How to use this image

Before you can use any Docker Hardened Image, you must mirror the image repository from the catalog to your organization. To mirror the repository, select either Mirror to repository or View in repository > Mirror to repository, and then follow the on-screen instructions.

All examples in this guide use the public image. If you've mirrored the repository for your own use (for example, to your Docker Hub namespace), update your commands to reference the mirrored image instead of the public one.

For example:

• Public image: dhi.io/<repository>:<tag>
• Mirrored image: <your-namespace>/dhi-<repository>:<tag>

For the examples, you must first use docker login dhi.io to authenticate to the registry to pull the images.

What's included in this Calico Hardened Image

This image ships the Calico combined binary at /usr/bin/calico, which packages the Calico components behind a single executable, and the CSI node driver registrar at /usr/bin/node-driver-registrar. The calico binary has the following subcommands:

The binary also changes behavior based on the name it is invoked as. The image provides /usr/bin/calicoctl, which runs the ctl subcommand, and /usr/bin/calico-ipam, which runs the Calico CNI IPAM plugin. Both are symlinks to /usr/bin/calico.

Start a Calico image

The image entry point is /usr/bin/calico, so you pass the subcommand directly as the container command.

To print the version:

docker run --rm dhi.io/calico:<tag> version

To view the available subcommands:

docker run --rm dhi.io/calico:<tag> --help

To run the CSI node driver registrar from the same image, override the entry point:

docker run --rm --entrypoint /usr/bin/node-driver-registrar dhi.io/calico:<tag> --version

Deploy Calico in Kubernetes

First follow the authentication instructions for DHI in Kubernetes⁠.

Calico runs as part of a full Calico installation. The Tigera Operator deploys and manages the Calico components that use this image. This image is not a standalone application and is intended to run alongside other Calico components.

Replace <your-namespace> with your organization's namespace, <secret name> with your Kubernetes image pull secret, and <tag> with the image variant you want to use.

The Tigera Operator manages all Calico components. To use hardened images, configure the Installation custom resource with your DHI registry settings (registry, imagePath, and imagePrefix). See the Calico Kube Controllers guides⁠ for the same Installation CR pattern and Helm install steps; they apply to this image and every other Calico component image.

Note: If you only have the Calico DHI image available, other Calico components may fail to start with ImagePullBackOff until their DHI images are also mirrored.

Image variants

Docker Hardened Images come in different variants depending on their intended use.

• Runtime variants are designed to run your application in production. These images are intended to be used either directly or as the FROM image in the final stage of a multi-stage build. These images typically:

  • Run as the nonroot user
  • Do not include a shell or a package manager
  • Contain only the minimal set of libraries needed to run the app

• Build-time variants typically include dev in the variant name and are intended for use in the first stage of a multi-stage Dockerfile. These images typically:

  • Run as the root user
  • Include a shell and package manager
  • Are used to build or compile applications

• FIPS variants include fips in the variant name and tag. They come in both runtime and build-time variants. These variants use cryptographic modules that have been validated under FIPS 140, a U.S. government standard for secure cryptographic operations. For example, usage of MD5 fails in FIPS variants.

Migrate to a Docker Hardened Image

To migrate your application to a Docker Hardened Image, you must update your Dockerfile. At minimum, you must update the base image in your existing Dockerfile to a Docker Hardened Image. This and a few other common changes are listed in the following table of migration notes.

The following steps outline the general migration process.

1. Find hardened images for your app.

   A hardened image may have several variants. Inspect the image tags and find the image variant that meets your needs.

2. Update the base image in your Dockerfile.

   Update the base image in your application's Dockerfile to the hardened image you found in the previous step. For framework images, this is typically going to be an image tagged as dev because it has the tools needed to install packages and dependencies.

3. For multi-stage Dockerfiles, update the runtime image in your Dockerfile.

   To ensure that your final image is as minimal as possible, you should use a multi-stage build. All stages in your Dockerfile should use a hardened image. While intermediary stages will typically use images tagged as dev, your final runtime stage should use a non-dev image variant.

4. Install additional packages

   Docker Hardened Images contain minimal packages in order to reduce the potential attack surface. You may need to install additional packages in your Dockerfile. Inspect the image variants to identify which packages are already installed.

   Only images tagged as dev typically have package managers. You should use a multi-stage Dockerfile to install the packages. Install the packages in the build stage that uses a dev image. Then, if needed, copy any necessary artifacts to the runtime stage that uses a non-dev image.

   For Alpine-based images, you can use apk to install packages. For Debian-based images, you can use apt-get to install packages.

When deploying with the Tigera Operator, configure the Installation CR so the operator pulls the Calico DHI images instead of upstream quay.io/calico/* references. See Calico Kube Controllers guides⁠ for the Installation CR fields.

Troubleshooting migration

The following are common issues that you may encounter during migration.

General debugging

The hardened images intended for runtime don't contain a shell nor any tools for debugging. The recommended method for debugging applications built with Docker Hardened Images is to use Docker Debug⁠ to attach to these containers. Docker Debug provides a shell, common debugging tools, and lets you install other tools in an ephemeral, writable layer that only exists during the debugging session.

Permissions

By default image variants intended for runtime, run as the nonroot user. Ensure that necessary files and directories are accessible to the nonroot user. You may need to copy files to different directories or change permissions so your application running as the nonroot user can access them.

Privileged ports

Non-dev hardened images run as a nonroot user by default. As a result, applications in these images can't bind to privileged ports (below 1024) when running in Kubernetes or in Docker Engine versions older than 20.10. To avoid issues, configure your application to listen on port 1025 or higher inside the container, even if you map it to a lower port on the host. For example, docker run -p 80:8080 my-image will work because the port inside the container is 8080, and docker run -p 80:81 my-image won't work because the port inside the container is 81.

No shell

By default, image variants intended for runtime don't contain a shell. Use dev images in build stages to run shell commands and then copy any necessary artifacts into the runtime stage. In addition, use Docker Debug to debug containers with no shell.

Entry point

Docker Hardened Images may have different entry points than images such as Docker Official Images. Use docker inspect to inspect entry points for Docker Hardened Images and update your Dockerfile if necessary.