oembed-proxy: Implement retries if fetching oembed fails

oembed-proxy/src/main/scala/no/ndla/oembedproxy/service/OEmbedServiceComponent.scala

@@ -8,47 +8,69 @@
 
 package no.ndla.oembedproxy.service
 
+import com.typesafe.scalalogging.StrictLogging
 import no.ndla.network.NdlaClient
+import no.ndla.network.model.HttpRequestException
 import no.ndla.oembedproxy.model.{OEmbed, OEmbedProvider, ProviderNotSupportedException}
-import sttp.client3.quick._
+import sttp.client3.quick.*
 
+import scala.annotation.tailrec
 import scala.concurrent.duration.DurationInt
-import scala.util.{Failure, Try}
+import scala.util.{Failure, Success, Try}
 import scala.concurrent.duration.FiniteDuration
 
 trait OEmbedServiceComponent {
   this: NdlaClient with ProviderService =>
   val oEmbedService: OEmbedService
 
-  class OEmbedService(optionalProviders: Option[List[OEmbedProvider]] = None) {
+  class OEmbedService(optionalProviders: Option[List[OEmbedProvider]] = None) extends StrictLogging {
     val remoteTimeout: FiniteDuration = 10.seconds
 
     private lazy val providers = optionalProviders.toList.flatten ++ providerService
       .loadProviders()
     private def getProvider(url: String): Option[OEmbedProvider] =
       providers.find(_.supports(url))
 
+    private val MaxFetchOembedRetries: Int = 3
+    @tailrec
     private def fetchOembedFromProvider(
         provider: OEmbedProvider,
         url: String,
         maxWidth: Option[String],
-        maxHeight: Option[String]
+        maxHeight: Option[String],
+        retryCount: Int
     ): Try[OEmbed] = {
       val uri = uri"${provider.requestUrl(url, maxWidth, maxHeight)}"
       ndlaClient.fetch[OEmbed](
         quickRequest
           .get(uri)
           .followRedirects(true)
           .readTimeout(remoteTimeout)
-      )
+      ) match {
+        case Success(oembed)                   => Success(oembed)
+        case Failure(ex: HttpRequestException) => Failure(ex)
+        case Failure(ex) if retryCount < MaxFetchOembedRetries =>
+          logger.error(
+            s"Failed to fetch oembed from provider ${provider.providerName} for url $url. Retrying ${retryCount + 1}/$MaxFetchOembedRetries.",
+            ex
+          )
+          fetchOembedFromProvider(
+            provider,
+            url,
+            maxWidth,
+            maxHeight,
+            retryCount + 1
+          )
+        case Failure(ex) => Failure(ex)
+      }
     }
 
     def get(url: String, maxWidth: Option[String], maxHeight: Option[String]): Try[OEmbed] = {
       getProvider(url) match {
         case None =>
           Failure(ProviderNotSupportedException(s"Could not find an oembed-provider for the url '$url'"))
         case Some(provider) =>
-          fetchOembedFromProvider(provider, url, maxWidth, maxHeight).map(provider.postProcessor(url, _))
+          fetchOembedFromProvider(provider, url, maxWidth, maxHeight, 0).map(provider.postProcessor(url, _))
       }
     }