Implement simple health check mechanism

Change-Id: Ic4b8b59ced9dc19c9ebf26131036a9e1a752164f
Issue-ID: DCAEGEN2-659
Signed-off-by: Jakub Dudycz <jakub.dudycz@nokia.com>

6 files changed, 200 insertions, 5 deletions

diff --git a/hv-collector-health-check/pom.xml b/hv-collector-health-check/pom.xml
index 4072ec24..1e77adb0 100644
--- a/hv-collector-health-check/pom.xml
+++ b/hv-collector-health-check/pom.xml
@@ -14,7 +14,6 @@
 
     <properties>
         <skipAnalysis>false</skipAnalysis>
-        <failIfMissingUnitTests>false</failIfMissingUnitTests>
     </properties>
 
     <parent>
@@ -42,6 +41,11 @@
 
     <dependencies>
         <dependency>
+            <groupId>${project.parent.groupId}</groupId>
+            <artifactId>hv-collector-utils</artifactId>
+            <version>${project.parent.version}</version>
+        </dependency>
+        <dependency>
             <groupId>org.jetbrains.kotlin</groupId>
             <artifactId>kotlin-stdlib-jdk8</artifactId>
         </dependency>
@@ -53,5 +57,25 @@
             <groupId>io.arrow-kt</groupId>
             <artifactId>arrow-effects</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.spek</groupId>
+            <artifactId>spek-api</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.spek</groupId>
+            <artifactId>spek-junit-platform-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.projectreactor</groupId>
+            <artifactId>reactor-test</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 </project>
\ No newline at end of file
diff --git a/hv-collector-health-check/src/main/kotlin/org/onap/dcae/collectors/veshv/healthcheck/http/HealthCheckApiServer.kt b/hv-collector-health-check/src/main/kotlin/org/onap/dcae/collectors/veshv/healthcheck/api/HealthCheckApiServer.kt
index 9cab031a..b21d1871 100644
--- a/hv-collector-health-check/src/main/kotlin/org/onap/dcae/collectors/veshv/healthcheck/http/HealthCheckApiServer.kt
+++ b/hv-collector-health-check/src/main/kotlin/org/onap/dcae/collectors/veshv/healthcheck/api/HealthCheckApiServer.kt
@@ -17,21 +17,24 @@
  * limitations under the License.
  * ============LICENSE_END=========================================================
  */
-package org.onap.dcae.collectors.veshv.healthcheck.http
+package org.onap.dcae.collectors.veshv.healthcheck.api
 
 import arrow.effects.IO
 import ratpack.handling.Chain
-import ratpack.http.Status
 import ratpack.server.RatpackServer
 import ratpack.server.ServerConfig
+import java.util.concurrent.atomic.AtomicReference
 
 /**
  * @author Jakub Dudycz <jakub.dudycz@nokia.com>
  * @since August 2018
  */
-class HealthCheckApiServer {
+class HealthCheckApiServer(private val healthStateProvider: HealthStateProvider) {
+
+    private val healthState: AtomicReference<HealthState> = AtomicReference(HealthState.STARTING)
 
     fun start(port: Int): IO<RatpackServer> = IO {
+        healthStateProvider().subscribe(healthState::set)
         RatpackServer
                 .start {
                     it
@@ -43,7 +46,9 @@ class HealthCheckApiServer {
     private fun configureHandlers(chain: Chain) {
         chain
                 .get("healthcheck") { ctx ->
-                    ctx.response.status(Status.OK).send()
+                    healthState.get().run {
+                        ctx.response.status(responseCode).send(message)
+                    }
                 }
     }
 }
\ No newline at end of file
diff --git a/hv-collector-health-check/src/main/kotlin/org/onap/dcae/collectors/veshv/healthcheck/api/HealthState.kt b/hv-collector-health-check/src/main/kotlin/org/onap/dcae/collectors/veshv/healthcheck/api/HealthState.kt
new file mode 100644
index 00000000..3dddf1e7
--- /dev/null
+++ b/hv-collector-health-check/src/main/kotlin/org/onap/dcae/collectors/veshv/healthcheck/api/HealthState.kt
@@ -0,0 +1,34 @@
+/*
+ * ============LICENSE_START=======================================================
+ * dcaegen2-collectors-veshv
+ * ================================================================================
+ * Copyright (C) 2018 NOKIA
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.dcae.collectors.veshv.healthcheck.api
+
+import org.onap.dcae.collectors.veshv.utils.http.Status.Companion.OK
+import org.onap.dcae.collectors.veshv.utils.http.Status.Companion.SERVICE_UNAVAILABLE
+
+/**
+ * @author Jakub Dudycz <jakub.dudycz@nokia.com>
+ * @since August 2018
+ */
+enum class HealthState(val message: String, val responseCode: Int) {
+    HEALTHY("Healthy", OK),
+    STARTING("Collector is starting", SERVICE_UNAVAILABLE),
+    WAITING_FOR_CONSUL_CONFIGURATION("Waiting for consul configuration", SERVICE_UNAVAILABLE),
+    CONSUL_CONFIGURATION_NOT_FOUND("Consul configuration not found", SERVICE_UNAVAILABLE)
+}
diff --git a/hv-collector-health-check/src/main/kotlin/org/onap/dcae/collectors/veshv/healthcheck/api/HealthStateProvider.kt b/hv-collector-health-check/src/main/kotlin/org/onap/dcae/collectors/veshv/healthcheck/api/HealthStateProvider.kt
new file mode 100644
index 00000000..5cc09ccc
--- /dev/null
+++ b/hv-collector-health-check/src/main/kotlin/org/onap/dcae/collectors/veshv/healthcheck/api/HealthStateProvider.kt
@@ -0,0 +1,39 @@
+/*
+ * ============LICENSE_START=======================================================
+ * dcaegen2-collectors-veshv
+ * ================================================================================
+ * Copyright (C) 2018 NOKIA
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.dcae.collectors.veshv.healthcheck.api
+
+import org.onap.dcae.collectors.veshv.healthcheck.impl.HealthStateProviderImpl
+import reactor.core.publisher.Flux
+
+/**
+ * @author Jakub Dudycz <jakub.dudycz@nokia.com>
+ * @since August 2018
+ */
+interface HealthStateProvider {
+
+    operator fun invoke(): Flux<HealthState>
+    fun changeState(healthState: HealthState)
+
+    companion object {
+        val INSTANCE: HealthStateProvider by lazy {
+            HealthStateProviderImpl()
+        }
+    }
+}
diff --git a/hv-collector-health-check/src/main/kotlin/org/onap/dcae/collectors/veshv/healthcheck/impl/HealthStateProviderImpl.kt b/hv-collector-health-check/src/main/kotlin/org/onap/dcae/collectors/veshv/healthcheck/impl/HealthStateProviderImpl.kt
new file mode 100644
index 00000000..5056d2da
--- /dev/null
+++ b/hv-collector-health-check/src/main/kotlin/org/onap/dcae/collectors/veshv/healthcheck/impl/HealthStateProviderImpl.kt
@@ -0,0 +1,39 @@
+/*
+ * ============LICENSE_START=======================================================
+ * dcaegen2-collectors-veshv
+ * ================================================================================
+ * Copyright (C) 2018 NOKIA
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.dcae.collectors.veshv.healthcheck.impl
+
+import org.onap.dcae.collectors.veshv.healthcheck.api.HealthStateProvider
+import org.onap.dcae.collectors.veshv.healthcheck.api.HealthState
+import reactor.core.publisher.Flux
+import reactor.core.publisher.FluxProcessor
+import reactor.core.publisher.UnicastProcessor
+
+/**
+ * @author Jakub Dudycz <jakub.dudycz@nokia.com>
+ * @since August 2018
+ */
+internal class HealthStateProviderImpl : HealthStateProvider {
+
+    private val healthStateStream: FluxProcessor<HealthState, HealthState> = UnicastProcessor.create()
+
+    override fun invoke(): Flux<HealthState> = healthStateStream
+
+    override fun changeState(healthState: HealthState) = healthStateStream.onNext(healthState)
+}
diff --git a/hv-collector-health-check/src/test/kotlin/org/onap/dcae/collectors/veshv/healthcheck/impl/HealthStateProviderImplTest.kt b/hv-collector-health-check/src/test/kotlin/org/onap/dcae/collectors/veshv/healthcheck/impl/HealthStateProviderImplTest.kt
new file mode 100644
index 00000000..e9c487bf
--- /dev/null
+++ b/hv-collector-health-check/src/test/kotlin/org/onap/dcae/collectors/veshv/healthcheck/impl/HealthStateProviderImplTest.kt
@@ -0,0 +1,54 @@
+/*
+ * ============LICENSE_START=======================================================
+ * dcaegen2-collectors-veshv
+ * ================================================================================
+ * Copyright (C) 2018 NOKIA
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.dcae.collectors.veshv.healthcheck.impl
+
+import org.jetbrains.spek.api.Spek
+import org.jetbrains.spek.api.dsl.describe
+import org.jetbrains.spek.api.dsl.given
+import org.jetbrains.spek.api.dsl.it
+import org.jetbrains.spek.api.dsl.on
+import org.onap.dcae.collectors.veshv.healthcheck.api.HealthState
+import reactor.test.StepVerifier
+
+/**
+ * @author Jakub Dudycz <jakub.dudycz@nokia.com>
+ * @since August 2018
+ */
+object HealthStateProviderImplTest : Spek({
+    describe("Health state provider") {
+            val healthStateProviderImpl = HealthStateProviderImpl()
+            on("health state update") {
+                healthStateProviderImpl.changeState(HealthState.HEALTHY)
+                healthStateProviderImpl.changeState(HealthState.WAITING_FOR_CONSUL_CONFIGURATION)
+                healthStateProviderImpl.changeState(HealthState.WAITING_FOR_CONSUL_CONFIGURATION)
+                healthStateProviderImpl.changeState(HealthState.CONSUL_CONFIGURATION_NOT_FOUND)
+
+                it("should push new health state to the subscriber") {
+                    StepVerifier
+                            .create(healthStateProviderImpl().take(4))
+                            .expectNext(HealthState.HEALTHY)
+                            .expectNext(HealthState.WAITING_FOR_CONSUL_CONFIGURATION)
+                            .expectNext(HealthState.WAITING_FOR_CONSUL_CONFIGURATION)
+                            .expectNext(HealthState.CONSUL_CONFIGURATION_NOT_FOUND)
+                            .verifyComplete()
+                }
+            }
+    }
+})
\ No newline at end of file