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Linux - Container: Package `podman`

Linux - Container: Package podman

Podman

Podman (short for Pod Manager)
- an open-source container management tool developed by Red Hat.
- It provides a daemonless alternative to Docker for building, running, and managing containers and pods.
- Podman uses the same container image format as Docker and is compatible with Open Container Initiative (OCI) standards.
images
- used to create containers
pod
- a group of containers, similar to Kubernetes pods, enabling better control over multi-container applications.
Features
- Daemonless Architecture:
  - Unlike Docker, Podman does not require a background daemon.
  - Containers are run as child processes of the Podman CLI.
  - This architecture makes Podman more secure and lightweight.
- Rootless Containers:
  - Podman supports running containers as a non-root user, enhancing security by reducing the risk of privilege escalation.
- OCI Compliance:
  - Podman adheres to the OCI standards for container images and runtimes, ensuring portability and compatibility with other tools like Kubernetes.
- Docker-Compatible Commands:
  - Many Docker commands work with Podman, making it easy for users to transition from Docker.
- Pods:
  - Podman allows managing groups of containers as pods, similar to Kubernetes pods, enabling better control over multi-container applications.
- Built-In Systemd Integration:
  - Podman can generate systemd service files to manage containers as system services.

Podman vs Docker

Feature	Podman	Docker
Architecture	Daemonless	Daemon-based
Rootless	Fully supports `rootless mode`	Limited support
Pods	Supports `pods` (native to Kubernetes)	No native pod support
Systemd Integration	Built-in systemd support	Requires manual setup
Security	More secure by default, no root daemon	Requires root daemon for full functionality
Compatibility	Supports Docker images and commands	Native support for Docker tools

Common Podman Commands

Common Commands

CMD	DESC
`podman -V`	Check Podman Version
`podman info`	Display Podman related system information

Registry Commands

Command	Description
`podman search img_pattern`	Search for an image in a remote registry.
`podman pull img_url`	Pull an image from a container registry (e.g., Docker Hub, Quay.io).
`podman push img_name`	Push an image to a remote registry.

Local Image Management Commands

Command	Description
`podman images`	List all available images locally.
`podman build -t tag_name .`	Build an image from a Dockerfile in the current directory.
`podman rm img_name`	Remove a local image.
`podman inspect img_name`	View detailed information about a local image.
`podman tag img_name tag_name`	Tag an image with a new name or tag.
`podman commit con_name image_name`	Create a new image from a container’s current state.

Container Management Commands

Command	Description
`podman ps`	List all running containers.
`podman ps -a`	List all containers, including stopped ones.
`podman run image_name`	Run a container from an image.
`podman run -d image_name`	Run a container in detached mode.
`podman run -it image_name`	Run a container interactively.
`podman run -d --name con_name -p host_port:con_port img_name`	Run a Container
`podman start con_name`	Start a stopped container.
`podman stop con_name`	Stop a running container.
`podman restart con_name`	Restart a container.
`podman rm con_name`	Remove a container.
`podman exec -it con_name bash`	Execute a command (e.g., a shell) inside a running container.
`podman logs con_name`	View logs for a container.
`podman stats con_name`	Show resource usage statistics for running containers.
`podman inspect con_name`	View detailed information about a container.
`podman cp con_name:con_path host_dest`	Copy files from a container to the host.
`podman generate systemd --name con_name`	Generate a systemd Service File

Pod Management Commands

Command	Description
`podman pod ps`	List all running pods.
`podman pod ps -a`	List all pods, including stopped ones.
`podman pod top pod_name`	Display active processes in a pod.
`podman pod create --name pod_name`	Create a new pod.
`podman pod rm pod_name`	Remove a pod (stops and removes all associated containers).
`podman run -dt --pod pod_name img_name`	Add a container to an existing pod and run it.
`podman pod start pod_name`	Start a stopped pod.
`podman pod stop pod_name`	Stop a running pod.
`podman pod restart pod_name`	Restart a pod.
`podman pod inspect pod_name`	View detailed information about a pod.
`podman pod logs pod_name`	View logs from all containers in a pod.
`podman generate kube pod_name`	Generate a Kubernetes YAML manifest for a pod.

Package and Service

Installing package

dnf install podman -y
rpm -qa | grep podman
# podman-gvproxy-4.9.4-18.module+el8.10.0+22417+2fb00970.x86_64
# podman-catatonit-4.9.4-18.module+el8.10.0+22417+2fb00970.x86_64
# podman-plugins-4.9.4-18.module+el8.10.0+22417+2fb00970.x86_64
# podman-4.9.4-18.module+el8.10.0+22417+2fb00970.x86_64

podman -v
# podman version 4.9.4-rhel

Service

To create Alias for docker using podman

alias docker=podman

Lab: Download Image

# Search an image
podman search docker.io/library/httpd
# NAME                              DESCRIPTION
# docker.io/library/httpd           The Apache HTTP Server Project
# docker.io/manageiq/httpd          Container with httpd, built on CentOS for Ma...
# docker.io/paketobuildpacks/httpd
# docker.io/vulhub/httpd
# docker.io/jitesoft/httpd          Apache httpd on Alpine linux.
# docker.io/openquantumsafe/httpd   Demo of post-quantum cryptography in Apache...
# docker.io/openeuler/httpd
# docker.io/dockerpinata/httpd
# docker.io/centos/httpd
# docker.io/e2eteam/httpd
# docker.io/manasip/httpd
# docker.io/amd64/httpd             The Apache HTTP Server Project
# docker.io/futdryt/httpd
# docker.io/ppc64le/httpd           The Apache HTTP Server Project
# docker.io/9af925e7043/httpd
# docker.io/arm64v8/httpd           The Apache HTTP Server Project
# docker.io/arm32v7/httpd           The Apache HTTP Server Project
# docker.io/i386/httpd              The Apache HTTP Server Project
# docker.io/s390x/httpd             The Apache HTTP Server Project
# docker.io/tugboatqa/httpd         The Apache HTTP Server Project
# docker.io/signiant/httpd          httpd (apache2) base container with a custom...
# docker.io/inventis/httpd          apache container with support for https only
# docker.io/armhf/httpd             The Apache HTTP Server Project
# docker.io/publici/httpd           httpd:latest
# docker.io/vzwingmadomatic/httpd   Service frontal de l'application de domotiqu...

# List all local images before downloading
podman images
# REPOSITORY  TAG         IMAGE ID    CREATED     SIZE

# Download image
podman pull docker.io/library/httpd
# Trying to pull docker.io/library/httpd:latest...
# Getting image source signatures
# Copying blob 9bd25d4f7b77 done   |
# Copying blob bc0965b23a04 done   |
# Copying blob 4f4fb700ef54 done   |
# Copying blob d7ad38c6dd97 done   |
# Copying blob 79b49624e34b done   |
# Copying blob 7d9f97915db2 done   |
# Copying config 494b2b45fd done   |
# Writing manifest to image destination
# 494b2b45fd74cbf7eb7dc9cfeda02b26c9450e26719afaf1914635832217c4ce

# List all local images before downloading
podman images
# REPOSITORY               TAG         IMAGE ID      CREATED       SIZE
# docker.io/library/httpd  latest      494b2b45fd74  5 months ago  151 MB

Lab: Run a container

# list all containers
podman ps
# CONTAINER ID  IMAGE       COMMAND     CREATED     STATUS      PORTS       NAMES

# run a con from an img
# -d: detach mode, detach the current terminal from the running container
# -t: allocates a pseudo-tty and attach to the standard input of the container.
# -p: Mapping Ports for External Usage
# an httpd port 80 can be mapped to the host port 8080
podman run -dt -p 8080:80/tcp docker.io/library/httpd

# confirm
podman ps
# CONTAINER ID  IMAGE                           COMMAND           CREATED         STATUS         PORTS                 NAMES
# d8cdeff2b178  docker.io/library/httpd:latest  httpd-foreground  28 seconds ago  Up 28 seconds  0.0.0.0:8080->80/tcp  zealous_perlman

Confirm via browser

podman_httpd01

debug by checking log

podman logs -l
# AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 10.88.0.2. Set the 'ServerName' directive globally to suppress this message
# AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 10.88.0.2. Set the 'ServerName' directive globally to suppress this message
# [Tue Dec 24 23:45:07.019966 2024] [mpm_event:notice] [pid 1:tid 1] AH00489: Apache/2.4.62 (Unix) configured -- resuming normal operations
# [Tue Dec 24 23:45:07.020107 2024] [core:notice] [pid 1:tid 1] AH00094: Command line: 'httpd -D FOREGROUND'
# 10.88.0.1 - - [24/Dec/2024:23:48:33 +0000] "GET / HTTP/1.1" 200 45
# 10.88.0.1 - - [24/Dec/2024:23:48:33 +0000] "GET /favicon.ico HTTP/1.1" 404 196

Stop a container

# list all con
podman ps
# CONTAINER ID  IMAGE                           COMMAND           CREATED        STATUS        PORTS                 NAMES
# d8cdeff2b178  docker.io/library/httpd:latest  httpd-foreground  7 minutes ago  Up 7 minutes  0.0.0.0:8080->80/tcp  zealous_perlman

# stop a con
podman stop d8cdeff2b178
# d8cdeff2b178

# confirm
podman ps
# CONTAINER ID  IMAGE       COMMAND     CREATED     STATUS      PORTS       NAMES

Run 2 cons with different ports

podman run -dt -p 8081:80/tcp docker.io/library/httpd
podman run -dt -p 8082:80/tcp docker.io/library/httpd

# confirm
podman ps
# CONTAINER ID  IMAGE                           COMMAND           CREATED         STATUS         PORTS                 NAMES
# 3fb8d076caae  docker.io/library/httpd:latest  httpd-foreground  13 seconds ago  Up 14 seconds  0.0.0.0:8081->80/tcp  amazing_nash
# 52e55e608970  docker.io/library/httpd:latest  httpd-foreground  11 seconds ago  Up 12 seconds  0.0.0.0:8082->80/tcp  wonderful_banzai

# stop one con
podman stop 52e55e608970 3fb8d076caae
# 3fb8d076caae
# 52e55e608970

# confirm
podman ps
# CONTAINER ID  IMAGE       COMMAND     CREATED     STATUS      PORTS       NAMES

Lab: Create container with a name

# create a con from an img with a name
podman create --name httpd-con docker.io/library/httpd

# confirm: it donot display in the running list, but all list
podman ps
# CONTAINER ID  IMAGE       COMMAND     CREATED     STATUS      PORTS       NAMES

podman ps -a
# CONTAINER ID  IMAGE                           COMMAND           CREATED         STATUS                         PORTS                 NAMES
# d8cdeff2b178  docker.io/library/httpd:latest  httpd-foreground  17 minutes ago  Exited (0) 9 minutes ago       0.0.0.0:8080->80/tcp  zealous_perlman
# 3fb8d076caae  docker.io/library/httpd:latest  httpd-foreground  7 minutes ago   Exited (0) About a minute ago  0.0.0.0:8081->80/tcp  amazing_nash
# 52e55e608970  docker.io/library/httpd:latest  httpd-foreground  7 minutes ago   Exited (0) 5 minutes ago       0.0.0.0:8082->80/tcp  wonderful_banzai
# 43d5903bae4a  docker.io/library/httpd:latest  httpd-foreground  3 minutes ago   Created                                              httpd-con

# Start the container
podman start httpd-con
# httpd-con

# confirm
podman ps
# CONTAINER ID  IMAGE                           COMMAND           CREATED        STATUS         PORTS       NAMES
# 43d5903bae4a  docker.io/library/httpd:latest  httpd-foreground  6 minutes ago  Up 44 seconds              httpd-con

Lab: Manage container using systemd

Steps:
- generate systemd unit file
- copy the unit file into the systemd dir
Purpose:
- Can enable the container as a service in ssytemd

# generate a unit file
podman generate systemd --new --files --name httpd-con
# /root/container-httpd-con.service

# copy the systemd unit file
cp /root/container-httpd-con.service /etc/systemd/system
# confirm
ll /etc/systemd/system/container-httpd-con.service
# -rw-r--r--. 1 root root 760 Dec 24 19:12 /etc/systemd/system/container-httpd-con.service
systemctl list-unit-files | grep httpd-con
# container-httpd-con.service                                            disabled

# enable the service
systemctl enable container-httpd-con.service
# Created symlink /etc/systemd/system/default.target.wants/container-httpd-con.service → /etc/systemd/system/container-httpd-con.service.

# start the service
systemctl start container-httpd-con.service

# confirm
systemctl status container-httpd-con.service
# ● container-httpd-con.service - Podman container-httpd-con.service
#    Loaded: loaded (/etc/systemd/system/container-httpd-con.service; enabled; vendor preset: disab>
#    Active: active (running) since Tue 2024-12-24 19:16:45 EST; 4s ago
#      Docs: man:podman-generate-systemd(1)
#  Main PID: 10137 (conmon)
#     Tasks: 1 (limit: 22890)
#    Memory: 2.5M
#    CGroup: /system.slice/container-httpd-con.service
#            └─10137 /usr/bin/conmon --api-version 1 -c fa69ce22071f7297ad4855fda45c76e236ecce2f605>
# Dec 24 19:16:44 serverhost systemd[1]: Starting Podman container-httpd-con.service...
# Dec 24 19:16:45 serverhost systemd[1]: Started Podman container-httpd-con.service.
# Dec 24 19:16:45 serverhost podman[9980]: fa69ce22071f7297ad4855fda45c76e236ecce2f605a4fb87551ede0>
# lines 1-13/13 (END)

Reboot and check if the service enable

systemctl status container-httpd-con.service
# ● container-httpd-con.service - Podman container-httpd-con.service
#    Loaded: loaded (/etc/systemd/system/container-httpd-con.service; enabled; ve>
#    Active: active (running) since Tue 2024-12-24 19:19:58 EST; 1min 12s ago
#      Docs: man:podman-generate-systemd(1)
#  Main PID: 1788 (conmon)
#     Tasks: 1 (limit: 22890)
#    Memory: 75.3M
#    CGroup: /system.slice/container-httpd-con.service
#            └─1788 /usr/bin/conmon --api-version 1 -c f867fcbc8fdfdc852dd28b9d06>

# Dec 24 19:19:56 serverhost systemd[1]: Starting Podman container-httpd-con.serv>
# Dec 24 19:19:58 serverhost systemd[1]: Started Podman container-httpd-con.servi>
# Dec 24 19:19:58 serverhost podman[1235]: f867fcbc8fdfdc852dd28b9d065d8c64f4c636>
# lines 1-13/13 (END)

Confirm in browser

podman_httpd_service

TOP

Note_Tech

Linux - Container: Package podman

Podman

Podman vs Docker

Common Podman Commands

Package and Service

Lab: Download Image

Lab: Run a container

Lab: Create container with a name

Lab: Manage container using systemd

Linux - Container: Package `podman`