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Hello-World for Lightbend Orchestration for Kubernetes

The following project is created to test Lightbend Orchestration for Kubernetes from Play Scala and Lagom Scala's perspective.

The project seeks to assert the following functionality:

  • Deploying Play Scala and Lagom Scala application into Kubernetes.
  • Ensuring Play Scala can lookup Lagom Scala application using ServiceLocator provided by the reactive-lib project.
  • Ensuring Lagom Scala can establish a fully-formed Akka cluster using akka-cluster-bootstrap provided by the reactive-lib project.
  • Ensuring Lagom Scala can lookup another Lagom application using LagomServiceLocator provided by the reactive-lib project.

Setup

The project is split into 3 parts:

  • frontend: this is the Play Scala frontend.
  • clustered-api and clustered-impl: this is the Lagom Scala application which will form an Akka cluster, and message to the actor within the application will be sharded using Akka Cluster Sharding.
  • simple-api and simple-impl: this is simple, hello-world like Lagom Scala application.

Ingress access

Only frontend will be ingressed, and both Lagom applications will not be exposed (i.e. not accessible outside of Kubernetes).

frontend endpoints

The frontend application will provide these endpoints.

/

  • The / endpoint simply returns the word Hello.

/simple/:text

+--------------+          +----------------+
|              + -------> |                |
|  frontend    |          |  simple-impl   |
|              | <------- +                |
+--------------+          +----------------+
  • frontend will locate simple-impl service, and then will invoke the located endpoint which returns a simple text.
  • The returned text from simple-impl service is then returned to frontend.
  • frontend returns this text to the caller.

/clustered/:text

+--------------+          +-----------------+
|              + -------> |                 |
|  frontend    |          |  clustered-impl |
|              | <------- +                 |
+--------------+          +-----------------+
  • frontend will locate clustered-impl service, and then will invoke the located endpoint which returns a simple text.
  • The returned text from clustered-impl service is then returned to frontend.
  • frontend returns this text to the caller.

/forward/:text

+--------------+          +-----------------+          +----------------+
|              + -------> |                 + -------> |                |
|  frontend    |          |  clustered-impl |          |  simple-impl   |
|              | <------- +                 | <------- +                |
+--------------+          +-----------------+          +----------------+
  • frontend will locate clustered-impl service, and then will invoke the located endpoint.
  • The located endpoint within clustered-impl will then invoke simple-impl using the client API provided by simple-api.
  • The returned text from simple-impl is then returned to clustered-impl.
  • clustered-impl returns this text to frontend.
  • frontend returns this text to the caller.

/srv/:name

  • frontend will perform DNS SRV lookup for a given :name.
  • The :name can be the name of the service registered in Kubernetes, or the SRV name registered in Kube-DNS.
  • If found, the list of addresses will be returned, else 404 is returned.

/srv/:name/:endpoint

  • frontend will perform DNS SRV lookup for a given :name of a service, and the :endpoint name.
  • If found, the list of addresses will be returned, else 404 is returned.