Mapping Container Images To Chainguard

When converting FROM statements in a Dockerfile to use Chainguard images, follow these steps:

1. Use the dfc MCP server for automated conversion where available
2. Apply tag mapping rules
3. Look up unknown images using the ai-docs MCP server
4. Handle special cases (generic Linux bases, static binaries, FIPS)

Use the dfc MCP Server

If the dfc MCP server is available, use it to perform automated conversion. It handles registry rewriting, image name translation, and tag mapping automatically.

Use the convert_dockerfile tool to convert a full Dockerfile, or analyze_dockerfile to inspect the current state before converting.

When using dfc, always pass the organization name if you know it. If you don't, use ORG as a placeholder and remind the user to substitute their own.

Organization Name

Every Chainguard customer has their own organization namespace at cgr.dev:

cgr.dev/ORGANIZATION/image-name:tag

• For enterprise customers, use the customer's Chainguard organization name
• For free tier / public images, use chainguard

Check ~/.claude/chainguard-preferences.md if it exists, or ask the user if the organization name is unknown.

Tag Mapping Rules

Follow these rules when converting tags from upstream images to Chainguard:

1. chainguard-base always uses latest — never add a version or -dev suffix
2. No tag or non-semantic tag → latest
   • FROM node → FROM cgr.dev/ORGANIZATION/node:latest
   • FROM node:lts → FROM cgr.dev/ORGANIZATION/node:latest
3. Semantic version → truncate to major.minor
   • FROM node:14.17.3 → FROM cgr.dev/ORGANIZATION/node:14.17
4. Add -dev suffix when the stage has RUN commands (except chainguard-base)
   • FROM node:14 (stage has RUN) → FROM cgr.dev/ORGANIZATION/node:14-dev
   • FROM node:14 (no RUN) → FROM cgr.dev/ORGANIZATION/node:14
5. Final stage of a multi-stage build should use a non-dev image unless it has RUN commands

Examples:

• FROM node:14 → FROM cgr.dev/ORG/node:14-dev (if stage has RUN commands)
• FROM node:14.17.3 → FROM cgr.dev/ORG/node:14.17-dev (if stage has RUN commands)
• FROM debian:bullseye → FROM cgr.dev/ORG/chainguard-base:latest (always)
• FROM golang:1.19-alpine → FROM cgr.dev/ORG/go:1.19-dev (if stage has RUN commands)

Image Mapping Table

Special Cases

Generic Linux Bases

For generic Linux distributions (debian, ubuntu, alpine, fedora, centos, ubi*), use chainguard-base:

FROM cgr.dev/ORGANIZATION/chainguard-base:latest

• Always use the latest tag
• There is no latest-dev variant for chainguard-base
• chainguard-base provides apk for package installation

Static and Distroless Runtimes

For compiled binaries (Go, Rust, C) with no external runtime dependencies:

# Build stage
FROM cgr.dev/ORGANIZATION/go:latest-dev AS builder
# ... build with CGO_ENABLED=0 for fully static ...

# Runtime stage
FROM cgr.dev/ORGANIZATION/static:latest

Note that CGO_ENABLED=0 is typically required for the static image. If the binary links against glibc, check images.chainguard.dev for a suitable dynamic runtime image.

FIPS Variants

If FIPS compliance is required (check ~/.claude/chainguard-preferences.md), append -fips to the image name:

• python → python-fips
• node → node-fips
• go → go-fips
• jdk → jdk-fips
• chainguard-base → chainguard-base-fips

For example: cgr.dev/ORGANIZATION/python-fips:latest-dev

Digest References

If the original FROM uses a digest reference, the converted image should also include a digest. The digest will naturally be different for the Chainguard image.

Example original:

FROM python:3.12-slim@sha256:a866731a6b71c4a194a845d86e06568725e430ed21821d0c52e4efb385cf6c6f

Should become something like:

FROM cgr.dev/ORGANIZATION/python:3.12-dev@sha256:<chainguard-digest>

To get the correct digest for the Chainguard image:

# With crane (prefer this if available)
crane digest cgr.dev/ORGANIZATION/python:3.12-dev

# Or with docker
docker pull cgr.dev/ORGANIZATION/python:3.12-dev
docker inspect --format='{{index .RepoDigests 0}}' cgr.dev/ORGANIZATION/python:3.12-dev

Looking Up Images with the ai-docs MCP Server

If you're unsure which Chainguard image to use, or need to verify an image exists and check its documentation, use the ai-docs MCP server:

• list_images() — see all available Chainguard images
• get_image_docs(image_name) — get documentation for a specific image
• search_docs(query) — search by technology, use case, or keyword

For example, to find the right image for a Laravel PHP application:

get_image_docs("php")
search_docs("PHP FPM Chainguard")

You can also check the Chainguard Image Directory directly:

https://images.chainguard.dev/directory/image/<image-name>/overview
https://images.chainguard.dev/directory/image/<image-name>/versions