app/services/AmiMetadataLookup.scala

package services

import cats.syntax.either._
import com.amazonaws.services.ec2.AmazonEC2
import com.amazonaws.services.ec2.model.{DescribeImagesRequest, Image}

import scala.jdk.CollectionConverters._

case class AmiMetadata(architecture: String, debArchitecture: String)

class AmiMetadataLookup(ec2Client: AmazonEC2) {
  val archToDebArch = Map("x86_64" -> "amd64")

  def lookupMetadataFor(ami: String): Either[String, AmiMetadata] = {
    for {
      result <- Either
        .catchNonFatal {
          ec2Client.describeImages(
            new DescribeImagesRequest().withImageIds(ami)
          )
        }
        .leftMap[String](_ => "Call to describe images failed")
      imageDescription <- result.getImages.asScala.headOption
        .fold[Either[String, Image]](Left(s"No ami with ID $ami found"))(i =>
          Right(i)
        )
      architecture = imageDescription.getArchitecture
      debArchitecture = archToDebArch.getOrElse(architecture, architecture)
    } yield {
      AmiMetadata(architecture, debArchitecture)
    }

  }
}