Prerequisites

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 Vault image

This Docker Hardened Vault image contains the Vault binary and the minimal runtime needed to operate the Vault server and CLI tools. It is intended to be used as a runtime image for running Vault or as a base for building custom Vault images. Runtime variants run as a nonroot user by default and do not include a shell or package manager. The image also includes tini⁠ so Vault runs as a well-behaved PID 1 child process.

Start a Vault image

The examples below show common ways to run Vault using the hardened image.

A quick note about --cap-add=IPC_LOCK

The --cap-add=IPC_LOCK flag in Docker grants the container the Linux CAP_IPC_LOCK capability, which allows processes inside the container to use the mlock system call. This is important for security-sensitive applications like HashiCorp Vault, which use mlock to lock memory and prevent secrets from being written to disk via swap. By default, Docker containers do not have this capability, so mlock will fail unless it's explicitly added. Using --cap-add=IPC_LOCK enables secure memory locking without requiring full root privileges or the use of the --privileged flag, making it a safer and more targeted way to allow necessary system capabilities. This is especially important in production environments where security and compliance matter.

This is explained in the Hashicorp Vault⁠ documentation further.

To run without the mlock capability, use the compat variant.

Basic (dev) usage — quick local testing only

The Vault "dev" mode is useful for local testing and CI but is insecure and should never be used in production. The dev server runs in-memory storage and automatically initializes and unseals Vault.

$ docker run --rm --name vault-dev -p 8200:8200 \
  --cap-add=IPC_LOCK \
  -e VAULT_DEV_ROOT_TOKEN_ID=root \
  dhi.io/vault:<tag> server -dev -dev-root-token-id=root -dev-listen-address=0.0.0.0:8200

After the container starts, you can interact with Vault on http://localhost:8200⁠ using the root token set above (here: "root").

Persistent file backend (single-node)

For simple persistent storage, run Vault with a file storage backend and mount a host volume. Create a small HCL config file on the host (e.g. ./vault.hcl):

listener "tcp" {
  address     = "0.0.0.0:8200"
  tls_disable = 1
}
storage "file" {
  path = "/vault/data"
}
ui = true

Run the container and mount the config and data directories:

$ docker run -d --name vault -p 8200:8200 \
  --cap-add=IPC_LOCK \
  -v /path/on/host/vault-data:/vault/data \
  -v /path/on/host/vault.hcl:/vault/config/vault.hcl:ro \
  dhi.io/vault:<tag> server -config=/vault/config/vault.hcl

Notes:

• The container process will write data to /vault/data inside the container; mount a host directory to persist data beyond the container lifecycle.
• In this mode, Vault must be initialized and unsealed before it can serve secrets. Use vault operator init and vault operator unseal (or an auto-unseal mechanism) as described in official Vault docs.

High-availability with Consul storage (example)

For HA setups, use a supported HA storage backend such as Consul. Example Docker Compose snippet (simplified):

services:
  consul:
    image: consul:1.14
    command: agent -server -bootstrap-expect=1 -client=0.0.0.0
    ports:
      - "8500:8500"
    volumes:
      - consul-data:/consul/data

  vault:
    image: dhi.io/vault:<tag>
    ports:
      - "8200:8200"
    depends_on:
      - consul
    volumes:
      - ./vault.hcl:/vault/config/vault.hcl:ro
    command: server -config=/vault/config/vault.hcl
    cap_add:
      - IPC_LOCK

volumes:
  consul-data: {}

Example vault.hcl for Consul backend (hosted/configured accordingly):

listener "tcp" {
  address     = "0.0.0.0:8200"
  tls_disable = 1
}
storage "consul" {
  address = "consul:8500"
  path    = "vault/"
}
ui = true

Environment variables

Common environment variables and options that are useful when running Vault inside a container:

Example using VAULT_LOCAL_CONFIG (quick single-host config):

$ docker run -d --name vault -p 8200:8200 \
  --cap-add=IPC_LOCK \
  -e VAULT_LOCAL_CONFIG='{"listener":{"tcp":{"address":"0.0.0.0:8200","tls_disable":1}},"storage":{"file":{"path":"/vault/data"}},"ui":true}' \
  -v /path/on/host/vault-data:/vault/data \
  dhi.io/vault:<tag> server -config=/vault/config

Using VAULT_LOCAL_CONFIG with the server -config flag instructs Vault to read the local config; when using complex configs prefer mounting a file.

Security notes and recommended practices

• Do not use dev mode in production. The dev server auto-unseals and is in-memory which is insecure for real workloads.
• For production, configure a proper storage backend (Consul, integrated storage in supported versions, or a cloud KMS-backed auto-unseal) and enable TLS. Mount certificates at runtime and set tls_disable = 0.
• Hardened images run as a nonroot user by default. Ensure any mounted volumes and configuration files are readable and writable by the nonroot user inside the container.

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

• Compat variants support more seamless usage of DHI as a drop-in replacement for upstream images, particularly for circumstances that the ultra-minimal runtime variant may not fully support. These images typically:

  • Run as a nonroot user
  • Improve compatibility with upstream helm charts
  • Include optional tools that are critical for certain use-cases

• 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 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.

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.