log friendlier cause for k8s pod health (#67)

Co-authored-by: Jacob Gulotta <jacob.gulotta@gettyimages.com>

Author: jgulotta

health-k8s/src/main/scala/com/devsisters/shardcake/K8sPodsHealth.scala

@@ -1,11 +1,27 @@
 package com.devsisters.shardcake
 
+import com.coralogix.zio.k8s.client.{
+  DecodedFailure,
+  DeserializationFailure,
+  Gone,
+  HttpFailure,
+  InvalidEvent,
+  K8sFailure,
+  K8sRequestInfo,
+  NotFound,
+  RequestFailure,
+  Unauthorized,
+  UndefinedField
+}
 import com.coralogix.zio.k8s.client.model.FieldSelector
 import com.coralogix.zio.k8s.client.v1.pods.Pods
 import com.devsisters.shardcake.interfaces.{ Logging, PodsHealth }
+import com.coralogix.zio.k8s.model.pkg.apis.meta.v1.Status
 import zio._
 import zio.cache.{ Cache, Lookup }
 
+import java.lang
+
 object K8sPodsHealth {
 
   /**
@@ -31,11 +47,93 @@ object K8sPodsHealth {
                         .map(_.isDefined)
                         .tap(ZIO.unless(_)(logger.logWarning(s"$podAddress is not found in k8s")))
                         .catchAllCause(cause =>
-                          logger.logError(s"Error communicating with k8s ${cause.prettyPrint}").as(true)
+                          logger.logError(s"Error communicating with k8s ${cause.map(asException).prettyPrint}").as(true)
                         )
                     }
                   )
     } yield new PodsHealth {
       def isAlive(podAddress: PodAddress): UIO[Boolean] = cache.get(podAddress)
     }).toLayer
+
+  // K8sFailure is not an Exception which means an attempt to directly log it as a Cause will, by default, lose transitive causal information
+  // because we only log k8s communication failures and then report the pod as healthy, we want to propagate as much information as possible to users
+  // therefore we convert K8sFailure to an exception, keeping transitive causes in some form whenever they're available, and creating friendlier messages for the rest
+  private def asException(k8sFailure: K8sFailure) =
+    k8sFailure match {
+      case Unauthorized(requestInfo, message) =>
+        new K8sException(s"unauthorized trying to ${toLogString(requestInfo)}: $message")
+
+      case HttpFailure(requestInfo, message, code) =>
+        new K8sException(s"http failure $code trying to ${toLogString(requestInfo)}: $message")
+
+      case DecodedFailure(requestInfo, status, code) =>
+        new K8sException(s"decoded failure $code trying to ${toLogString(requestInfo)}: ${toLogString(status)}")
+
+      case DeserializationFailure(requestInfo, error) =>
+        error.tail.foldLeft(
+          new K8sException(s"deserialization failure trying to ${toLogString(requestInfo)}", error.head)
+        ) { (result, e) =>
+          result.addSuppressed(e)
+          result
+        }
+
+      case RequestFailure(requestInfo, reason) =>
+        new K8sException(s"request failure trying to ${toLogString(requestInfo)}", reason)
+
+      case InvalidEvent(requestInfo, eventType) =>
+        new K8sException(s"invalid event $eventType trying to ${toLogString(requestInfo)}")
+
+      case UndefinedField(field) =>
+        new K8sException(s"undefined field $field")
+
+      case Gone =>
+        new K8sException("gone")
+
+      case NotFound =>
+        new K8sException("not found")
+    }
+
+  private def toLogString(requestInfo: K8sRequestInfo) = {
+    val sb = new lang.StringBuilder()
+
+    sb.append(requestInfo.operation)
+
+    sb.append(' ')
+
+    val typ = requestInfo.resourceType
+
+    sb.append(typ.group)
+    sb.append('/')
+    sb.append(typ.version)
+
+    sb.append(' ')
+
+    requestInfo.namespace.foreach { ns =>
+      sb.append(ns)
+      sb.append('/')
+    }
+    sb.append(typ.resourceType)
+    requestInfo.name.foreach { n =>
+      sb.append('/')
+      sb.append(n)
+    }
+
+    requestInfo.labelSelector.foreach { ls =>
+      sb.append(' ')
+      sb.append(ls.asQuery)
+    }
+
+    requestInfo.fieldSelector.foreach { fs =>
+      sb.append(' ')
+      sb.append(fs.asQuery)
+    }
+
+    sb.toString
+  }
+
+  private def toLogString(status: Status) =
+    status.message.getOrElse(status.reason.getOrElse("no explanation from k8s"))
+
+  private class K8sException(message: String, cause: Throwable = null)
+      extends RuntimeException(message, cause, true, false)
 }