"Distroless" Container Images.

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"Distroless" images contain only your application and its runtime dependencies.
They do not contain package managers, shells or any other programs you would expect to find in a standard Linux distribution.

For more information, see this talk (video).

Why should I use distroless images?

Restricting what's in your runtime container to precisely what's necessary for your app is a best practice employed by Google
and other tech giants that have used containers in production for many years.
It improves the signal to noise of scanners (e.g. CVE) and reduces the burden of establishing provenance to just what you need.

Distroless images are _very small_.
The smallest distroless image, gcr.io/distroless/static-debian13, is around 2 MiB.
That's about 50% of the size of alpine (~5 MiB), and less than 2% of the size of debian (124 MiB).

How do I use distroless images?

These images are built using bazel, but they can also be used through other Docker image build tooling.

What images are available?

The following images are currently published and updated by the distroless project (see SUPPORT_POLICY.md for support timelines)

These images refer to image indexes with references to all supported architectures. Architecture specific images can be directly referenced using an additional architecture suffix on the tag, like gcr.io/distroless/static-debian13:latest-amd64

Any other tags are considered deprecated and are no longer updated

Debian 13

Debian 13 distroless images use the debian UsrMerge scheme. If you use rules_distroless to add packages to an image, set mergedusr = True in <code class="ra0-md-code">apt.install</code>.

Debian 12

Why is distroless still using gcr.io instead of pkg.dev?

Distroless's serving infrastructure has moved to artifact registry but we still use the gcr.io domain. Users will get the benefits of the newer infrastructure without changing their builds.

How do I verify distroless images?

All distroless images are signed by cosign with ephemeral keys (keyless). We recommend verifying any distroless image you use before building your image. You can verify the keyless signature of any distroless image with:

cosign verify $IMAGE_NAME --certificate-oidc-issuer https://accounts.google.com --certificate-identity keyless@distroless.iam.gserviceaccount.com

Entrypoints

Note that distroless images by default do not contain a shell.
That means the Dockerfile ENTRYPOINT command, when defined, must be specified in vector form, to avoid the container runtime prefixing with a shell.

This works:

ENTRYPOINT ["myapp"]

But this does not work:

ENTRYPOINT "myapp"

For the same reasons, if the entrypoint is set to the empty vector, the CMD command should be specified in vector form (see examples below).
Note that by default static, base and cc images have the empty vector entrypoint. Images with an included language runtime have a language specific default (see: java, nodejs, python3).

Docker

Docker multi-stage builds make using distroless images easy.
Follow these steps to get started:

• Pick the right base image for your application stack.
• Write a multi-stage docker file.

Note: This requires Docker 17.05 or higher.

The basic idea is that you'll have one stage to build your application artifacts, and insert them into your runtime distroless image.
If you'd like to learn more, please see the documentation on multi-stage builds.

Examples with Docker

Here's a quick example for go:

# Start by building the application.
FROM golang:1.18 as build

WORKDIR /go/src/app
COPY . .

RUN go mod download
RUN CGO_ENABLED=0 go build -o /go/bin/app

# Now copy it into our base image.
FROM gcr.io/distroless/static-debian13
COPY --from=build /go/bin/app /
CMD ["/app"]

You can find other examples here:

• Java
• Python 3
• Go
• Node.js
• Rust

To run any example, go to the directory for the language and run:

docker build -t myapp .
docker run -t myapp

To run the Node.js Express example app and expose the container's ports:

npm install # Install express and its transitive dependencies
docker build -t myexpressapp . # Normal build command
docker run -p 3000:3000 -t myexpressapp

This should expose the Express application to your localhost:3000

Bazel

For full documentation on how to use bazel to generate Container images, see the bazel-contrib/rules_oci repository.

For documentation and example on how to create custom container images, see the GoogleContainerTools/rules_distroless repository.

Examples can be found in the GoogleContainerTools/rules_distroless repository.

Examples with Bazel

We have some examples on how to run some common application stacks in the /examples directory.
See here for:

• Java
• Python 3
• Go
• Node.js

See here for examples on how to complete some common tasks in your image:

• Adding and running as a non-root user
• Including Debian Packages
• Including CA certificates

See here for more information on how these images are built and released.

Base Operating System

Distroless images are based on Debian 13 (trixie). Images are explicitly tagged with Debian version suffixes (e.g. -debian13). Specifying an image without the distribution will currently select -debian13 images, but that will change in the future to a newer version of Debian. It can be useful to reference the distribution explicitly, to prevent breaking builds when the next Debian version is released.

Operating System Updates for Security Fixes and CVEs

Distroless tracks the upstream Debian releases, using Github actions to automatically generate a pull request when there are updates.

Debug Images

Distroless images are minimal and lack shell access. The :debug image set for each language provides a busybox shell to enter.

For example:

cd examples/python3/

edit the Dockerfile to change the final image to :debug:

FROM gcr.io/distroless/python3-debian13:debug
COPY . /app
WORKDIR /app
CMD ["hello.py", "/etc"]

then build and launch with a shell entrypoint:

docker build -t my_debug_image .

$ docker run --entrypoint=sh -ti my_debug_image

/app # ls
BUILD       Dockerfile  hello.py

> Note: If the image you are using already has a tag, for example gcr.io/distroless/java17-debian13:nonroot, use the tag debug- instead, for example gcr.io/distroless/java17-debian13:debug-nonroot.

> Note: ldd is not installed in the base image as it's a shell script, you can copy it in or download it.

Who uses Distroless?

• Kubernetes, since v1.15
• Knative
• Tekton
• Teleport
• BloodHound by SpecterOps
• K8gb - Kubernetes Global Load Balancer

If your project uses Distroless, send a PR to add your project here!

Community Discussion

• distroless-users Google Group
• Kubernetes slack #distroless channel