cloudimg OpenJDK 21 Dev Kit on Ubuntu 24.04
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OpenJDK 21 LTS with Maven, Gradle and dependency caches on a dedicated data volume.
A ready to use Java development workstation. You connect over SSH and use it to write, compile, test and package Java applications. This image is deliberately a workstation rather than a server: it runs no network service of any kind, so on a fresh virtual machine the only listening socket reachable from outside the machine is SSH on port 22. There is no web console and no login page, and consequently no credential of any kind ships in the image — there is nothing to authenticate against and nothing to rotate.
A runtime that keeps getting patched. The primary toolchain is OpenJDK 21 LTS taken from the Ubuntu 24.04 main pocket, which matters for two reasons. First, that build is licensed GPL-2.0 with the Classpath Exception, which is what makes it redistributable inside a commercial image; Oracle JDK is not, and is never installed here. Second, because it comes from main it is covered by Ubuntu security updates and is upgraded automatically by the unattended upgrades this image leaves enabled, so the JVM keeps receiving fixes for the life of the machine. Nothing is held or version pinned anywhere in the image, because holding a package is the quiet way to stop security updates arriving.
Verified, not merely asserted. At build time every installed OpenJDK package had its SHA-256 compared against the digest Ubuntu publishes in its cryptographically signed package index, the resolved version was recorded, and the running java was asserted to report that exact build rather than some other runtime shadowing it on the path. Apache Maven and Gradle are installed from their official upstream archives and verified against the SHA-512 and SHA-256 those projects publish. The exact builds that shipped are recorded on the machine.
Both build tools, both supported releases. Maven 3.9.16 and Gradle 9.6.1 are both installed, because real teams are split between them, and OpenJDK 17 LTS ships alongside 21 for projects that have not moved yet. Both toolchains are registered in a global Maven toolchains file, so a project can select either. Maven and Gradle are exposed through /usr/local/bin, which is on the default path, so a non interactive build over SSH works exactly like an interactive one.
Your work on its own volume. A dedicated data volume carries the Maven local repository, the Gradle home and a workspace directory, so the storage holding gigabytes of dependencies can be sized, snapshotted and grown independently of the operating system disk. The redirection is set in Maven's global settings file and by linking the administrator's home directories, rather than through an environment variable, so it holds for every user and for a project's own build wrapper. Dependency caches ship empty, so nothing another project resolved arrives with your machine.
Verify it before you trust it. A single command, cloudimg-java-selftest, writes a real multi class project, resolves a real dependency from Maven Central, runs a JUnit 5 test suite, packages a runnable jar, executes it and checks the values the program computed, builds the same sources again with Gradle, and proves cross target compilation by reading the class file version back out of the emitted bytecode.
The JDKs are distributed under the GNU General Public License version 2 with the Classpath Exception; Maven and Gradle are Apache-2.0. Every upstream licence and notice, including the complete legal tree each JDK ships and the full licence bodies its copyright file refers to, is shipped inside the image and indexed by a single notice file. There is no per CPU or per deployment software fee. Java is a registered trademark of Oracle and/or its affiliates and OpenJDK is used here nominatively under Oracle's OpenJDK trademark policy; Gradle is a trademark of Gradle, Inc. and Apache Maven is a trademark of The Apache Software Foundation. cloudimg is not affiliated with, sponsored by, or endorsed by Oracle, Gradle, Inc., The Apache Software Foundation or Canonical Ltd. cloudimg provides the packaging, the verified toolchain, the dedicated data volume layout, security patching, a paired deployment guide and 24/7 support with a guaranteed 24 hour response SLA.