Mastering Podman on Ubuntu: A Comprehensive Guide with Detailed Command Examples

Podman has become a popular alternative to Docker due to its flexibility, security, and rootless operation capabilities. This guide will walk you through the installation process and various advanced usage scenarios of Podman on Ubuntu, providing detailed examples for each command.

Table of Contents

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1. How to Install Podman

To get started with Podman on Ubuntu, follow these steps:

Update Package Index

Before installing any new software, it’s a good idea to update your package index to ensure you’re getting the latest version of Podman:

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sudo apt update

Install Podman

With your package index updated, you can now install Podman. This command will download and install Podman and any necessary dependencies:

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sudo apt install podman -y

Example Output:

kotlin

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Reading package lists… Done

Building dependency tree

Reading state information… Done

The following additional packages will be installed:

…

After this operation, X MB of additional disk space will be used.

Do you want to continue? [Y/n] y

…

Setting up podman (4.0.2) …

Verifying Installation

After installation, verify that Podman is installed correctly:

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podman –version

Example Output:

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podman version 4.0.2

2. How to Search for Images

Before running a container, you may need to find an appropriate image. Podman allows you to search for images in various registries.

Search Docker Hub

To search for images on Docker Hub:

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podman search ubuntu

Example Output:

lua

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INDEX NAME DESCRIPTION STARS OFFICIAL AUTOMATED

docker.io docker.io/library/ubuntu Ubuntu is a Debian-based Linux operating sys… 12329 [OK]

docker.io docker.io/ubuntu-upstart Upstart is an event-based replacement for the … 108 [OK]

docker.io docker.io/tutum/ubuntu Ubuntu image with SSH access. For the root p… 39

docker.io docker.io/ansible/ubuntu14.04-ansible Ubuntu 14.04 LTS with ansible 9 [OK]

This command will return a list of Ubuntu images available in Docker Hub.

3. How to Run Rootless Containers

One of the key features of Podman is the ability to run containers without needing root privileges, enhancing security.

Running a Rootless Container

As a non-root user, you can run a container like this:

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podman run –rm -it ubuntu

Example Output:

ruby

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root@d2f56a8d1234:/#

This command runs an Ubuntu container in an interactive shell, without requiring root access on the host system.

Configuring Rootless Environment

Ensure your user is added to the subuid and subgid files for proper UID/GID mapping:

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echo “$USER:100000:65536” | sudo tee -a /etc/subuid /etc/subgid

Example Output:

makefile

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user:100000:65536

user:100000:65536

4. How to Search for Containers

Once you start using containers, you may need to find specific ones.

Listing All Containers

To list all containers (both running and stopped):

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podman ps -a

Example Output:

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CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES

d13c5bcf30fd docker.io/library/ubuntu:latest 3 minutes ago Exited (0) 2 minutes ago confident_mayer

Filtering Containers

You can filter containers by their status, names, or other attributes. For instance, to find running containers:

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podman ps –filter status=running

Example Output:

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CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES

No output indicates there are no running containers at the moment.

5. How to Add Ping to Containers

Some minimal Ubuntu images don’t come with ping installed. Here’s how to add it.

Installing Ping in an Ubuntu Container

First, start an Ubuntu container:

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podman run -it –cap-add=CAP_NET_RAW ubuntu

Inside the container, install ping (part of the iputils-ping package):

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apt update

apt install iputils-ping

Example Output:

mathematica

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Get:1 http://archive.ubuntu.com/ubuntu focal InRelease [265 kB]

…

Setting up iputils-ping (3:20190709-3) …

Now you can use ping within the container.

6. How to Expose Ports

Exposing ports is crucial for running services that need to be accessible from outside the container.

Exposing a Port

To expose a port, use the -p flag with the podman run command:

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podman run -d -p 8080:80 ubuntu -c “apt update && apt install -y nginx && nginx -g ‘daemon off;'”

Example Output:

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54c11dff6a8d9b6f896028f2857c6d74bda60f61ff178165e041e5e2cb0c51c8

This command runs an Ubuntu container, installs Nginx, and exposes port 80 in the container as port 8080 on the host.

Exposing Multiple Ports

You can expose multiple ports by specifying additional -p flags:

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podman run -d -p 8080:80 -p 443:443 ubuntu -c “apt update && apt install -y nginx && nginx -g ‘daemon off;'”

Example Output:

wasm

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b67f7d89253a4e8f0b5f64dcb9f2f1d542973fbbce73e7cdd6729b35e0d1125c

7. How to Create a Network

Creating a custom network allows you to isolate containers and manage their communication.

Creating a Network

To create a new network:

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podman network create mynetwork

Example Output:

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mynetwork

This command creates a new network named mynetwork.

Running a Container on a Custom Network

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podman run -d –network mynetwork ubuntu -c “apt update && apt install -y nginx && nginx -g ‘daemon off;'”

Example Output:

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1e0d2fdb110c8e3b6f2f4f5462d1c9b99e9c47db2b16da6b2de1e4d9275c2a50

This container will now communicate with others on the mynetwork network.

8. How to Connect a Network Between Pods

Podman allows you to manage pods, which are groups of containers sharing the same network namespace.

Creating a Pod and Adding Containers

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podman pod create mypod

podman run -dt –pod mypod ubuntu -c “apt update && apt install -y nginx && nginx -g ‘daemon off;'”

podman run -dt –pod mypod ubuntu -c “apt update && apt install -y redis-server && redis-server”

Example Output:

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f04d1c28b030f24f3f7b91f9f68d07fe1e6a2d81caeb60c356c64b3f7f7412c7

8cf540eb8e1b0566c65886c684017d5367f2a167d82d7b3b8c3496cbd763d447

4f3402b31e20a07f545dbf69cb4e1f61290591df124bdaf736de64bc3d40d4b1

Both containers now share the same network namespace and can communicate over the mypod network.

Connecting Pods to a Network

To connect a pod to an existing network:

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podman pod create –network mynetwork mypod

Example Output:

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f04d1c28b030f24f3f7b91f9f68d07fe1e6a2d81caeb60c356c64b3f7f7412c7

This pod will use the mynetwork network, allowing communication with other containers on that network.

9. How to Inspect a Network

Inspecting a network provides detailed information about the network configuration and connected containers.

Inspecting a Network

Use the podman network inspect command:

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podman network inspect mynetwork

Example Output:

json

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[

{

“name”: “mynetwork”,

“id”: “3c0d6e2eaf3c4f3b98a71c86f7b35d10b9d4f7b749b929a6d758b3f76cd1f8c6”,

“driver”: “bridge”,

“network_interface”: “cni-podman0”,

“created”: “2024-08-12T08:45:24.903716327Z”,

“subnets”: [

{

“subnet”: “10.88.1.0/24”,

“gateway”: “10.88.1.1”

}

],

“ipv6_enabled”: false,

“internal”: false,

“dns_enabled”: true,

“network_dns_servers”: [

“8.8.8.8”

]

}

]

This command will display detailed JSON output, including network interfaces, IP ranges, and connected containers.

10. How to Add a Static Address

Assigning a static IP address can be necessary for consistent network configurations.

Assigning a Static IP

When running a container, you can assign it a static IP address within a custom network:

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podman run -d –network mynetwork –ip 10.88.1.100 ubuntu -c “apt update && apt install -y nginx && nginx -g ‘daemon off;'”

Example Output:

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f05c2f18e41b4ef3a76a7b2349db20c10d9f2ff09f8c676eb08e9dc92f87c216

Ensure that the IP address is within the subnet range of your custom network.

11. How to Log On to a Container with

Accessing a container’s shell is often necessary for debugging or managing running applications.

Starting a Container with

If the container image includes , you can start it directly:

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podman run -it ubuntu

Example Output:

ruby

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root@e87b469f2e45:/#

Accessing a Running Container

To access an already running container:

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podman exec -it <container_id>

Replace <container_id> with the actual ID or name of the container.

Example Output:

ruby

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root@d2f56a8d1234:/#

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