Hello-World for Lightbend Orchestration for Kubernetes

This project is an example for Lightbend Orchestration for Kubernetes.

What's this about?

This project consists of a simple Play application which has the SBT Reactive App plugin enabled. Using this plugin and the combination of Reactive CLI, deployment to a target runtime can be done in a seamless and timely manner.

At the point of writing the target runtime supported is Kubernetes, although the tool might be extended to support DC/OS and other target runtime.

Refer to DESIGN.md to see how the application is put together.

Pre-requisites

• Minikube installed and running with insecure registry enabled.
• Docker command line tools installed and enabled.
• OpenJDK 8 or Oracle Java 8
• SBT

Install Reactive CLI

See the Lightbend Orchestration for Kubernetes documentation.

Deploying to Minikube

There's two ways you can deploy to Minikube. There's a manual process which matches what you would typically do in a production environment, that is generating resources using rp and piping those to kubectl.

The SBT task, deploy minikube, automates this for you for local development.

Both are documented below.

Using SBT deploy minikube (Developer workflow)

Use the SBT task to deploy the application. This will build and deploy both applications to your Minikube. Three instances of clustered-impl will be started (see build.sbt for this configuration).

sbt 'deploy minikube'

You can also run this task directly from within SBT.

Using command line (Operations workflow)

Setup Minikube Docker environment variables.

$ eval $(minikube docker-env)

Clone this project from Github.

Go into the recently cloned project directory.

$ cd hello-reactive-tooling

Publish the project as Docker images into Minikube.

$ sbt frontend/docker:publishLocal simple-impl/docker:publishLocal clustered-impl/docker:publishLocal

Deploy the simple-impl to minikube using the following command. Note for the simple-impl we don't generate the Ingress resource as we don't wish to expose the endpoint outside of Kubernetes.

$ rp generate-kubernetes-resources simple-impl:0.0.1 --generate-services --generate-pod-controllers --env JAVA_OPTS="-Dplay.http.secret.key=simple" | kubectl apply -f -

Similarly, deploy the clustered-impl. We also won't expose clustered-impl outside of Kubernetes. We also scale the clustered-impl to 3 instances to test the cluster functionality.

$ rp generate-kubernetes-resources clustered-impl:0.0.1 --generate-services --generate-pod-controllers --pod-controller-replicas 3 --env JAVA_OPTS="-Dplay.http.secret.key=clustered" | kubectl apply -f -

Deploy the frontend to minikube using the following command.

$ rp generate-kubernetes-resources frontend:0.0.1 --generate-all --env JAVA_OPTS="-Dplay.http.secret.key=hereiam -Dplay.filters.hosts.allowed.0=$(minikube ip)" | kubectl apply -f -

Accessing the application

Run the following command to access the deployed frontend.

$ curl -vLk "https://$(minikube ip)/"

The frontend application exposes various other endpoints.

Accessing the simple-impl through frontend

Run the following command to access the simple-impl through frontend.

$ curl -vLk "https://$(minikube ip)/simple/hello"

The frontend will invoke the ServiceLocator provided by reactive-lib to locate simple-impl service.

Accessing the clustered-impl through frontend

Run the following command to access the clustered-impl through frontend.

$ curl -vLk "https://$(minikube ip)/clustered/hello"

The frontend will invoke the ServiceLocator provided by reactive-lib to locate clustered-impl service.

Accessing both clustered-impl and simple-impl through frontend

Run the following command.

$ curl -vLk "https://$(minikube ip)/forward/hello"

• The frontend will invoke the ServiceLocator provided by reactive-lib to locate clustered-impl service.
• The clustered-impl service will invoke Lagom client provided by the service-api. Internally Lagom will invoke the LagomServiceLocator provided by reactive-lib.

Performing SRV lookup through frontend

Run the following command, replacing <service-name> with the actual service name or the SRV entry you'd like to find. This command will return a list of address for a given service name.

$ curl -vLk "https://$(minikube ip)/srv/<service-name>"

Example:

$ curl -vLk "https://$(minikube ip)/srv/_http._tcp.simple-service.default.svc.cluster.local"

Run the following command, replacing <service-name> with the actual service name and <endpoint-name> with the actual endpoint name. This command will return a list of address for a given service name and endpoint name.

$ curl -vLk "https://$(minikube ip)/srv/<service-name>/<endpoint-name>"

Example:

$ curl -vLk "https://$(minikube ip)/srv/simple-service/http"