我想设置自定义目录来存储使用Podman创建的容器数据，如何将目录文件类型(及其内容)更改为Podman使用的上下文类型？在运行SELinux的系统上，所有进程和文件都以表示安全相关信息的方式标记。如果我们尝试使用存储在/var/lib/containers以外的目录中的数据创建一个容器，则会获得权限被拒绝。

我将在CentOS 8服务器上对此进行演示。让SELinux进入Enforcecing模式。

$sudo setenforce 1
$sestatus
SELinux status:                 enabled
SELinuxfs mount:                /sys/fs/selinux
SELinux root directory:         /etc/selinux
Loaded policy name:             targeted
Current mode:                   enforcing
Mode from config file:          enforcing
Policy MLS status:              enabled
Policy deny_unknown status:     allowed
Memory protection checking:     actual (secure)
Max kernel policy version:      31

安装提供podman的Container工具。

sudo dnf module install container-tools

让我们通过运行helloworld容器来确认podman是否按预期工作。

$podman run --rm hello-world

Trying to pull docker.io/library/hello-world...
Getting image source signatures
Copying blob 0e03bdcc26d7 done
Copying config bf756fb1ae done
Writing manifest to image destination
Storing signatures

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/

确认容器的当前根目录设置。

$podman info | grep -i root
  rootless: false
  GraphRoot: /var/lib/containers/storage
  RunRoot: /var/run/containers/storage

让我们创建用于存储数据的自定义目录。

sudo mkdir -p /data/containers

更新设置并将目录更改为上面创建的目录。

$sudo vi /etc/containers/storage.conf
# Primary Read/Write location of container storage
#graphroot = "/var/lib/containers/storage"
graphroot = "/data/containers"

尝试运行一个容器。

# podman run --rm -it  ubuntu bash
Getting image source signatures
Copying blob 0f3630e5ff08 done
Copying blob d72e567cc804 done
Copying blob b6a83d81d1f4 done
Copying config 9140108b62 done
Writing manifest to image destination
Storing signatures
bash: error while loading shared libraries: libc.so.6: cannot change memory protections

从输出中我得到了错误消息：

bash: error while loading shared libraries: libc.so.6: cannot change memory protections

让我们为目录/data/containers设置正确的SELinux标签，然后重试。

sudo semanage fcontext -a -e /var/lib/containers /data/containers
sudo restorecon -R -vv /data/containers

如果找不到semanage命令，请使用以下命令进行安装。

sudo yum install policycoreutils-python-utils -y

确认SELinux上下文类型。

$ls -dZ /data/containers/
unconfined_u:object_r:container_var_lib_t:s0 /data/containers/

确认类型是否已设置为container_var_lib_t。

重新运行容器：

# podman run --rm -it  ubuntu bash
theitroad@localhost:/# cat /etc/os-release
NAME="Ubuntu"
VERSION="20.04.1 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04.1 LTS"
VERSION_ID="20.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal
theitroad@localhost:/# exit
exit

容器已成功启动。