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.

Start a Solr image

The default CMD starts Solr in standalone mode on port 8983 as UID/GID 65532 (solr). Mount /var/solr for persistence; the host directory must be owned by 65532:65532 before the container starts.

Basic usage

docker run -d --name solr -p 8983:8983 dhi.io/solr:<tag>

Verify the node is up:

curl http://localhost:8983/solr/admin/info/system?wt=json

With Docker Compose

services:
  solr:
    image: dhi.io/solr:<tag>
    ports:
      - "8983:8983"
    volumes:
      - solr-data:/var/solr

volumes:
  solr-data:

Environment variables

Refer to the Apache Solr documentation⁠ for full configuration and operational reference.

Common Solr use cases

Create and query a core

solr create provisions a default configset; a bare cores?action=CREATE API call fails with Can't find resource 'solrconfig.xml' because it expects the configset to already exist.

docker exec -it solr solr create -c demo

curl -X POST "http://localhost:8983/solr/demo/update?commit=true" \
  -H "Content-Type: application/json" \
  -d '[{"id": "1", "title": "Docker Hardened Solr", "category": "search"}]'

curl "http://localhost:8983/solr/demo/select?q=title:Solr&wt=json"

SolrCloud with ZooKeeper

services:
  zookeeper:
    image: zookeeper:3.9
    ports:
      - "2181:2181"
    environment:
      ZOO_MY_ID: 1

  solr-1:
    image: dhi.io/solr:<tag>
    ports:
      - "8983:8983"
    environment:
      ZK_HOST: zookeeper:2181
    depends_on:
      - zookeeper
    volumes:
      - solr-1-data:/var/solr

  solr-2:
    image: dhi.io/solr:<tag>
    ports:
      - "8984:8983"
    environment:
      ZK_HOST: zookeeper:2181
    depends_on:
      - zookeeper
    volumes:
      - solr-2-data:/var/solr

volumes:
  solr-1-data:
  solr-2-data:

Once both nodes are up, create a collection through the Collections API:

curl -X POST "http://localhost:8983/solr/admin/collections?action=CREATE&name=test&numShards=1&replicationFactor=2"

Non-hardened images vs. Docker Hardened Images

The hardened Solr image differs from the upstream solr Docker Official Image in three ways that affect migration:

• UID change — Upstream runs as UID 8983; DHI runs as UID 65532. Bind-mounted data directories require chown -R 65532:65532 <host-path> before the container starts. Named Docker volumes do not need this step.
• Optional Solr components removed — modules/, prometheus-exporter/, and cross-dc-manager/ are not present. None of these are loaded by Solr's default startup; removing them drops the vendored-Java CVE surface they bring in (Apache Tika, Hadoop/HDFS client, Kafka client, gRPC-Netty, etc.). If you need a specific module, copy the matching directory tree from the upstream Apache Solr release of the same version into /opt/solr/ in a child image. For Prometheus metrics, run apache/solr-prometheus-exporter as a sidecar (the upstream-recommended deployment).
• FIPS variants — JDK_JAVA_OPTIONS is pre-set to load BouncyCastle FIPS from the bootclasspath and use a BCFKS trust store. -Dorg.bouncycastle.fips.approved_only=false is set deliberately: Solr's CryptoKeys RSA keypair generation uses a SecureRandom path that BC FIPS rejects under strict mode, which would otherwise prevent startup. The BC FIPS provider is still loaded and supplies all crypto; only the strict approved-algorithms gate is relaxed. If your Solr configuration references PKCS12 (.p12) or JKS (.jks) keystores, convert them to BCFKS with keytool -importkeystore -srckeystore in.p12 -srcstoretype PKCS12 -destkeystore out.bcfks -deststoretype BCFKS -provider org.bouncycastle.jcajce.provider.BouncyCastleFipsProvider -providerpath /opt/bouncycastle/bc-fips-*.jar.

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.

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.