README.md

PUBSUB Scala

Utility code for using Google PubSub with Scala (Akka Streams). This repo follows the SemVer Specification.

• Current version: 1.0.0

Usage

Note: You need to create a google service account for pubsub to have the access keys for the project.

Configuration variables

You can put the relevant configuration variables in the ENV and create a pubsub config object:

val config: Option[PubSubConfig] = PubSubConfig.fromEnv(
  "PUBSUB_PRIVATE_KEY", "GOOGLE_PROJECT_ID",
  "PUBSUB_API_ID", "GOOGLE_SERVICE_ACCOUNT_EMAIL")

Or pass them directly (not recommended):

val config: PubSubConfig = PubSubConfig(
  "my-private-key", "my-google-ptoject-id",
  "my-pubsub-api-id", "my-google-service-account-email")

Or use a configuration file with the credentials and initialize the object later (e.g. application.conf).

Producer

Example of a producer/publisher:

import akka.actor.ActorSystem
import akka.stream.ActorMaterializer
import com.rhdzmota.pubsub.{PubSubConfig, PubSubProducer}

import scala.concurrent.Future
import scala.concurrent.ExecutionContext.Implicits.global

object Example {

  def main(args: Array[String]): Unit = {
    implicit val actorSystem = ActorSystem()
    implicit val actorMaterializer = ActorMaterializer()
    
    val pubSubConfig = PubSubConfig.fromEnv(
      "PUBSUB_PRIVATE_KEY", "GOOGLE_PROJECT_ID",
      "PUBSUB_API_ID", "GOOGLE_SERVICE_ACCOUNT_EMAIL")
      
    val exampleTopic = "my-pubsub-topic"
    val exampleData = "Data payload for pubsub"
    val exampleMessageId = "message-id-example"
    val exampleAttributes = Some(Map("key" -> "value"))
    
    val result: Option[Future[Seq[Seq[String]]]] = pubSubConfig.map(config => {
      val pubSubProducer = PubSubProducer(config)
      pubSubProducer.publish(exampleTopic, exampleData,
        exampleMessageId, exampleAttributes)
    })
    
    result match {
      case Some(future) => future.onComplete(println(_))
      case None => println("Missing env variables")
    }
  }
}

Consumer

Example of a consumer/subscriber:

import akka.actor.ActorSystem
import akka.stream.ActorMaterializer
import akka.stream.alpakka.googlecloud.pubsub.ReceivedMessage
import com.rhdzmota.pubsub.{PubSubConfig, PubSubConsumer}

object Example {

  def main(args: Array[String]): Unit = {
    implicit val actorSystem = ActorSystem()
    implicit val actorMaterializer = ActorMaterializer()
    
    val pubSubConfig = PubSubConfig.fromEnv(
      "PUBSUB_PRIVATE_KEY", "GOOGLE_PROJECT_ID",
      "PUBSUB_API_ID", "GOOGLE_SERVICE_ACCOUNT_EMAIL")
      
    val exampleSubscription = "my-subscription"
    val printMessageFunction: ReceivedMessage => Unit = 
      (receivedMessage: ReceivedMessage) => println(receivedMessage.message,toString)
      
    val graph = pubSubConfig.map(config => {
      val pubSubConsumer = PubSubConsumer(config)
      pubSubConsumer.subscribe(printMessageFunction)(exampleSubscription)
    })
    
    graph match {
      case Some(runnable) => runnable.run()
      case None => println("Missing env variables")
    }
  }
}