Purpose

The sos-endpoint accepts JSON as simple text and puts it on a topic.

Project Structure

• src/main/java - the service source code
• src/main/kubernetes - Kubernetes artifacts

This is a Spring Boot application which is deployed in Kubernetes. The container is built using the jib plugin for Maven.

Configuration

The application configuration is handled through a Kubernetes ConfigMap which is automatically read in by Spring Boot at deployment time. The following properties are supported:

• [required]mil.afdcgs.merlin.sos.kafka.bootstrap-server: the DNS name of the Kafka bootstrap server to connect to.
• [default 1] mil.afdcgs.merlin.sos.kafka.partition-count: the number of partitions for each created topic.
• [default 1] mil.afdcgs.merlin.sos.kafka.replica-count: the number of partition replicas to create across the cluster. This number can't exceed the number of nodes in the cluster.

Dependencies

The project uses these modules:

• spring-boot-starter-actuator - This module allows us to monitor the service health and metrics through HTTP.
• spring-kafka - a Spring library for connecting to Kafka and using it in a Spring-like fashion.
• spring-boot-starter-websocket - a Spring library for handing websockets.

Build

To build the project:

mvn clean install

This will create a Docker container image and upload it to the local Docker repository.

Testing

To send data to the endpoint using curl:

curl -v merlin.localdev.me/sos/sensor -H 'Content-Type:application/json' -d '{"name": "Elrond", "role": "Elf Lord"}'

Deployment

Local Development

For local development and testing, the process for making the built images available to the kubernetes cluster is dependent upon the Kubernetes

Note: If you're running on Docker Desktop then this step is not required.

On k3s with a local Docker registry desployed in the cluster:

$ docker push registry.localdev.me/sos-endpoint:latest

On k3s without a Docker registry deployed in the cluster:

$ docker save --output target/sos-endpoint-latest.tar registry.localdev.me/sos-endpoint:latest

$ sudo k3s ctr images import target/sos-endpoint-latest.tar

Create Kubernetes Artifcats

$ kubectl apply -f src/main/kubernetes/sos-endpoint.yaml

Uninstall

It can be removed with:

$ kubectl delete -f src/main/kubernetes/sos-endpoint.yaml