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.

About this image

This Docker Hardened Airflow image provides Apache Airflow in three variants:

Core (default) variant

The core variant is a minimal runtime image equivalent to the upstream Apache Airflow "slim" tags. It includes:

• Apache Airflow core components
• Essential Python runtime dependencies
• No provider packages (postgres, celery, etc.)
• No package management tools

Due to the lack of provider packages, the core variant has limited functionality on its own and is primarily intended as a base for customized Airflow installations.

Dev variant (-dev)

The dev variant is a build-time image that includes everything in the core variant plus:

• Package management tools
• Build dependencies and tools
• Source code used to build the core image
• Shell access for development and customization

Compat (-compat) variant

The compat variant is a batteries-included runtime image equivalent to the default upstream Apache Airflow images. It includes:

• Apache Airflow core components
• Essential Python runtime dependencies
• No package management tools
• The following Airflow provider packages:
  • amazon
  • celery
  • cncf-kubernetes
  • common-messaging
  • docker
  • elasticsearch
  • fab
  • ftp
  • git
  • google
  • grpc
  • hashicorp
  • http
  • microsoft-azure
  • mysql
  • odbc
  • openlineage
  • postgres
  • redis
  • sendgrid
  • sftp
  • slack
  • snowflake
  • ssh

Start an Airflow container

The following command will run the api-server using the core variant and expose the web interface on port 8080.

docker run -it --rm -p 8080:8080 -e AIRFLOW__API_AUTH__JWT_SECRET=test dhi.io/airflow:<tag> api-server

Installing Airflow providers onto the core image

Since the core image doesn't include provider packages, you'll need to use the dev variant to install them and then copy the installed providers to a core image for runtime use.

Basic provider installation workflow

The recommended approach is to use a multi-stage Dockerfile that:

1. Uses the dev variant to install providers
2. Copies the installed providers to the core variant for runtime

Here's a complete example that installs common providers:

# syntax=docker/dockerfile:1

# Stage 1: Install providers using dev variant
FROM dhi.io/airflow:<tag>-dev AS provider-build
WORKDIR /opt/airflow
# Install providers using pip
RUN pip install \
    --constraint constraints.txt \
    --prefix /opt/airflow-providers \
    apache-airflow-providers-postgres \
    apache-airflow-providers-celery \
    apache-airflow-providers-docker \
    apache-airflow-providers-kubernetes

# Stage 2: Runtime image with providers
FROM dhi.io/airflow:<tag> AS runtime
# Copy installed providers from build stage
COPY --from=provider-build /opt/airflow-providers /opt/airflow
# Copy your DAGs and configuration
COPY dags/ /opt/airflow/dags/
COPY airflow.cfg /opt/airflow/airflow.cfg

Providers requiring system dependencies

Some Airflow providers require system-level dependencies (installed via apt). For these cases, you'll need to:

1. Use a multi-stage build or a DHI customization (subscription required) to install the required system dependencies
2. Use the dev variant to install the provider packages
3. Copy the providers to your customized core image

Example workflow for a provider that needs system dependencies:

# syntax=docker/dockerfile:1

# Stage 1: Install providers using dev variant
FROM dhi.io/airflow:<tag>-dev AS provider-build
WORKDIR /opt/airflow
# Install provider that requires system dependencies
RUN pip install \
    --constraint constraints.txt \
    --prefix /opt/airflow-providers \
    apache-airflow-providers-oracle

# Stage 2: Use your customized DHI image with system dependencies
FROM dhi.io/airflow-custom:<tag> AS runtime
# Copy installed providers from build stage
COPY --from=provider-build /opt/airflow-providers /opt/airflow
# Copy your application files
COPY dags/ /opt/airflow/dags/

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 the 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. 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 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.

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

Docker 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.