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/redis-operator:<tag>
• Mirrored image: <your-namespace>/dhi-redis-operator:<tag>

For the examples, you must first use docker login dhi.io to authenticate to the registry to pull the images.

Start a Redis Operator image

The entrypoint is /operator manager, the command is empty, and the working directory is /. Runtime images run as numeric user 65532. Dev images run as root and include a shell.

The process listens on:

• 8080/tcp for metrics (--metrics-bind-address, default :8080)
• 8081/tcp for probes (--health-probe-bind-address, default :8081). The probe paths are /healthz and /readyz.
• 9443/tcp for the admission webhook. The webhook server stays enabled unless ENABLE_WEBHOOKS is false.

The binary has no --version flag. Print the manager flags with --help. That output includes metrics-bind-address, health-probe-bind-address, and leader-elect:

docker run --rm dhi.io/redis-operator:<tag> --help

The same binary has manager and agent subcommands. Redis init containers run agent bootstrap. That command has a --sentinel flag, which writes Sentinel configuration instead of Redis configuration:

docker run --rm --entrypoint /operator dhi.io/redis-operator:<tag> agent bootstrap --help

Deploy Redis Operator on Kubernetes

Use the published Helm chart redis-operator version 0.26.1 (appVersion 0.26.0) from https://ot-container-kit.github.io/helm-charts⁠. This is the upstream OpsTree chart, not a catalog chart in this repository.

The Deployment command is /operator manager. With chart defaults the arguments include --leader-elect and, because metrics are enabled, --metrics-bind-address=:8080. The chart also passes --kube-client-timeout=60s and --max-concurrent-reconciles=3 from manager.config. The chart webhook default is false, so the rendered Deployment sets ENABLE_WEBHOOKS to false and omits container port 9443.

Set redisOperator.imageName, redisOperator.imageTag, and redisOperator.initContainerImageTag together. DHI tags have no v prefix. The tag shape is 0.26.0, not v0.26.0. An empty imageTag becomes v plus the chart appVersion (v0.26.0). initContainerImageTag defaults to v0.26.0, so changing only imageTag leaves the init container on that default.

redisOperator:
  imageName: dhi.io/redis-operator
  imageTag: "<tag>"
  initContainerImageTag: "<tag>"

Add the chart repository, then render the Deployment. In the output, the manager image and INIT_CONTAINER_IMAGE use the same name and tag:

helm repo add ot-helm https://ot-container-kit.github.io/helm-charts

helm template redis-operator ot-helm/redis-operator \
  --version 0.26.1 \
  --set redisOperator.imageName=dhi.io/redis-operator \
  --set redisOperator.imageTag=<tag> \
  --set redisOperator.initContainerImageTag=<tag>

Redis server and exporter images

This operator image does not contain Redis. Each Redis custom resource chooses its own server and exporter images. Set kubernetesConfig.image to dhi.io/redis:<tag> and redisExporter.image to dhi.io/redis-exporter:<tag>. The Redis image runs as numeric user 65532.

dhi.io/redis runtime images have no shell. When a Redis custom resource omits probes, operator v0.26.0 (internal/k8sutils/statefulset.go) injects readiness and liveness probes that run sh -ec around redis-cli ping. Those probes never succeed, so the pods stay unready. The image's /etc/redis/conf.d/docker.conf also leaves protected-mode on, so a client in another pod is refused. Exec /usr/local/bin/redis-cli directly for both probes, and mount a docker.conf that sets protected-mode no over that path. The data directory uses an emptyDir so this example does not need a StorageClass.

apiVersion: v1
kind: ConfigMap
metadata:
  name: example-redis-conf
data:
  docker.conf: |
    daemonize no
    bind 0.0.0.0 -::1
    protected-mode no
    logfile ""
---
apiVersion: redis.redis.opstreelabs.in/v1beta2
kind: Redis
metadata:
  name: example
spec:
  podSecurityContext:
    runAsUser: 65532
    fsGroup: 65532
  kubernetesConfig:
    image: dhi.io/redis:<tag>
  redisExporter:
    enabled: true
    image: dhi.io/redis-exporter:<tag>
  readinessProbe:
    exec:
      command:
        - /usr/local/bin/redis-cli
        - -h
        - 127.0.0.1
        - ping
    initialDelaySeconds: 2
    periodSeconds: 3
    failureThreshold: 20
  livenessProbe:
    exec:
      command:
        - /usr/local/bin/redis-cli
        - -h
        - 127.0.0.1
        - ping
    initialDelaySeconds: 15
    periodSeconds: 10
    failureThreshold: 6
  storage:
    volumeMount:
      volume:
        - name: redis-data
          emptyDir: {}
        - name: redis-conf
          configMap:
            name: example-redis-conf
      mountPath:
        - name: redis-data
          mountPath: /data
        - name: redis-conf
          mountPath: /etc/redis/conf.d/docker.conf
          subPath: docker.conf

This catalog does not publish a Redis Sentinel image. Set the Sentinel server image on the Redis Sentinel custom resource. Sentinel pods use the same default sh -ec probes, so a shell-less image stays unready until those probes exec the server binary directly. The operator's sh -c preStop hook is not on the Sentinel container. It is installed on cluster pods, and on replication pods that name a Sentinel service, and those pods need a shell or an explicit lifecycle hook.

Raw manifests

A manifest that leaves INIT_CONTAINER_IMAGE unset still falls back to the compiled default quay.io/opstree/redis-operator:latest. Set INIT_CONTAINER_IMAGE to the same dhi.io/redis-operator:<tag> you use for the manager.

Environment variables

This image sets SSL_CERT_FILE only. The Helm chart owns the other variables in this table. The image does not set ENABLE_WEBHOOKS, WATCH_NAMESPACE, INIT_CONTAINER_IMAGE, FEATURE_GATES, or SERVICE_DNS_DOMAIN.

Image tags

Debian publishes the bare major tag 0, along with 0.26 and 0.26.0, and distro-qualified tags such as 0.26.0-debian13. Alpine tags are distro-suffixed, for example 0.26.0-alpine3.24, and do not include the bare major tag. Dev tags add -dev. Those images run as root and include a shell. FIPS runtime tags add -fips, and FIPS dev tags add -fips-dev, on both Debian and Alpine.

Migrate from quay.io/opstree/redis-operator

quay.io/opstree/redis-operator:v0.26.0 and this image use the same entrypoint, /operator manager, and the same working directory, /. The upstream config user is 65532:65532. This image runs as numeric user 65532, the same uid and primary gid. Neither image defines a healthcheck.

On the Helm chart, set imageName, imageTag, and initContainerImageTag together, and use a DHI tag with no v prefix. On Redis custom resources, set kubernetesConfig.image to dhi.io/redis:<tag> and redisExporter.image to dhi.io/redis-exporter:<tag>, and apply the probe and protected-mode overrides in Redis server and exporter images⁠. Sentinel custom resources need the same probe override.

Troubleshooting

No version flag

There is no --version flag. Upstream ldflags are only -s -w, so the binary does not print a version string. Use --help, including agent bootstrap --help for the init-container command.

Webhooks

The chart default redisOperator.webhook is false, and the chart then sets ENABLE_WEBHOOKS=false. Turn the webhook on by setting redisOperator.webhook to true. Certificates are required only when that value is true. When the webhook is true and certmanager.enabled is false, Helm generates a self-signed certificate. When certmanager.enabled is true, cert-manager supplies the certificate.

Init-container tag

initContainerImageTag is separate from imageTag. The chart default for initContainerImageTag is v0.26.0. Set imageName, imageTag, and initContainerImageTag to the same DHI name and tag. A tag such as 0.26.0 is a DHI tag. v0.26.0 is the upstream chart default.

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

• 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.