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High-performance dynamic image server in Java

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🍈 Cantaloupe

High-performance dynamic image server in Java


Get started with a release build.


Build & run

Command line

  • mvn clean compile exec:java -Dcantaloupe.config=...
    will build and run the project using the embedded web server listening on the port(s) specified in
  • mvn clean package -DskipTests
    will build a release JAR in the
    folder, which can be run via:

java -cp cantaloupe-{version}.jar -Dcantaloupe.config=... edu.illinois.library.cantaloupe.StandaloneEntry


  1. Add a new run configuration using the "Java Application" template or similar.
  2. Set the main class to
    and add the
    VM option.


Testing the code

and fill in whatever info you have.

The code tests are structured into three Maven profiles:

1. Tests with no dependencies

mvn clean test -Pnodeps
will run only the tests that have no dependencies on third-party services and do not require any external tools or libraries.

2. Tests with free dependencies

mvn clean test -Pfreedeps
will run all of the above tests, plus any that depend on open-source tools or libraries. These are the tests run in continuous integration. The following dependencies are required:
  • MinIO (for S3SourceTest & S3CacheTest)
  • FFmpeg (for FfmpegProcessorTest)
  • Grok (for GrokProcessorTest)
  • OpenJPEG (for OpenJpegProcessorTest)
  • TurboJPEG with Java binding (for TurboJpegProcessorTest)
  • Redis (for RedisCacheTest)

3. All tests

mvn clean test
will run all tests including the ones above. The following additional dependencies are required:
  • Kakadu native library (for KakaduNativeProcessorTest) - see the KakaduNativeProcessor section of the user manual for information.
  • A Microsoft Azure account


Because it can be a chore to install all of the dependencies needed to get all of the tests in the

profile passing, there is a
file available that will spin up all needed dependencies in separate containers, and run the tests in another container. From the project root directory, invoke:

docker-compose -f docker/{platform}/docker-compose.yml up --build --exit-code-from cantaloupe

Output testing

There is an output tester tool that enables visual inspection of image output.

Performance testing

Performance tests use JMH. Run them with

mvn clean test -Pbenchmark


The suggested process for contributing code changes is:

  1. Submit a "heads-up" issue in the tracker, ideally before beginning any work.
  2. Create a fork.
  3. Create a feature branch, starting from either
    (see the "Versioning" section.)
  4. Make your changes.
  5. Commit your changes (
    git commit -am 'Add some feature'
  6. Push the branch (
    git push origin feature/my-new-feature
  7. Create a pull request.

Other Notes

Configuration keys

Different application versions may require different configuration file keys. It's good practice to use a dedicated configuration file for each version. Key changes are documented in


Cantaloupe roughly uses semantic versioning. Major releases (n) involve major redesign that breaks backwards compatibility significantly. Minor releases (n.n) either do not break compatibility, or only in a minor way. Patch releases (n.n.n) are for bugfixes only.


Cantaloupe uses a basic version of the Gitflow branching model.

is the main branch that tracks the current state of the next non-bugfix release. Significant features branch off of that into feature branches (
), from which they can be integrated into a particular release.

When a major or minor version in

is ready for release, it merges into a
branch, where the release is tagged and the release archive is created.

Bugfixes that would increment a minor version of a release are applied to its release branch and merged back into



  1. Run the Maven Verifier plugin (
    mvn verify -DskipTests=true
  2. Run an OWASP dependency check (
    mvn org.owasp:dependency-check-maven:check
  3. Run Spotbugs (
    mvn clean compile spotbugs:spotbugs spotbugs:gui
  4. Run the Endpoint tests
  5. Finalize the code to be released, addressing any relevant milestone issues, TODOs, etc.
  6. Finalize the documentation, including the website, user manual, and change log


  1. Merge into
  2. Update the version in
    and commit this change
  3. git push origin release/x.x
  4. Wait for CI tests to pass
  5. Tag the release:
    git tag -a v{version} -m 'Tag v{version}'; git push --tags
  6. Wait for GitHub Actions to add the release artifact to the tag
  7. Add the change log to the release on GitHub
  8. Close the release's issue milestone
  9. Deploy the updated website (if necessary)


Cantaloupe is open-source software distributed under the University of Illinois/NCSA Open Source License; see the file LICENSE.txt for terms.

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