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.

Deploy the operator

The operator runs in Kubernetes. Install the custom resource definitions, RBAC, and the operator deployment from the upstream bundle for your operator version, then point the deployment at the hardened image. Replace <version> with the operator version (for example 1.23.0) and <tag> with the matching image tag.

kubectl apply --server-side -f https://raw.githubusercontent.com/percona/percona-server-mongodb-operator/v<version>/deploy/bundle.yaml
kubectl set image deployment/percona-server-mongodb-operator \
  percona-server-mongodb-operator=dhi.io/percona-server-mongodb-operator:<tag>
kubectl rollout status deployment/percona-server-mongodb-operator

The operator serves Prometheus metrics on port 8080 and health probes on port 8081.

Deploy a Percona Server for MongoDB cluster

Create the users secret and a PerconaServerMongoDB custom resource. Replace <version> with the same operator version as above.

kubectl apply -f https://raw.githubusercontent.com/percona/percona-server-mongodb-operator/v<version>/deploy/secrets.yaml
kubectl apply -f https://raw.githubusercontent.com/percona/percona-server-mongodb-operator/v<version>/deploy/cr.yaml
kubectl get psmdb

The operator injects this image as the init container of every database pod. The init container runs /init-entrypoint.sh, which copies mongodb-healthcheck and the database entrypoint scripts into the shared /opt/percona volume that the database containers use. When the crVersion in the custom resource matches the operator version, the operator uses its own image for the init container, so no extra configuration is needed. To pin it explicitly, set spec.initImage to dhi.io/percona-server-mongodb-operator:<tag> in the custom resource.

For backups, sharding, monitoring, and other advanced configuration, see the Percona Operator for MongoDB documentation⁠.

Non-hardened images vs. Docker Hardened Images

• The operator binary is installed at /usr/bin/percona-server-mongodb-operator. The upstream path /usr/local/bin/percona-server-mongodb-operator resolves through a symlink, and it is also the image entrypoint. The upstream image sets no entrypoint.
• mongodb-healthcheck is installed at /usr/bin/mongodb-healthcheck. The upstream root path /mongodb-healthcheck resolves through a symlink, so /init-entrypoint.sh copies it into /opt/percona exactly as upstream does.
• The image runs as the nonroot user 65532. The upstream image runs as user 2. Percona's manifests don't pin runAsUser, so this doesn't affect standard deployments.
• The upstream image ships license texts under /licenses and Mozilla-licensed module sources under /lib/hashicorp. This image doesn't. License and provenance information is carried by the image SBOM and attestations instead.

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

  percona-server-mongodb-operator is an exception: runtime variants include bash and GNU coreutils, because the image also runs as the init container of database pods and its /init-entrypoint.sh is a bash script that uses install and cp to populate the shared /opt/percona volume.

• 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 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. percona-server-mongodb-operator is an exception: its runtime variants keep bash for the init container entrypoint script.