Image tag

Q: How deeply does Podman in Action: Secure, rootless containers for Kubernetes, microservices, and more cover image tag?

Explains shared image IDs, explicit versions, implicit latest, pushing, removal, and dangling images through command-line workflows.

As explained in Podman in Action: Secure, rootless containers for Kubernetes, microservices, and more

A container image tag is a mutable textual label used to refer to a particular image version within an image repository.

An image tag is a textual name attached to an image reference. Multiple tags can identify the same image ID, while different tags can distinguish application versions such as latest and 1.0. section 2.2.6

Use tags with Podman to name, publish, and manage image versions:

Inspect local repositories, tags, and image IDs with podman images. section 2.2.6
Add a registry-qualified name with podman tag myimage quay.io/rhatdan/myimage. section 2.2.6
Assign an explicit release tag, then push it with podman push quay.io/rhatdan/myimage:1.0. section 2.2.6
Remove a tag with podman rmi; storage is reclaimed only after the final tag is removed. section 2.2.7

Tagging a built image

Build with podman build -t quay.io/rhatdan/myimage ./myapp. Podman creates the latest tag implicitly. A later build can replace that name, leaving the previous image as a dangling <none>:<none> image that can be restored with podman tag or removed with podman rmi. section 2.3.2

$ podman images
REPOSITORY                      TAG        IMAGE ID        CREATED      SIZE
localhost/myimage            latest    2c7e43d88038   46 hours ago    462 MB
quay.io/rhatdan/myimage      latest    2c7e43d88038   46 hours ago    462 MB
registry.access.redhat
.com/ubi8/httpd-24         latest    8594be0a0b57    5 weeks ago    462 MB
registry.access.redhat
.com/ubi8                  latest    ad42391b9b46    5 weeks ago    234 MB

Compare multiple repository and tag names pointing to the same image ID. section 2.2.6

How Podman in Action: Secure, rootless containers for Kubernetes, microservices, and more covers it

Cover of Podman in Action: Secure, rootless containers for Kubernetes, microservices, and more

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Also explained in

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Road to KubernetesA container image tag is a human-readable identifier attached to an image reference to distinguish a version, environment, or release.
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Bootstrapping Microservices, Second Edition: With Docker, Kubernetes, GitHub Actions, and TerraformA Docker image tag is a human-readable label that identifies a particular image reference or version, optionally including a registry location.
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Kubernetes for DevelopersA version tag is an identifier appended to an image reference to distinguish a particular image version.
liveBook manning.com

Learn Docker in a Month of Lunches, Second EditionAn image tag is a human-readable name or label that identifies a container image reference.
liveBook manning.com

Kubernetes in Action, Second EditionAn image tag is a human-readable label appended to a container image name to identify a particular image reference or version.

Compare how 6 books explain image tag →

Related concepts

container imageconfigures · A container image is a packaged filesystem and configuration artifact from which a container can be created and run.
environment variableconfigured by · An environment variable is a named value supplied through an operating-system or process environment and made available to programs for runtime configuration or information.
image referencepart of · An image reference is a name that identifies a container image, optionally specifying its registry, repository, tag, or digest.
Docker Hubused by · Docker Hub is a hosted container registry and collaboration service for discovering, storing, sharing, and distributing container images and related artifacts.

This explainer was generated by Manning's knowledge graph from the text of Podman in Action: Secure, rootless containers for Kubernetes, microservices, and more. The section links point to the parts of the book it draws on.