Image tag
An image tag is a textual label in a container image reference that identifies an image, often by version or variant, and may be mutable.
Road to Kubernetes
A container image tag is a human-readable identifier attached to an image reference to distinguish a version, environment, or release.
- How it is used
- Identifies images for runtime selection, staging, registry pushes, and deployment.
- How deep it goes
- Works through selecting, building, and deploying tags, but defers implementation of explicit production Deployment tags.
- Examples
- Uses Python and Node.js version tags, dual-tagged Docker builds, and a Compose configuration with a configurable tag.
- What you can do after
- Operate/configure image selection and labeling across Docker builds, Compose environments, and Kubernetes Deployments.
Bootstrapping Microservices, Second Edition: With Docker, Kubernetes, GitHub Actions, and Terraform
A Docker image tag is a human-readable label that identifies a particular image reference or version, optionally including a registry location.
- How it is used
- Names images for local commands and identifies the registry and version used to publish or run them.
- How deep it goes
- Works through build-time naming, retagging, verification, pushing, and cleanup; defers automatic version setting to a continuous deployment pipeline.
- Examples
- Uses `video-streaming:latest` locally and `bmdk1.azurecr.io/video-streaming:1` for a registry push.
- What you can do after
- Operate/configure it with Docker CLI commands to name, verify, publish, and run an image by tag.
Kubernetes for Developers
A version tag is an identifier appended to an image reference to distinguish a particular image version.
- How it is used
- Uses image tags to name, publish, select, and update container images in Docker and Kubernetes deployments.
- How deep it goes
- Explains naming conventions and rolling updates, but defers detailed rollout strategies and health checks.
- Examples
- Uses timeserver tags 1 and 2, complete Artifact Registry paths, Docker commands, and Deployment configuration.
- What you can do after
- Operate Docker and Kubernetes updates by tagging, pushing, and deploying a specific image version.
Learn Docker in a Month of Lunches, Second Edition
An image tag is a human-readable name or label that identifies a container image reference.
- How it is used
- Identifies application versions, registry images, and platform-specific variants during image building, pulling, and deployment.
- How deep it goes
- Explains naming defaults, version aliases, platform variants, and reproducibility trade-offs, but does not detail registry manifest internals.
- Examples
- Uses nginx release and Alpine tags, web-ping builds, registry aliases, and separate Arm and Intel image tags.
- What you can do after
- Apply it via Docker commands to build, retag, select, and stabilize container images across releases and platforms.
Read how Learn Docker in a Month of Lunches, Second Edition explains image tag →
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.
- How it is used
- Names locally built images, assigns registry-qualified references, publishes versions, and supports image cleanup.
- How deep it goes
- Explains shared image IDs, explicit versions, implicit latest, pushing, removal, and dangling images through command-line workflows.
- Examples
- Demonstrates latest and 1.0 tags, quay.io/rhatdan/myimage, podman tag, podman build, podman push, and podman images output.
- What you can do after
- Apply image tags via Podman CLI to name, version, push, inspect, and remove container images.
Kubernetes in Action, Second Edition
An image tag is a human-readable label appended to a container image name to identify a particular image reference or version.
- How it is used
- Selects a container image release or base-image variant when running Docker containers.
- How deep it goes
- Defines defaulting, version and variant naming, registry references, and local caching, but stops short of tag creation.
- Examples
- Uses Redis references redis:alpine and redis:7.4.1-alpine, plus busybox:latest in a docker run example.
- What you can do after
- Apply it via Docker commands to run a chosen image version or variant.
Read how Kubernetes in Action, Second Edition explains 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.
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