rest probe endpoints(#108)

src/main/resources/application.conf

@@ -21,6 +21,11 @@ ksm {
 
 }
 
+server {
+  port = 8080
+  port = ${?SERVER_PORT}
+}
+
 parser {
   csv {
     delimiter = ","

src/main/scala/io/conduktor/ksm/AclSynchronizer.scala

@@ -1,8 +1,8 @@
 package io.conduktor.ksm
 
-import io.conduktor.ksm.source.SourceAcl
 import io.conduktor.ksm.notification.Notification
 import io.conduktor.ksm.source.{ParsingContext, SourceAcl}
+import io.conduktor.ksm.web.Probe
 import kafka.security.auth.{Acl, Authorizer, Resource}
 import org.slf4j.{Logger, LoggerFactory}
 
@@ -62,12 +62,13 @@ class AclSynchronizer(
     notification: Notification,
     numFailedRefreshesBeforeNotification: Int,
     readOnly: Boolean = false
-) extends Runnable {
+) extends Runnable with Probe {
 
   import AclSynchronizer._
 
   private var sourceAclsCache: Set[(Resource, Acl)] = _
   private var failedRefreshes: Int = 0
+  private var isRefreshFailing = false
 
   if (readOnly) {
     log.warn("""
@@ -84,6 +85,7 @@ class AclSynchronizer(
     Try(sourceAcl.refresh()) match {
       case Success(result) =>
         failedRefreshes = 0
+        isRefreshFailing = false
         result match {
           // the source has not changed
           case None =>
@@ -125,6 +127,7 @@ class AclSynchronizer(
       case Failure(e) =>
         // errors such as HTTP exceptions when refreshing
         failedRefreshes += 1
+        isRefreshFailing = true
         try {
           log.error("Exceptions while refreshing ACL source:", e)
           if(failedRefreshes >= numFailedRefreshesBeforeNotification){
@@ -147,4 +150,8 @@ class AclSynchronizer(
     sourceAcl.close()
     notification.close()
   }
+
+  override def isSuccessful: Boolean = {
+    !isRefreshFailing
+  }
 }

src/main/scala/io/conduktor/ksm/AppConfig.scala

@@ -64,6 +64,11 @@ class AppConfig(config: Config) {
     val readOnly: Boolean = ksmConfig.getBoolean("readonly")
   }
 
+  object Server {
+    private val serverConfig = config.getConfig("server")
+    val port: Int = serverConfig.getInt("port")
+  }
+
   object Parser {
     private val aclParserConfig = config.getConfig("parser")
     val csvDelimiter: Char =

src/main/scala/io/conduktor/ksm/KafkaSecurityManager.scala

@@ -2,6 +2,7 @@ package io.conduktor.ksm
 
 import com.typesafe.config.ConfigFactory
 import io.conduktor.ksm.parser.AclParserRegistry
+import io.conduktor.ksm.web.Server
 import org.slf4j.LoggerFactory
 
 import java.util.concurrent.atomic.AtomicBoolean
@@ -18,6 +19,7 @@ object KafkaSecurityManager extends App {
   var aclSynchronizer: AclSynchronizer = _
   val parserRegistry: AclParserRegistry = new AclParserRegistry(appConfig)
   val scheduler: ScheduledExecutorService = Executors.newScheduledThreadPool(1)
+  var server: Server = _
 
   // For backward compatibility, see https://github.com/conduktor/kafka-security-manager/issues/103
   val oldExtractConfig = sys.env.get("KSM_EXTRACT")
@@ -37,6 +39,7 @@ object KafkaSecurityManager extends App {
       appConfig.KSM.numFailedRefreshesBeforeNotification,
       appConfig.KSM.readOnly
     )
+    server = new Server(appConfig.Server.port, List(aclSynchronizer))
 
     Runtime.getRuntime.addShutdownHook(new Thread() {
       override def run(): Unit = {
@@ -54,6 +57,7 @@ object KafkaSecurityManager extends App {
         log.info(
           "Continuous mode: ACL will be synchronized every " + appConfig.KSM.refreshFrequencyMs + " ms."
         )
+        server.start()
         val handle = scheduler.scheduleAtFixedRate(
           aclSynchronizer,
           0,
@@ -68,13 +72,14 @@ object KafkaSecurityManager extends App {
     } finally {
       shutdown()
     }
-
   }
 
   def shutdown(): Unit = {
     log.info("Kafka Security Manager is shutting down...")
     isCancelled = new AtomicBoolean(true)
     aclSynchronizer.close()
+    if (server != null)
+      server.stop()
     scheduler.shutdownNow()
   }
 }

src/main/scala/io/conduktor/ksm/web/ProbeHandler.scala

@@ -0,0 +1,23 @@
+package io.conduktor.ksm.web
+
+import com.sun.net.httpserver.{HttpExchange, HttpHandler}
+
+trait Probe {
+  // implementation should be non blocking
+  def isSuccessful: Boolean
+}
+
+class ProbeHandler(probes: List[Probe]) extends HttpHandler {
+  override def handle(exc: HttpExchange): Unit = {
+    val checkup = probes.forall(p => p.isSuccessful)
+    val payload = Server.responseMapper
+      .createObjectNode()
+      .put("success", checkup)
+    val response = Server.responseMapper.writeValueAsString(payload)
+    val responseCode = if (checkup) 200 else 500
+    exc.sendResponseHeaders(responseCode, response.length())
+    val os = exc.getResponseBody
+    os.write(response.getBytes)
+    os.close()
+  }
+}

src/main/scala/io/conduktor/ksm/web/Server.scala

@@ -0,0 +1,29 @@
+package io.conduktor.ksm.web
+
+import com.fasterxml.jackson.databind.ObjectMapper
+import com.sun.net.httpserver.HttpServer
+import org.slf4j.LoggerFactory
+
+import java.net.InetSocketAddress
+import java.util.concurrent.Executors
+
+object Server {
+  val responseMapper = new ObjectMapper()
+}
+
+class Server(port: Int, livenessProbes: List[Probe]) {
+  private val log = LoggerFactory.getLogger(Server.getClass)
+  private val server = HttpServer.create(new InetSocketAddress(port), 0)
+  server.createContext("/api/probe/ready", new ProbeHandler(List()))
+  server.createContext("/api/probe/alive", new ProbeHandler(livenessProbes))
+
+  def start(): Unit = {
+    log.info("Staring server on {}", port)
+    server.setExecutor(Executors.newSingleThreadExecutor())
+    server.start()
+  }
+
+  def stop(): Unit = {
+    server.stop(0)
+  }
+}

src/test/scala/io/conduktor/ksm/AclSynchronizerTest.scala

@@ -242,6 +242,7 @@ class AclSynchronizerTest
       aclSynchronizer.run()
       dummyNotification.addedAcls.size shouldBe 3
       dummyNotification.removedAcls.size shouldBe 0
+      aclSynchronizer.isSuccessful shouldBe true
       eventually(timeout(3000 milliseconds), interval(200 milliseconds)) {
         simpleAclAuthorizer
           .getAcls() shouldBe Map(res1 -> Set(acl1, acl2), res2 -> Set(acl3))
@@ -251,6 +252,7 @@ class AclSynchronizerTest
       dummyNotification.reset()
       dummySourceAcl.setErrorNext()
       aclSynchronizer.run()
+      aclSynchronizer.isSuccessful shouldBe false
       dummyNotification.addedAcls.size shouldBe 0
       dummyNotification.removedAcls.size shouldBe 0
       dummyNotification.errorCounter shouldBe 1
@@ -264,6 +266,7 @@ class AclSynchronizerTest
       aclSynchronizer.run()
       dummyNotification.addedAcls.size shouldBe 1
       dummyNotification.removedAcls.size shouldBe 1
+      aclSynchronizer.isSuccessful shouldBe true
       eventually(timeout(3000 milliseconds), interval(200 milliseconds)) {
         simpleAclAuthorizer.getAcls() shouldBe Map(
           res1 -> Set(acl1),

src/test/scala/io/conduktor/ksm/web/ServerTest.scala

@@ -0,0 +1,60 @@
+package io.conduktor.ksm.web
+
+import org.scalatest.{BeforeAndAfterAll, FlatSpec}
+import skinny.http.{HTTP, Request}
+
+class LivenessTestProbe extends Probe {
+  var success = false;
+
+  override def isSuccessful: Boolean = {
+    success
+  }
+}
+
+class ServerTest extends FlatSpec with BeforeAndAfterAll {
+  private val livenessTestProbe1 = new LivenessTestProbe
+  private val livenessTestProbe2 = new LivenessTestProbe
+  private val testSubject =
+    new Server(7777, List(livenessTestProbe1, livenessTestProbe2))
+  private val testServerUrl = "http://localhost:7777";
+  private val testReadyEndpoint = testServerUrl + "/api/probe/ready"
+  private val testAliveEndpoint = testServerUrl + "/api/probe/alive"
+
+  override protected def beforeAll(): Unit = {
+    testSubject.start()
+  }
+
+  override protected def afterAll(): Unit = {
+    testSubject.stop()
+  }
+
+  "get ready probe endpoint" should "return 200 with success true" in {
+    val response = HTTP.get(Request(testReadyEndpoint))
+    assert(response.status == 200)
+    assert(new String(response.body) == "{\"success\":true}")
+  }
+
+  "get alive probe endpoint" should "return 200 with success true, if all probes are successful" in {
+    livenessTestProbe1.success = true
+    livenessTestProbe2.success = true
+    val response = HTTP.get(Request(testAliveEndpoint))
+    assert(response.status == 200)
+    assert(new String(response.body) == "{\"success\":true}")
+  }
+
+  "get alive probe endpoint" should "return 500 with success false, if some probes are un-successful" in {
+    livenessTestProbe1.success = true
+    livenessTestProbe2.success = false
+    val response = HTTP.get(Request(testAliveEndpoint))
+    assert(response.status == 500)
+    assert(new String(response.body) == "{\"success\":false}")
+  }
+
+  "get alive probe endpoint" should "return 500 with success false, if all probes are un-successful" in {
+    livenessTestProbe1.success = false
+    livenessTestProbe2.success = false
+    val response = HTTP.get(Request(testAliveEndpoint))
+    assert(response.status == 500)
+    assert(new String(response.body) == "{\"success\":false}")
+  }
+}