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: 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.

This image provides DRBD (Distributed Replicated Block Device) user-space utilities, including drbdadm, drbdsetup, drbdmeta, drbdmon, and drbd-events-log-supplier. These utilities are used to configure, manage, and monitor DRBD resources in a cluster.

Note: This image does not include a shell or default command. It is intended to be used as a base image or with explicit commands. The utilities are located in /usr/sbin/.

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.

Verify utilities are available

Use drbdadm to display version information and validate that the image is working:

$ docker run --rm dhi.io/drbd-utils:<tag> /usr/sbin/drbdadm --version

Common usage patterns

Display DRBD configuration:

$ docker run --rm -v /path/to/drbd.conf:/etc/drbd.conf:ro dhi.io/drbd-utils:<tag> /usr/sbin/drbdadm dump all

Setup a DRBD resource:

$ docker run --rm --privileged -v /path/to/drbd.conf:/etc/drbd.conf:ro dhi.io/drbd-utils:<tag> /usr/sbin/drbdadm up <resource-name>

Monitor DRBD status:

$ docker run --rm dhi.io/drbd-utils:<tag> /usr/sbin/drbdmon

Image variants

Docker 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.

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 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.

Configuration

DRBD utilities read configuration from /etc/drbd.conf and /etc/drbd.d/*.conf. The default configuration file /etc/drbd.d/global_common.conf is included in the image. Mount your custom configuration files as volumes:

$ docker run --rm -v /path/to/drbd.conf:/etc/drbd.conf:ro -v /path/to/drbd.d:/etc/drbd.d:ro dhi.io/drbd-utils:<tag> /usr/sbin/drbdadm dump all

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 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.

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

This image has no default entrypoint or CMD. You must always specify the full path to the utility you want to run:

• /usr/sbin/drbdadm - Main DRBD administration tool
• /usr/sbin/drbdsetup - Low-level DRBD setup tool
• /usr/sbin/drbdmeta - DRBD metadata manipulation tool
• /usr/sbin/drbdmon - DRBD monitoring tool
• /usr/sbin/drbd-events-log-supplier - Event logging utility

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.