jdk 21

Use it as a base image

Reference it in the FROM line of your Dockerfile. Nonroot, read-only root filesystem, built for amd64 and arm64.

FROM ghcr.io/quenchworks/images/jdk:21

Or pull it directly

docker pull ghcr.io/quenchworks/images/jdk:21

Version line

21

Latest line

17, 21, 25

Architectures

amd64, arm64

Runs as

nonroot (uid 1001)

Root filesystem

read-only

License

GPL-2.0-with-classpath-exception

Verify the supply chain

This image is cosign-signed and carries an SPDX SBOM and a SLSA build-provenance attestation on the same digest. Check all three before you build on it:

# 1. signature — built and signed by QuenchWorks CI
cosign verify ghcr.io/quenchworks/images/jdk:21 \
  --certificate-identity-regexp 'https://github.com/quenchworks/.+' \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com

# 2. SLSA build provenance — which workflow built it, from what
gh attestation verify oci://ghcr.io/quenchworks/images/jdk:21 --owner quenchworks

# 3. SPDX SBOM — the package inventory
gh attestation verify oci://ghcr.io/quenchworks/images/jdk:21 --owner quenchworks \
  --predicate-type https://spdx.dev/Document

See the SBOM & provenance guide for reading the SBOM and using these checks in CI.

Best-practice Dockerfile for 21

Compile and package the jar with the full JDK in the build stage, then run it on the slim jre base. The compiler and build outputs stay behind; only the jar ships.

1
# Build stage: compile and package the jar with the full JDK.
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FROM ghcr.io/quenchworks/images/jdk:21 AS build
3
USER root
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WORKDIR /app
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COPY . .
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RUN ["javac", "-d", "/app/out", "@sources.txt"]
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RUN ["jar", "--create", "--file", "/app/app.jar", "--main-class", "App", "-C", "/app/out", "."]
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# Runtime stage: run the jar on the slim JRE base, nonroot.
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FROM ghcr.io/quenchworks/images/jre:21 AS runtime
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WORKDIR /app
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COPY --from=build /app/app.jar /app/app.jar
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USER 1001
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EXPOSE 8080
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ENTRYPOINT ["java", "-Djava.io.tmpdir=/tmp", "-jar", "/app/app.jar"]

This Dockerfile is pinned to the 21 line. For the line-by-line walkthrough and ecosystem variants (npm/Yarn, pip/uv/Poetry, Maven/Gradle), see the Build a Java app guide.