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.

What's included in this atlantis image

This Docker Hardened Atlantis image includes:

• atlantis — the Atlantis server binary
• terraform — a hardened Terraform build (from the Docker Hardened Terraform package) that Atlantis shells out to for plan and apply operations, on the 1.16 line that upstream Atlantis defaults to
• git and git-lfs — for cloning and updating pull request branches
• openssh-client — for cloning repositories over SSH
• GnuPG (gpg) — for verifying GPG-signed commits and tags

The image runs as the nonroot user and does not include OpenTofu (tofu) or conftest, both of which upstream Atlantis images bundle. See Non-hardened images vs Docker Hardened Images⁠ for details.

Run the atlantis container

Check the Atlantis version built into the image:

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

Print server flag help:

$ docker run --rm dhi.io/atlantis:<tag> server --help

Start the Atlantis server

Atlantis needs credentials for your VCS provider, a webhook secret, and a repository allowlist before it will accept pull request events. The following example configures Atlantis for GitHub:

$ docker run -d --name atlantis \
  -p 127.0.0.1:4141:4141 \
  -v atlantis-data:/home/nonroot/.atlantis \
  -e ATLANTIS_GH_USER=<github-username> \
  -e ATLANTIS_GH_TOKEN=<github-personal-access-token> \
  -e ATLANTIS_GH_WEBHOOK_SECRET=<webhook-secret> \
  -e ATLANTIS_REPO_ALLOWLIST='github.com/my-org/*' \
  -e ATLANTIS_ATLANTIS_URL=https://atlantis.example.com \
  dhi.io/atlantis:<tag>

Port 4141 serves the Atlantis web UI as well as the webhook endpoint, and that UI has no authentication unless you set --web-basic-auth (ATLANTIS_WEB_BASIC_AUTH). The example binds the port to 127.0.0.1 so only the reverse proxy that terminates TLS and forwards webhooks can reach it. Expose it more widely only once you have enabled basic auth or put your own authentication in front.

The volume keeps the data directory across restarts. Without it, pull request locks and saved plans are lost whenever the container is recreated.

The container's default command is server, so you don't need to specify it explicitly. Point your GitHub webhook at <ATLANTIS_ATLANTIS_URL>/events, and Atlantis starts commenting terraform plan and apply output on your pull requests.

Check that the server is healthy:

$ curl http://localhost:4141/healthz

For the full list of server flags and their environment variable equivalents (for other VCS providers, TLS, policy checks, and more) see the upstream server configuration reference⁠.

Persist Atlantis data

Atlantis stores its database, checked-out repositories, Terraform plans, and downloaded Terraform binaries in --data-dir, which defaults to ~/.atlantis. In this image, HOME is set to /home/nonroot, so the data directory resolves to /home/nonroot/.atlantis. Mount a volume there to persist state (including pull request locks) across container restarts:

$ docker run -d --name atlantis \
  -p 127.0.0.1:4141:4141 \
  -v atlantis-data:/home/nonroot/.atlantis \
  -e ATLANTIS_GH_USER=<github-username> \
  -e ATLANTIS_GH_TOKEN=<github-personal-access-token> \
  -e ATLANTIS_GH_WEBHOOK_SECRET=<webhook-secret> \
  -e ATLANTIS_REPO_ALLOWLIST='github.com/my-org/*' \
  -e ATLANTIS_ATLANTIS_URL=https://atlantis.example.com \
  dhi.io/atlantis:<tag>

Non-hardened images vs Docker Hardened Images

Key differences

Entry point

The hardened image drops the upstream docker-entrypoint.sh wrapper and runs the atlantis binary directly under dumb-init, which still reaps the terraform and git subprocesses that Atlantis spawns. If your existing workflow invokes the image with server <flags> (the common case), no change is needed:

$ docker run --rm dhi.io/atlantis:<tag> server --repo-allowlist='github.com/my-org/*' --gh-user=<user> --gh-token=<token>

If you relied on other implicit behavior from upstream's shell wrapper (for example, sourcing a custom docker-entrypoint.sh you mounted over the original), you must reimplement that logic outside the container, since this image runs the binary directly. The runtime variant does ship /bin/sh, so a mounted wrapper can still be run by overriding the entrypoint, but nothing sources one for you.

OpenTofu and Conftest

Upstream Atlantis images bundle OpenTofu (tofu) and conftest alongside Terraform so that repos configured with --default-tf-distribution=opentofu or with policy checks (--enable-policy-checks) work out of the box. This hardened image does not include tofu or conftest. If your repositories depend on either tool:

• Use a -dev variant as a build stage to download the upstream tofu/conftest release binaries, then copy them into your own image built FROM dhi.io/atlantis:<tag>. There is no hardened package for either tool, so the binaries stay unhardened and you keep them up to date yourself.
• Or run OpenTofu/Conftest processing outside of Atlantis (for example, in a separate CI step) before Atlantis plans or applies.

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

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 verify FIPS compliance, check the cryptographic module version in use by your Atlantis instance.

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

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.

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.