How to use the command 'podman' (with examples)
Podman is a simple management tool that provides a command-line interface for managing pods, containers, and images. It is comparable to the Docker-CLI command-line tool and can be used as a drop-in replacement for Docker. Here, we will explore various use cases of the ‘podman’ command and understand how to utilize it effectively.
Use case 1: List all containers (both running and stopped)
Code:
podman ps --all
Motivation:
Listing all containers, including running and stopped ones, can be helpful for management and debugging. This command provides an overview of all the containers present on the system.
Explanation:
podman ps: This command lists all running containers by default.--all: This option lists all containers, including the ones that are stopped.
Example output:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ab12cd34ef56 nginx:latest nginx -g 5 minutes ago Up 3 minutes web_server
1a2b3c4d5e6f busybox:latest /bin/sh 10 minutes ago Exited (0) 5 minutes ago echo_container
Use case 2: Create a container from an image, with a custom name
Code:
podman run --name container_name image
Motivation:
Creating containers from images is a fundamental operation when working with Podman. Specifying a custom name for the container allows for easier management and identification.
Explanation:
podman run: This command creates and runs a new container.--name: This option assigns a custom name to the container.container_name: This argument specifies the desired name for the container.image: This argument specifies the image to use for creating the container.
Example output:
ab12cd34ef56
Use case 3: Start or stop an existing container
Code:
podman start|stop container_name
Motivation:
Starting or stopping containers is essential for managing their life cycle. This command allows users to control the status of existing containers.
Explanation:
podman start: This command starts a stopped container.podman stop: This command stops a running container.container_name: This argument specifies the name of the container to start or stop.
Example output:
Started container_name
Use case 4: Pull an image from a registry (defaults to Docker Hub)
Code:
podman pull image
Motivation:
Pulling images from a registry allows users to access and use them locally. By default, Podman pulls images from Docker Hub, the most popular container registry.
Explanation:
podman pull: This command pulls an image from a registry.image: This argument specifies the name and tag of the image to pull.
Example output:
Getting image source signatures
Copying blob sha256:abcd1234 to cache
...
...
Status: Downloaded newer image for image:latest
Use case 5: Display the list of already downloaded images
Code:
podman images
Motivation:
Having a clear overview of the images present locally can help with management and resource allocation. This command provides detailed information about the downloaded images.
Explanation:
podman images: This command lists all the downloaded images and their details.
Example output:
REPOSITORY TAG IMAGE ID CREATED SIZE
nginx latest abcd1234 5 minutes ago 69MB
busybox latest 1a2b3c4d5e6f 10 minutes ago 4.84MB
Use case 6: Open a shell inside an already running container
Code:
podman exec --interactive --tty container_name sh
Motivation:
Accessing the shell inside a running container allows for executing commands and interacting with the container’s environment. This command enables users to open a shell session within a container.
Explanation:
podman exec: This command executes a command inside a running container.--interactive: This option keeps STDIN open, allowing for an interactive session.--tty: This option allocates a pseudo-TTY.container_name: This argument specifies the name of the running container.sh: This argument represents the shell to be invoked within the container.
Example output:
/ #
Use case 7: Remove a stopped container
Code:
podman rm container_name
Motivation:
Removing stopped containers helps in freeing up resources and decluttering the system. This command allows for the removal of containers that are no longer needed.
Explanation:
podman rm: This command removes one or more stopped containers.container_name: This argument specifies the name of the stopped container to remove.
Example output:
container_name
Use case 8: Display the logs of one or more containers and follow log output
Code:
podman logs --follow container_name container_id
Motivation:
Accessing the logs of containers can help in troubleshooting and monitoring. This command displays the logs of one or multiple containers, and the --follow option allows for following the log output in real-time.
Explanation:
podman logs: This command displays the logs of one or more containers.--follow: This option continuously streams the log output.container_name container_id: These arguments specify the names or IDs of the containers whose logs should be displayed.
Example output:
2021/07/01 10:00:01 Container container_name: Successfully started.
2021/07/01 10:01:02 Container container_id: Exited with status code 0.
Conclusion:
The ‘podman’ command is a versatile tool that simplifies managing pods, containers, and images. By exploring the use cases mentioned above, users can gain a better understanding of its capabilities and leverage it effectively for their container-related tasks. Whether it is listing containers, creating them, pulling images, or accessing logs, ‘podman’ provides a comprehensive set of features for container management.
