How to start a docker container before run the test

zero_coding

I would like to setup a test environment for Scala project. In addition, I need to start Kafka, that is running in a docker container. Before the test is going to start, it should start first Kafka container.

I am using Scalatest and thinking about to start the Kafka container in the TestFixture, once before tests run.

The question is, which is the recommended way to start a container before running tests. I considered the Docker API, but not sure, it is the right way or not.

Krzysztof Atłasik

You can use testcontainers-scala, which is just a wrapper around testcontainers.

In your build.sbt add:

libraryDependencies += "com.dimafeng" %% "testcontainers-scala" % "0.25.0" % "test"
libraryDependencies += "org.apache.kafka" % "kafka-clients" % "2.2.0"

And then you can create spec:

import com.dimafeng.testcontainers.{ForAllTestContainer, GenericContainer}
import org.apache.kafka.clients.consumer.KafkaConsumer
import org.apache.kafka.common.serialization.{StringDeserializer, StringSerializer}
import org.scalatest.FlatSpec
import org.testcontainers.containers.Network
import org.testcontainers.utility.Base58


class KafkaSpec extends FlatSpec with ForAllTestContainer {

  final val KafkaPort = 9093

  override val container = GenericContainer("confluentinc/cp-kafka").configure{ c =>
    c.withNetwork(Network.newNetwork())
    c.withNetworkAliases("kafka-" + Base58.randomString(6))
    c.withExposedPorts(KafkaPort)
    c.withEnv("KAFKA_LISTENERS", "PLAINTEXT://0.0.0.0:" + KafkaPort + ",BROKER://0.0.0.0:9092")
    c.withEnv("KAFKA_LISTENER_SECURITY_PROTOCOL_MAP", "BROKER:PLAINTEXT,PLAINTEXT:PLAINTEXT")
    c.withEnv("KAFKA_INTER_BROKER_LISTENER_NAME", "BROKER")
    c.withEnv("KAFKA_BROKER_ID", "1")
    c.withEnv("KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR", "1")
    c.withEnv("KAFKA_OFFSETS_TOPIC_NUM_PARTITIONS", "1")
    c.withEnv("KAFKA_LOG_FLUSH_INTERVAL_MESSAGES", Long.MaxValue.toString)
    c.withEnv("KAFKA_GROUP_INITIAL_REBALANCE_DELAY_MS", "0")
  }


  it should "do something" in {

    val properties = new Properties()
    properties.put("bootstrap.servers", s"${container.containerIpAddress}:$KafkaPort")
    properties.put("group.id", "test")
    properties.put("key.deserializer", classOf[StringDeserializer])
    properties.put("value.deserializer", classOf[StringDeserializer])
    properties.put("key.serializer", classOf[StringSerializer])
    properties.put("value.serializer", classOf[StringSerializer])

    val kafkaConsumer = new KafkaConsumer[String, String](properties)
    ....

  }
}

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