Building Images

The steps of creating a container image can be stored in a plain text file commonly named Containerfile or Dockerfile. The syntax for Containerfile or Dockerfile is published by Docker Inc as the Dockerfile reference.

Note

It is recommended to name the file Dockerfile to keep it compatible with the docker command line interface.

Important

To avoid copy files by mistake to the container image, a file named .containerignore or .dockerignore should be used. It is recommended to name the file .dockerignore to keep it compatible with the docker command line interface.

Workflow

Given a Dockerfile, the container image can be created from Images > Build an Image.

Container image can also be created from the command line.

podman build \
--tag registry/namespace/repository:tag \
context

Note

registry

it is the location of the container image registry. For example docker.io for Docker Hub and quay.io for Red Had’s Quay.

namespace

it is usually represents a user or organization.

repository

it is the mandatory identifier for the container image.

tag

it is the optional identifier for variant of the container image.

context

it is the directory where the Dockerfile is located.

Example

Given the following Dockerfile

FROM docker.io/alpine:3.21.3

RUN apk add --no-cache python3

Running

podman build \
--tag my-tutorial/python:3.12 \
examples/python0

creates a container image named my-tutorial/python:3.12 that has Python installed.