はじめに
RHEL8ではDockerコンテナーエンジンとDockerコマンドが削除されたと知り、代替となるPodmanコマンドでコンテナーを構築した備忘録。
動作環境
- Rocky Linux release 8.5 (Green Obsidian)
Dockerに変わるツール
- Podman：コンテナーの実行と管理担当
- Skopeo：コンテナーイメージのコピーと検証担当
- Buildad：コンテナーイメージ構築担当
インストール手順
コンテナーツールの取得手順。
1. 管理者権限でコンテナーツールをインストール
$ sudo yum module install -y container-tools
2. インストール確認
$ yum list installed | grep podman
cockpit-podman.noarch 39-1.module+el8.5.0+735+2f243138 @appstream
podman.x86_64 1:3.4.2-9.module+el8.5.0+735+2f243138 @appstream
podman-catatonit.x86_64 1:3.4.2-9.module+el8.5.0+735+2f243138 @appstream
python3-podman.noarch 3.2.1-1.module+el8.5.0+735+2f243138 @appstream
3. helpの確認
$ podman help
Manage pods, containers and images
Usage:
podman [options] [command]
Available Commands:
attach Attach to a running container
auto-update Auto update containers according to their auto-update policy
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 Display the changes to the object's file system
events Show podman events
exec Run a process in a running container
export Export container's filesystem contents as a tar archive
generate Generate structured data based on containers, pods or volumes
healthcheck Manage health checks on containers
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 object denoted by ID
kill Kill one or more running containers with a specific signal
load Load image(s) from a tar archive
login Login to a container registry
logout Logout of a container registry
logs Fetch logs for pod with one or more containers
logs Fetch the logs of one or more containers
machine Manage a virtual machine
manifest Manipulate manifest lists and image indexes
mount Mount a working container's root filesystem
network Manage networks
pause Pause all the processes in one or more containers
play Play containers, pods or volumes from a structured file
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
rename Rename an existing container
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(s) to an archive
search Search registry for image
secret Manage secrets
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
unmount Unmounts working container's root filesystem
unpause Unpause the processes in one or more containers
unshare Run a command in a modified user namespace
untag Remove a name from a local image
version Display the Podman version information
volume Manage volumes
wait Block on one or more containers
Options:
--cgroup-manager string Cgroup manager to use ("cgroupfs"|"systemd") (default "cgroupfs")
--cni-config-dir string Path of the configuration directory for CNI networks
--conmon string Path of the conmon binary
-c, --connection string Connection to use for remote Podman service
--events-backend string Events backend to use ("file"|"journald"|"none") (default "file")
--help Help for podman
--hooks-dir strings Set the OCI hooks directory path (may be set multiple times) (default [/usr/share/containers/oci/hooks.d])
--identity string path to SSH identity file, (CONTAINER_SSHKEY)
--log-level string Log messages above specified level (trace, debug, info, warn, warning, error, fatal, panic) (default "warn")
--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
-r, --remote Access remote Podman service (default false)
--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
--runtime-flag stringArray add global flags for the container runtime
--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 (default false)
--tmpdir string Path to the tmp directory for libpod state content.
Note: use the environment variable 'TMPDIR' to change the temporary storage location for container images, '/var/tmp'.
--url string URL to access Podman service (CONTAINER_HOST) (default "unix:/run/user/1000/podman/podman.sock")
4. versionの確認
$ podman version
Version: 3.4.2
API Version: 3.4.2
Go Version: go1.16.12
Built: Wed Feb 2 08:59:28 2022
OS/Arch: linux/amd64
5. hello-worldコンテナーの起動
$ podman run --rm hello-world
Resolved "hello-world" as an alias (/etc/containers/registries.conf.d/000-shortnames.conf)
Trying to pull docker.io/library/hello-world:latest...
Getting image source signatures
Copying blob 2db29710123e done
Copying config feb5d9fea6 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/