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 milvus-etcd image

milvus-etcd⁠ is the etcd distribution maintained by the Milvus⁠ project as the metadata store for Milvus vector database deployments. The image contains the official etcd⁠ server together with the etcdctl and etcdutl tools, plus the Bitnami-compatible startup scripts under /opt/bitnami/scripts that render the etcd configuration from ETCD_* environment variables. This is the image the milvus-helm⁠ chart deploys as its etcd dependency. The packaged etcd server follows the newest upstream etcd 3.5.x patch release so security fixes land without waiting for a new tag of the packaging repository, so it can be ahead of the etcd version embedded in the milvusdb/etcd tags.

Because the container's entrypoint is a script, this image differs from most hardened runtime images: it includes bash and the minimal userland the scripts need (including yq). It still runs as a non-root user and contains no package manager.

Run the milvus-etcd container

The startup scripts refuse to start etcd without authentication unless you explicitly allow it, matching upstream behavior. To start a single development node (the client port is bound to loopback because the instance accepts unauthenticated requests):

docker run --rm -p 127.0.0.1:2379:2379 \
  -e ALLOW_NONE_AUTHENTICATION=yes \
  dhi.io/milvus-etcd:<tag>

To print the release version of the packaged etcd binary:

docker run --rm dhi.io/milvus-etcd:<tag> etcd --version

To secure the instance, set a root password instead of allowing unauthenticated access:

docker run --rm -p 2379:2379 \
  -e ETCD_ROOT_PASSWORD=<password> \
  dhi.io/milvus-etcd:<tag>

Configure milvus-etcd

Configuration follows the upstream milvusdb/etcd conventions: any etcd configuration flag⁠ can be set through its ETCD_* environment variable, and every supported variable can also be loaded from a file by appending _FILE to its name (for example ETCD_ROOT_PASSWORD_FILE=/run/secrets/etcd-root-password). If a configuration file exists at /opt/bitnami/etcd/conf/etcd.yaml, etcd starts with --config-file and the scripts update it with the rendered values.

Persistent state lives in /bitnami/etcd/data. Mount a volume there to keep the keyspace across container restarts (loopback-bound for the same reason as above):

docker run --rm -p 127.0.0.1:2379:2379 \
  -e ALLOW_NONE_AUTHENTICATION=yes \
  -v etcd-data:/bitnami/etcd \
  dhi.io/milvus-etcd:<tag>

The scripts also support the upstream cluster lifecycle features used by the milvus-helm chart, including ETCD_ON_K8S=yes for Kubernetes member discovery, ETCD_START_FROM_SNAPSHOT / ETCD_INIT_SNAPSHOT_FILENAME to bootstrap from a snapshot in /init-snapshot, and /opt/bitnami/scripts/etcd/snapshot.sh to write periodic snapshots to /snapshots.

Use with the milvus-helm chart

The milvus-helm chart consumes this image through its etcd dependency. Point the chart at the hardened image by overriding the image values:

etcd:
  image:
    registry: dhi.io
    repository: milvus-etcd
    tag: <tag>

The image keeps the upstream directory layout (/opt/bitnami/etcd, /bitnami/etcd/data), lifecycle scripts, and default user UID (1001), so probes, snapshots, and persistence settings from the chart work unchanged.

Non-hardened images vs. Docker Hardened Images

Key differences

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

  milvus-etcd is an exception to the no-shell rule: its entrypoint is a bash script, so the runtime variants ship bash and a minimal userland. They still run as a non-root user and contain no package manager.

• 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 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.

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

Most hardened images intended for runtime don't contain a shell nor any tools for debugging; milvus-etcd is an exception and ships bash, so docker exec into a running container works for basic inspection. The recommended method for deeper debugging of 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. milvus-etcd is an exception: its runtime variants ship bash because the entrypoint scripts require it. For other images, use dev images in build stages to run shell commands and then copy any necessary artifacts into the runtime stage, and 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.