Add new saveAppGraph sbt task

docs/shared-content-source/docs/modules/develop/pages/blueprints.adoc

@@ -248,3 +248,23 @@ You can explicitly verify if the blueprint connects all the streamlets correctly
 ----
 
 The blueprint is automatically verified when you use application-level targets, like `buildApp` and `runLocal`.
+
+You can visualize your blueprint as a graph by using:
+
+[source,bash]
+----
+  sbt printAppGraph
+----
+
+This task will print an ASCII graph to the console.
+
+Or use:
+
+[source,bash]
+----
+  sbt saveAppGraph
+----
+
+Which will save an ASCII graph to the `appGraph.txt` file under the `target/visuals/blueprint` folder of your Cloudflow project.
+
+You can also override the `appGraphSavePath` setting key to provide a new path for the App Graph file to save.

tools/cloudflow-sbt-plugin/src/main/scala/cloudflow/sbt/CloudflowApplicationPlugin.scala

@@ -52,5 +52,6 @@ object CloudflowApplicationPlugin extends AutoPlugin {
       packageOptions in (Compile, packageBin) +=
         Package.ManifestAttributes(new java.util.jar.Attributes.Name("Blueprint") -> blueprintFile.value.getName),
       verifyBlueprint := verifyBlueprint.value,
-      buildApp := cloudflowApplicationCR.value)
+      buildApp := cloudflowApplicationCR.value,
+      appGraphSavePath := target.value / "visuals" / "blueprint")
 }

tools/cloudflow-sbt-plugin/src/main/scala/cloudflow/sbt/CloudflowKeys.scala

@@ -68,6 +68,7 @@ trait CloudflowSettingKeys {
   val initialDebugPort =
     settingKey[Int]("Initial port number for debugging in runLocal. It will be increased by one for each Streamlet")
   val remoteDebugRunLocal = settingKey[Boolean]("Enable/Disable remote debugging for streamlets in runLocal")
+  val appGraphSavePath = settingKey[File]("The path where an application graph visualization should be saved.")
 }
 
 trait CloudflowTaskKeys {
@@ -82,6 +83,7 @@ trait CloudflowTaskKeys {
   val extraDockerInstructions = taskKey[Seq[sbtdocker.Instruction]]("A list of instructions to add to the dockerfile.")
   val verifyBlueprint = taskKey[Unit]("Verify Blueprint.")
   val printAppGraph = taskKey[Unit]("Print graph of all streamlets and how they are connected.")
+  val saveAppGraph = taskKey[File]("Save graph of all streamlets and how they are connected as a text file.")
   val build = taskKey[Unit]("Build the image.")
   val buildAndPublish = taskKey[Unit]("[Deprecated! Use buildApp] Build and publish the image.")
   val runLocal = taskKey[Unit]("Run the Cloudflow application in a local Sandbox.")

tools/cloudflow-sbt-plugin/src/main/scala/cloudflow/sbt/CloudflowLocalRunnerPlugin.scala

@@ -142,7 +142,7 @@ object CloudflowLocalRunnerPlugin extends AutoPlugin {
               host
             }
 
-            printAppLayout(resolveConnections(appDescriptor))
+            println(getAppLayout(resolveConnections(appDescriptor)))
             printInfo(runtimeDescriptorByProject, tempDir.toFile, topics, localConfig.message)
 
             val processes = runtimeDescriptorByProject.zipWithIndex.map {
@@ -177,7 +177,8 @@ object CloudflowLocalRunnerPlugin extends AutoPlugin {
             }
           }
         }.value,
-      printAppGraph := printApplicationGraph.value)
+      printAppGraph := printApplicationGraph.value,
+      saveAppGraph := saveApplicationGraph.value)
 
   def banner(bannerChar: Char)(name: String)(message: Any): Unit = {
     val title = s" $name "
@@ -310,7 +311,22 @@ object CloudflowLocalRunnerPlugin extends AutoPlugin {
       logger.error("LocalRunner: ApplicationDescriptor is not present. This is a bug. Please report it.")
       throw new IllegalStateException("ApplicationDescriptor is not present")
     }
-    printAppLayout(resolveConnections(appDescriptor))
+    println(getAppLayout(resolveConnections(appDescriptor)))
+  }
+
+  def saveApplicationGraph: Def.Initialize[Task[File]] = Def.task {
+    implicit val logger = streams.value.log
+    val _appDescriptor = applicationDescriptor.value
+    val appGraphDir = appGraphSavePath.value
+    val appGraphFile = appGraphDir / "appGraph.txt"
+    val appDescriptor = _appDescriptor.getOrElse {
+      logger.error("LocalRunner: ApplicationDescriptor is not present. This is a bug. Please report it.")
+      throw new IllegalStateException("ApplicationDescriptor is not present")
+    }
+    val layoutGraph = getAppLayout(resolveConnections(appDescriptor))
+    IO.write(appGraphFile, layoutGraph)
+    logger.info(s"App graph file is generated: $appGraphFile")
+    appGraphFile
   }
 
   def resolveConnections(appDescriptor: ApplicationDescriptor): List[(String, String)] = {
@@ -342,12 +358,19 @@ object CloudflowLocalRunnerPlugin extends AutoPlugin {
     }.toList
   }
 
+  @deprecated("Use 'getAppLayout' instead")
   def printAppLayout(connections: List[(String, String)]): Unit = {
     val vertices = connections.flatMap { case (a, b) => Seq(a, b) }.toSet
     val graph = Graph(vertices = vertices, edges = connections)
     println(GraphLayout.renderGraph(graph))
   }
 
+  def getAppLayout(connections: List[(String, String)]): String = {
+    val vertices = connections.flatMap { case (a, b) => Seq(a, b) }.toSet
+    val graph = Graph(vertices = vertices, edges = connections)
+    GraphLayout.renderGraph(graph)
+  }
+
   def scaffoldRuntime(
       projectId: String,
       descriptor: ApplicationDescriptor,

tools/cloudflow-sbt-plugin/src/sbt-test/sbt-cloudflow/app-graph-generation/build.sbt

@@ -0,0 +1,11 @@
+lazy val helloWorld = (project in file("."))
+  .enablePlugins(CloudflowApplicationPlugin, CloudflowAkkaPlugin)
+  .settings(
+    scalaVersion := "2.12.11",
+    name := "hello-world",
+    version := "0.0.1",
+    cloudflowDockerBaseImage := "adoptopenjdk/openjdk11:alpine",
+    libraryDependencies ++= Seq(
+      "ch.qos.logback" % "logback-classic" % "1.2.3"
+    )
+  )

tools/cloudflow-sbt-plugin/src/sbt-test/sbt-cloudflow/app-graph-generation/project/plugins.sbt

@@ -0,0 +1,7 @@
+sys.props.get("plugin.version") match {
+  case Some(x) => addSbtPlugin("com.lightbend.cloudflow" % "sbt-cloudflow" % x)
+  case _ => sys.error("""|The system property 'plugin.version' is not defined.
+                         |Specify this property using the scriptedLaunchOpts -D.""".stripMargin)
+}
+
+libraryDependencies += "com.lihaoyi" %% "ujson" % "0.9.5"

tools/cloudflow-sbt-plugin/src/sbt-test/sbt-cloudflow/app-graph-generation/src/main/blueprint/blueprint.conf

@@ -0,0 +1,5 @@
+blueprint {
+  streamlets {
+    hello-world = helloworld.HelloWorldShape
+  }
+}

tools/cloudflow-sbt-plugin/src/sbt-test/sbt-cloudflow/app-graph-generation/src/main/scala/helloworld/HelloWorld.scala

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2016-2021 Lightbend Inc. <https://www.lightbend.com>
+ *
+ * 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.
+ */
+package helloworld
+
+import akka.stream.scaladsl._
+import cloudflow.akkastream._
+import cloudflow.akkastream.scaladsl._
+import cloudflow.streamlets._
+
+class HelloWorldShape extends AkkaStreamlet {
+  val shape = StreamletShape.empty
+
+  def createLogic = new RunnableGraphStreamletLogic() {
+    def runnableGraph = 
+      Source
+        .single("Hello, world!")
+        .map(println)
+        .to(Sink.ignore)
+  }
+}
+

tools/cloudflow-sbt-plugin/src/sbt-test/sbt-cloudflow/app-graph-generation/test

@@ -0,0 +1,6 @@
+# save an app graph file to the default path
+> saveAppGraph
+$ exists target/visuals/blueprint/appGraph.txt
+
+# print an app graph to the console
+> printAppGraph