Scala with Cats Code

POC for pure functional scala with cats. The applicaiton runs fs2 streams in parallel, one for producing events in kafka and the other for reading them and storing them in opensearch database. Hexagonal architecture is used to separate the business logic from the infrastructure.

Getting Started

You will need to have git, Java 11, and sbt installed.

Start SBT using the sbt command to enter SBT's interactive mode (> prompt):

$ sbt
[info] Loading global plugins from <DIRECTORY>
[info] Loading project definition from <DIRECTORY>
[info] Set current project to <PROJECT_NAME>

>

From the SBT prompt you can run the code in Main.scala:

> run
[info] Updating {file:<DIRECTORY>}cats-sandbox...
[info] Resolving jline#jline;2.14.4 ...
[info] Done updating.
[info] Compiling 1 Scala source to <DIRECTORY>...
[info] Running sandbox.Main
Hello Cats!
[success]

You can also start a Scala console (scala> prompt) to play with small snippets of code:

> console
[info] Starting scala interpreter...
[info]
Welcome to Scala 2.12.3 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_112).
Type in expressions for evaluation. Or try :help.

scala> import cats._, cats.implicits._, cats.data._
import cats._
import cats.implicits._
import cats.data._

scala> "Hello " |+| "Cats!"
res0: String = Hello Cats!

scala>

Press Ctrl+D to quit the Scala console and return to SBT interactive mode.

Press Ctrl+D again to quit SBT interactive mode and return to your shell.

Lint

run scalafix linter before pushing to GitHub

sbt runLinter

Run

run the docker-compose before launch Main.scala

Tests

To run Unit Tests:

sbt test

To run Integration Tests:

docker-compose up
sbt it:test
docker-compose down

Build Docker image

sbt docker:publishLocal

To run the application using our Docker image, run the following command:

cd /app
docker-compose up

TODO

• set avro serdes
• add tests (weaver)
• IT test
• fix kafka producer/consumer new connections