Container Registry Language
5 exercises — Master the English vocabulary of container registries: image naming anatomy, digest pinning, multi-platform manifests, authentication, and vulnerability scanning.
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Quick reference: Container registry vocabulary
- Image name — registry/namespace/repository:tag (e.g., docker.io/library/node:20-alpine)
- Digest — SHA-256 hash of the image manifest; immutable; use for reproducible pinning
- Tag — mutable label;
latestand other tags can be reassigned at any time - Manifest list — OCI index mapping platform descriptors to per-platform image manifests
- CVE remediation — update base image → rebuild → rescan → document
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A runbook entry reads: "Pull the application image using its fully-qualified name: registry.company.com/platform/api-server:v2.5.1"
What does each component of this image reference represent?
A fully-qualified image name follows the pattern: registry/namespace/repository:tag.
Breaking down
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When the registry is omitted, Docker defaults to
Key vocabulary:
• registry — a server that stores and distributes container images (Docker Hub, ECR, GCR, GHCR)
• namespace — a grouping within a registry, typically an organisation, team, or project
• repository — a collection of images sharing a name but differing by tag
• tag — a human-readable label for a specific image version within a repository
• fully-qualified image name — the complete reference including registry, namespace, repository, and tag
Breaking down
registry.company.com/platform/api-server:v2.5.1:•
registry.company.com — the registry hostname (where the image is stored)•
platform — the namespace or organisation grouping related repositories•
api-server — the repository name (the image itself)•
v2.5.1 — the tag identifying a specific versionWhen the registry is omitted, Docker defaults to
docker.io. When the tag is omitted, Docker defaults to latest — a mutable tag that should not be used in production because it may reference different image content over time.Key vocabulary:
• registry — a server that stores and distributes container images (Docker Hub, ECR, GCR, GHCR)
• namespace — a grouping within a registry, typically an organisation, team, or project
• repository — a collection of images sharing a name but differing by tag
• tag — a human-readable label for a specific image version within a repository
• fully-qualified image name — the complete reference including registry, namespace, repository, and tag