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kube-mgmt

FIPS 140-3Security

Sidecar for managing OPA instances in Kubernetes.

OverviewGuidesTags

Quick Start

Pull the latest version of this image from the Ghost registry. Pulling requires authentication — generate a token and run docker login first (see Authentication below).

Authentication

The Ghost catalog is public to browse, but pulling images requires an account. Generate a pull token below (or from your Account → Tokens page) — you'll get a ready-to-paste docker login command, then docker pull works.

The username is generated automatically (it looks like robot$<project>+<auto-id>, not the name you typed) and is included in the docker login command above. The secret is shown only once when you create the token.

Verify Signature

All Ghost images are signed with cosign. Verifying the signature before deployment ensures the image has not been tampered with.

Install cosign via brew install cosign or download from the Sigstore releases page.

Using This Image

Reference this image in your Dockerfile as a base layer:

FIPS 140-3 Compliance

This is a vendor-built FIPS-enabled image: its cryptography runs on FIPS 140-3 validated modules configured by the upstream vendor. You can inspect the image metadata:

StandardFIPS 140-3
Crypto moduleVendor-configured validated modules
CryptographyValidated modules only
Use caseGovernment, regulated industries, compliance workloads

Additional Notes

How to use this image

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: registry.ghost-prod.alphabravo.io/ghost-base/kube-mgmt:<tag>
  • Mirrored image: <your-namespace>/dhi-kube-mgmt:<tag>

For the examples, you must first use docker login registry.ghost-prod.alphabravo.io to authenticate to the registry to pull the images.

This image runs the kube-mgmt binary, a sidecar for managing OPA (Open Policy Agent) instances in Kubernetes. It syncs Kubernetes resources such as ConfigMaps and Secrets as OPA policies and data. It is designed to be deployed alongside OPA within a Kubernetes cluster.

For the following examples, replace <tag> with the image variant you want to run. To confirm the correct namespace and repository name of the mirrored repository, select View in repository.

Use kube-mgmt as the entrypoint and --version as the command to display version information.

On this page

Quick StartAuthenticationVerify SignatureUsing This ImageFIPS ComplianceAdditional Notes
$ docker run --rm registry.ghost-prod.alphabravo.io/ghost-base/kube-mgmt:<tag> --version

kube-mgmt is typically deployed in Kubernetes as a sidecar container alongside OPA using Helm charts or manifests. For detailed deployment instructions, configuration options, and integration with OPA, refer to the official documentation at https://github.com/open-policy-agent/kube-mgmt

Image variants

Ghost hardened images come in different variants depending on their intended use. Image variants are identified by their tag.

  • 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 a 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 tag 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.

To view the image variants and get more information about them, select the Tags tab for this repository, and then select a tag.

Migrate to a Ghost hardened image

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

ItemMigration note
Base imageReplace your base images in your Dockerfile with a Ghost hardened image.
Package managementNon-dev images, intended for runtime, don't contain package managers. Use package managers only in images with a dev tag.
Nonroot userBy default, non-dev images, intended for runtime, run as a nonroot user. Ensure that necessary files and directories are accessible to that user.
Multi-stage buildUtilize images with a dev tag for build stages and non-dev images for runtime. For binary executables, use a static image for runtime.
TLS certificatesGhost hardened images contain standard TLS certificates by default. There is no need to install TLS certificates.
PortsNon-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.
Entry pointGhost hardened images may have different entry points than images such as Docker Official Images. Inspect entry points for Ghost hardened images and update your Dockerfile if necessary.
No shellBy default, non-dev images, intended for runtime, don't contain a shell. Use dev images in build stages to run shell commands and then copy artifacts to the runtime stage.

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

    Ghost hardened images contain minimal packages in order to reduce the potential attack surface. You may need to install additional packages in your Dockerfile. To view if a package manager is available for an image variant, select the Tags tab for this repository. To view what packages are already installed in an image variant, select the Tags tab for this repository, and then select a tag.

    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.

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 Ghost 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 a nonroot user. Ensure that necessary files and directories are accessible to that user. You may need to copy files to different directories or change permissions so your application running as a nonroot user can access them.

To view the user for an image variant, select the Tags tab for this repository.

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.

To see if a shell is available in an image variant and which one, select the Tags tab for this repository.

Entry point

Ghost hardened images may have different entry points than images such as Docker Official Images.

To view the Entrypoint or CMD defined for an image variant, select the Tags tab for this repository, select a tag, and then select the Specifications tab.