Sort out versioning, release process, Travis builds (#1)

* Add versioning and release plugins

.travis.yml

@@ -0,0 +1,23 @@
+language: scala
+
+scala:
+  - 2.12.2
+jdk:
+  - oraclejdk8
+
+# Avoid triggering a duplicate build for PRs
+branches:
+  only:
+    - master
+
+# http://www.scala-sbt.org/0.13/docs/Travis-CI-with-sbt.html
+cache:
+  directories:
+    - $HOME/.ivy2/cache
+    - $HOME/.sbt/boot/
+before_cache:
+  - find $HOME/.ivy2 -name "ivydata-*.properties" -delete
+  - find $HOME/.sbt -name "*.lock" -delete
+
+script:
+  - sbt ++$TRAVIS_SCALA_VERSION ciBuild

CONTRIBUTING.md

@@ -21,7 +21,9 @@ To compile and run tests: `sbt test`.
 
 ## Performing a release (for project maintainers)
 
-TODO
+1. Run `docker login --username=<username>` and when prompted add the password for your Docker Hub account. Note that you need to be a member of the `skyuk` Docker Hub organization.
+2. Run `sbt ciRelease` to perform the release of the Docker artifact to Docker Hub.
+3. The Docker Image will be immediately live and therefore will need to be deleted if there has been a problem.
 
 ## Contributor Code of Conduct
 

README.md

@@ -15,24 +15,24 @@ use it as input, output and data store.
 
 ## How it works
 
-The Kafka Message Scheduler (KMS, for short) consumes messages from a source
-topic. The keys are Schedule IDs, and the values Schedule messages in Avro
-format.
+The Kafka Message Scheduler (KMS, for short) consumes messages from a source topic.  On this topic:
+-  message keys are "Schedule IDs" - string values, with an expectation of uniqueness
+-  message values are Schedule messages, encoded in Avro binary format according to the [Schema](#schema).
 
 A schedule is composed of:
 - The topic you want to send the delayed message to
 - The timestamp telling when you want that message to be delivered
 - The actual message to be sent, both key and value
 
-The KMS will be responsible of sending the actual message to the specified
-topic when the time comes.
+The KMS is responsible for sending the actual message to the specified topic at the specified time.
 
-The Schedule ID can be used to delete a scheduled message, via a delete
-message (with a null value) in the source topic.
+The Schedule ID can be used to delete a scheduled message, via a delete message (with a null message value)
+in the source topic.
 
-## Schema generation
+## Schema
 
-To generate the avro schema from the Schedule case class, run `sbt schema`. The schema will appear in `avro/target/schemas/schedule.avsc`
+To generate the avro schema from the Schedule case class, run `sbt schema`. The schema will be written to
+`avro/target/schemas/schedule.avsc`.
 
 ## How to run it
 
@@ -44,14 +44,12 @@ Start Kafka:
 
 Start KMS:
 
-`docker run --net=host --add-host moby:127.0.0.1 -e SCHEDULE_TOPIC=scheduler skyuk/scheduler`
-
+`docker run --net=host --add-host moby:127.0.0.1 -e SCHEDULE_TOPIC=scheduler skyuk/kafka-message-scheduler`
 
 ### Send messages
 
-With the services running, you can send a message to `scheduler` topic. See [Schema generation](#schema-generation)
-for generating the Avro schema.
-
+With the services running, you can send a message to the defined scheduler topic (`scheduler` in the example
+above). See the [Schema](#schema) section for details of generating the Avro schema to be used.
 
 ### Monitoring
 
@@ -60,7 +58,7 @@ JMX metrics are exposed using Kamon. Port 9186 has to be exposed to obtain them.
 ### Topic configuration
 
 The `schedule-topic` must be configured to use [log compaction](https://kafka.apache.org/documentation/#compaction). 
-This is to allow the scheduler to delete the schedule after it has been written to its destination topic. This is very 
-important because the scheduler uses the `schedule-topic` to reconstruct its state. This application will also support 
-longer-term schedules so log compaction is required to ensure they are not prematurely removed from Kafka allowing the 
-application to recover them after a restart.
+This is for two reasons:
+1.  to allow the scheduler to delete the schedule after it has been written to its destination topic.
+2.  because the scheduler uses the `schedule-topic` to reconstruct its state - in case of a restart of the
+    KMS, this ensures that schedules are not lost.

build.sbt

@@ -1,4 +1,6 @@
 import com.typesafe.sbt.packager.docker.Cmd
+import Aliases._
+import Release._
 
 val kafkaVersion = "0.10.2.1" // TODO: move to 0.11.0.0 when akka-stream-kafka upgrades
 val akkaVersion = "2.5.3"
@@ -42,7 +44,7 @@ val commonSettings = Seq(
 val jmxPort = 9186
 
 val dockerSettings = Seq(
-  packageName in Docker := packageName.value,
+  packageName in Docker := "kafka-message-scheduler",
   dockerBaseImage := "openjdk:8u131-jre-alpine",
   dockerRepository := Some("skyuk"),
   maintainer in Docker := "Sky",
@@ -68,10 +70,11 @@ val jmxSettings = Seq(
 ).mkString(" ")
 
 lazy val scheduler = (project in file("scheduler"))
-  .enablePlugins(BuildInfoPlugin, JavaAppPackaging, UniversalDeployPlugin, JavaAgent)
+  .enablePlugins(BuildInfoPlugin, JavaAppPackaging, UniversalDeployPlugin, JavaAgent, DockerPlugin)
   .settings(commonSettings)
   .settings(
     libraryDependencies ++= dependencies,
+    dependencyOverrides += "org.scalacheck" %% "scalacheck" % "1.13.5",
     resolvers += Resolver.bintrayRepo("cakesolutions", "maven"),
     addCompilerPlugin("org.scalamacros" % "paradise" % "2.1.0" cross CrossVersion.full),
     scalacOptions ++= Seq(
@@ -86,17 +89,19 @@ lazy val scheduler = (project in file("scheduler"))
     javaOptions in Universal += jmxSettings,
     buildInfoSettings,
     dockerSettings,
-    dependencyOverrides += "org.scalacheck" %% "scalacheck" % "1.13.5"
-  ).enablePlugins(DockerPlugin)
+    releaseSettings
+  )
 
 val schema = inputKey[Unit]("Generate the Avro schema file for the Schedule schema.")
 
 lazy val avro = (project in file("avro"))
   .settings(commonSettings)
   .settings(schema := (run in Compile).toTask("").value)
   .dependsOn(scheduler % "compile->compile")
+  .disablePlugins(ReleasePlugin)
 
 lazy val root = (project in file("."))
   .settings(commonSettings)
+  .settings(defineCommandAliases)
   .aggregate(scheduler, avro)
-  .disablePlugins(DockerPlugin)
+  .disablePlugins(ReleasePlugin)

project/Aliases.scala

@@ -0,0 +1,9 @@
+import sbt._
+
+object Aliases {
+
+  lazy val defineCommandAliases = {
+    addCommandAlias("ciBuild", ";clean; test; schema") ++
+      addCommandAlias("ciRelease", ";clean; schema; project scheduler; release with-defaults")
+  }
+}

project/Release.scala

@@ -0,0 +1,36 @@
+import com.typesafe.sbt.packager.docker.DockerPlugin.autoImport.{Docker => docker}
+import com.typesafe.sbt.packager.universal.UniversalPlugin.autoImport.Universal
+import sbt.Keys._
+import sbt.taskKey
+import sbtrelease.ReleasePlugin.autoImport._
+import sbtrelease.ReleaseStateTransformations._
+import sbtrelease._
+
+object Release {
+  // Useful tasks to show what versions would be used if a release was performed.
+  private val showReleaseVersion = taskKey[String]("the future version once releaseNextVersion has been applied to it")
+  private val showNextVersion = taskKey[String]("the future version once releaseNextVersion has been applied to it")
+
+  lazy val releaseSettings = Seq(
+    releaseUseGlobalVersion := false,
+    releaseVersionBump := sbtrelease.Version.Bump.Minor,
+    releaseTagName := s"${name.value}-${version.value}",
+    releaseTagComment := s"Releasing ${version.value} of module: ${name.value}",
+    releasePublishArtifactsAction:= (publish in Universal).value,
+    releaseProcess := Seq[ReleaseStep](
+      checkSnapshotDependencies,
+      releaseStepCommand(ExtraReleaseCommands.initialVcsChecksCommand),
+      inquireVersions,
+      setReleaseVersion,
+      runTest,
+      commitReleaseVersion,
+      tagRelease,
+      ReleaseStep(releaseStepTask(publish in docker)),
+      setNextVersion,
+      commitNextVersion,
+      pushChanges
+    ),
+    showReleaseVersion := { val rV = releaseVersion.value.apply(version.value); println(rV); rV },
+    showNextVersion := { val nV = releaseNextVersion.value.apply(version.value); println(nV); nV }
+  )
+}

project/plugins.sbt

@@ -1 +1,4 @@
-addSbtPlugin("com.typesafe.sbt" % "sbt-native-packager" % "1.2.0")
+addSbtPlugin("com.eed3si9n" % "sbt-buildinfo" % "0.7.0")
+addSbtPlugin("com.github.gseitz" % "sbt-release" % "1.0.6")
+addSbtPlugin("com.lightbend.sbt" % "sbt-javaagent" % "0.1.4")
+addSbtPlugin("com.typesafe.sbt" % "sbt-native-packager" % "1.2.1")

scheduler/src/main/scala/com/sky/kms/SchedulerApp.scala

@@ -1,5 +1,6 @@
 package com.sky.kms
 
+import com.sky.BuildInfo
 import com.sky.kms.config.AppConfig
 import com.sky.kms.streams.ScheduleReader
 import com.typesafe.scalalogging.LazyLogging
@@ -14,7 +15,7 @@ object SchedulerApp extends App with LazyLogging with AkkaComponents {
   val conf = loadConfigOrThrow[AppConfig]
   Kamon.start()
 
-  logger.info("Kafka Message Scheduler starting up...")
+  logger.info(s"Kafka Message Scheduler ${BuildInfo.name} ${BuildInfo.version} starting up...")
   val app = ScheduleReader.reader.run(conf)
 
   sys.addShutdownHook {

scheduler/version.sbt

@@ -0,0 +1 @@
+version := "0.1.0-SNAPSHOT"