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Hermes is an asynchronous message broker built on top of Kafka. We provide reliable, fault tolerant REST interface for message publishing and adaptive push mechanisms for message sending.

See our 10-minute getting started guide with Docker: Getting started

Visit our page: hermes.allegro.tech

See our full documentation: http://hermes-pubsub.readthedocs.org/en/latest/

If you have any question or idea regarding the project, please feel free to reach us out using GitHub discussions.

hermes is published under Apache License 2.0.

For code formatting we use google-java-format. Following steps are required for optimal dev experience in IJ:

1. Download google-java-format plugin
2. Set custom VM options required for IJ plugin
3. Go to Settings > google-java-format and click Enable google java-format (should be checked by default)
4. Go to Settings > Tools > Actions on Save and enable Reformat code and Optimize imports for Java files

Each save should automatically trigger reformat.

If you want to debug the CLI check on macOS:

wget https://github.com/google/google-java-format/releases/download/v1.23.0/google-java-format_darwin-arm64
chmod a+x google-java-format_darwin-arm64
chmod a+x .github/scripts/check-google-java-format.sh
./.github/scripts/check-google-java-format.sh                                                                                                                     

or if you are on Linux:

wget https://github.com/google/google-java-format/releases/download/v1.23.0/google-java-format_linux-x86-64
chmod a+x google-java-format_linux-x86-64
chmod a+x .github/scripts/check-google-java-format.sh
./.github/scripts/check-google-java-format.sh        

You can also run the following command to fix formatting for the whole project:

./.github/scripts/check-google-java-format.sh --fix

Integration and slow integration tests use Testcontainers and require a Docker-compatible runtime. On macOS with Podman, export the following variables before running any test that requires containers:

export DOCKER_HOST="unix://$(podman machine inspect --format '{{.ConnectionInfo.PodmanSocket.Path}}')"
export TESTCONTAINERS_RYUK_DISABLED=true

Then run tests as usual, e.g.:

./gradlew slowIntegrationTest
./gradlew integrationTest

Podman VM resources: slowIntegrationTest spawns many containers concurrently. Configure your Podman VM with at least 8 CPUs and 10 GB of memory or container startup may fail unexpectedly:

podman machine stop
podman machine set --cpus 8 --memory 10240
podman machine start

Test reports are available at https://allegro.github.io/hermes/allure, and performance test results can be found at https://allegro.github.io/hermes/performance/.