openjre
OpenJRE Overview
Secure your stack with a hardened OpenJRE image freshly-built by Minimus. Minimus images always include the most up-to-date package version for all packages and dependencies contained in the image.
OpenJRE (open-source Java Runtime Environment) is used to run Java applications. It complements OpenJDK, which is used for building Java applications. OpenJRE includes the JVM (Java Virtual Machine) and core libraries needed to run Java applications, without the compiler javac. Use this image in Dockerfile as a secure runtime base for Java applications built with OpenJDK. See also the Minimus tutorial for Java and Minimus tips for multi-stage builds.
Try It Out
To take the Minimus OpenJDK image for a test run, we will require both OpenJDK and OpenJRE in our Dockerfile to keep the build and runtime environments separate and include only the compiled .class in the final image. Our test will also involve a Java project with a simple program that prints a welcome message.
First, create 2 files in your directory:
- Dockerfile
- MyMinimus.java
Save the following code to your Dockerfile:
# === Build Stage ===
FROM reg.mini.dev/openjdk AS builder
COPY MyMinimus.java /home/build/
WORKDIR /home/build/
RUN javac -d /home/build MyMinimus.java
# === Runtime Stage ===
FROM reg.mini.dev/openjre
COPY --from=0 /home/build/MyMinimus.class /app/
WORKDIR /app/
CMD ["java", "MyMinimus"]Save the following Java script to the file MyMinimus.java. Note that for Java to compile properly, the filename must match the public class name, so be sure to save the file as MyMinimus.java.
class MyMinimus
{
public static void main(String args[])
{
System.out.println("Welcome to MyMinimus!");
}
} Next, build the custom image and run it. Note that the period . specifies the current directory as the build context:
docker build -t minimus-java-app .
docker run minimus-java-appYou should see the greeting Welcome to MyMinimus! in your terminal.
Technical Considerations
The OpenJRE image provided by Minimus is a slim, security-hardened alternative to the public image from Docker Hub. The images are largely interchangeable, with a few differences as noted below.
OpenJRE built by Minimus:
- Runs as non-root by default for a security-first approach that protects against privilege escalation attacks. The public image runs as root.
- The entrypoint is null and the default CMD is
java. The public image uses an entrypoint script (/__cacert_entrypoint.sh) with the default CMDjshell. - There are some differences in the working directory and environment variables. Drill down on the version specification tab for details.
The Payoff
A hardened, minimal image that will remain more secure for the long run and accrue vulnerabilities at a slower rate.
- See the risk reduction dashboard for a detailed CVE comparison over the past 30 days.
- Review the compliance report to see the default hardening and security configurations for the image.
Terms & Info
Trademark
This catalog is published by Minimus. All product names, logos, and marks, other than those belonging to Minimus, shown are owned by their respective rights holders and appear here only to identify the open source software each image contains. Minimus claims no ownership of those marks and implies no affiliation with, endorsement by, certification by, or sponsorship by any rights holder.
Disclaimer
Images are provided "as-is" without warranty of any kind. "Hardened" refers to the security configuration applied at the time of build and does not constitute a guarantee of ongoing security or absence of vulnerabilities. The free tier is provided without support, SLA, or guaranteed patching timelines. Security updates may be applied to paid subscriptions before or instead of free tier images. By pulling or using any image you agree to our Terms of Use.