in which data, including images, is stored
--runroot string Path to the 'run directory' where all state information is stored
--runtime string Path to the OCI-compatible binary used to run containers, default is /usr/bin/runc
--storage-driver string Select which storage driver is used to manage storage of images and containers (default is overlay)
--storage-opt stringArray Used to pass an option to the storage driver
--syslog Output logging information to syslog as well as the console
--tmpdir string Path to the tmp directory
--trace Enable opentracing output
-v, --version Version of podman
Use "podman [command] --help" for more information about a command.
podman使用阿里云镜像加速
国内直接用 podman pull 拉取镜像会很慢，所以需要配置阿里云容器镜像来加速访问
Podman 默认注册表配置文件在 /etc/containers/registries.conf
清空并修改为以下内容：
unqualified-search-registries = ["docker.io"]
[[registry]]
prefix = "docker.io"
location = "******.mirror.aliyuncs.com"
把 location 对应的值修改为你的阿里云容器加速镜像地址就可以了，现在拉取镜像就是用的阿里云加速
pull镜像并运行
下载镜像
podman pull nginx
查看镜像
[root@ok system]# podman images
REPOSITORY TAG IMAGE ID CREATED SIZE
docker.io/library/nginx latest f6d0b4767a6c 2 months ago 137 MB
运行容器
[root@ok system]# podman run -itd --name nginx -p 9999:80 f6d0b4767a6c
15122785bee25e2987bbc0dff7060ff5b36e7f6cf994a72ef3a3ab3827ffa4b9
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