chore: refactors using resource and other improvements

sonar-project.properties

@@ -10,3 +10,5 @@ sonar.sourceEncoding=UTF-8
 sonar.java.binaries=target/scala-2.13
 sonar.java.test.binaries=target/scala-2.13
 sonar.scala.coverage.reportPaths=target/scala-2.13/scoverage-report/scoverage.xml
+sonar.coverage.exclusions=**/Main.scala
+sonar.exclusions=**/Main.scala

src/main/scala/com/example/Main.scala

@@ -1,25 +1,23 @@
 package com.example
 
-import cats.effect.{ExitCode, IO, IOApp}
-import com.example.global.infrastructure.slick.Fly4sMigrations
-import com.typesafe.scalalogging.StrictLogging
+import cats.effect.{IO, Resource, ResourceApp}
+import com.example.global.infrastructure.slick.Fly4sModule
 
-object Main extends IOApp with StrictLogging {
+object Main extends ResourceApp.Forever {
 
-  override def run(args: List[String]): IO[ExitCode] = {
-    val module = MainModule.initialize
-
-    val migrateDb = Fly4sMigrations.migrateDb(module.dbConfig).use(_ => IO.unit)
-
-    val startHttpApi = module.httpApi.resource
-      .use { _ =>
-        val baseUrl = module.httpConfig.toUrl("http://")
-        logger.info(s"Documentation from $baseUrl/docs")
-        logger.info(s"Metrics from $baseUrl/metrics")
-        IO.never
-      }
-
-    migrateDb *> startHttpApi.as(ExitCode.Success)
-  }
+  /** Creating a resource that will be used to run the application composed of three steps:
+    *
+    *   - the first creates the main module (which loads the configuration and initializes the prometheus metrics)
+    *   - the second migrates the database if needed (it will create the new migration file if it don't exist)
+    *   - the third allocates the http api resource (which starts the http server and exposes the endpoints)
+    *
+    * ResourceApp.Forever uses the last resource through a process without termination (so the http server will be
+    * available while our application is running).
+    */
+  override def run(args: List[String]): Resource[IO, Unit] = for {
+    module <- MainModule.resource
+    _      <- Fly4sModule.migrateDbResource
+    _      <- module.httpApi.resource
+  } yield ()
 
 }

src/main/scala/com/example/MainModule.scala

@@ -1,27 +1,30 @@
 package com.example
 
+import cats.effect.{IO, Resource}
 import com.example.books.BookModule
 import com.example.global.infrastructure.http._
-import com.example.shared.infrastructure.config.Config
+import com.example.shared.infrastructure.config.ConfigModule
 import com.softwaremill.macwire._
+import io.prometheus.client.hotspot
+
+/** To Initialised resources needed by the application to start.
+  */
+trait MainModule extends ConfigModule with BookModule {
+  def initialize(): MainModule = {
+    loadConfig()
+    hotspot.DefaultExports.initialize()
+    this
+  }
 
-trait MainModule extends BookModule {
-
-  def config: Config
-
-  lazy val dbConfig: DBConfig     = DBConfig(config.db.driver, config.db.url, config.db.user, config.db.password)
-  lazy val httpConfig: HttpConfig = HttpConfig(config.api.host, config.api.port)
+  lazy val dbConfig: DBConfig    = config.db
+  lazy val apiConfig: HttpConfig = config.api
 
   lazy val metricsApi: MetricsApi = wire[MetricsApi]
   lazy val httpApi: HttpApi       = wire[HttpApi]
 }
 
 object MainModule {
+  lazy val initialize: MainModule = new MainModule {}.initialize()
 
-  def initialize: MainModule = {
-    val initModule = new InitModule {}
-    initModule.initialize()
-    new MainModule { override def config: Config = initModule.config }
-  }
-
+  val resource: Resource[IO, MainModule] = Resource.make(IO(initialize))(_ => IO.unit)
 }

src/main/scala/com/example/global/infrastructure/http/DBConfig.scala

@@ -1,8 +1,10 @@
 package com.example.global.infrastructure.http
 
+import com.example.shared.infrastructure.config.Sensitive
+
 case class DBConfig(
     driver: String,
     url: String,
     user: String,
-    password: String
+    password: Sensitive
 )

src/main/scala/com/example/global/infrastructure/slick/Fly4sModule.scala

@@ -0,0 +1,46 @@
+package com.example.global.infrastructure.slick
+
+import cats.effect._
+import cats.implicits._
+import com.example.books.infrastructure.slick.BookMapping
+import com.example.shared.infrastructure.slick.HasSlickPgProvider
+import fly4s.core.Fly4s
+import fly4s.core.data._
+
+import java.io.{File, PrintWriter}
+import java.nio.file.{Files, Paths}
+
+object Fly4sModule extends HasSlickPgProvider with BookMapping {
+
+  private val migrationsFolder = "src/main/resources/db/migration"
+
+  import profile.api._
+  private val schemas = Books.schema // add more schemas on demand using ++ operator
+
+  private val migrationFile = migrationsFolder + "/V003__create_books_table.sql" // change name on demand
+
+  private val witterAssistant = Resource.make {
+    for {
+      folder <- IO(new File(migrationsFolder))
+      _      <- IO.unlessA(folder.exists())(IO(folder.mkdirs()).void)
+
+      _ <- IO.unlessA(Files.exists(Paths.get(migrationFile))) {
+             IO {
+               val w = new PrintWriter(migrationFile)
+               w.write(schemas.createStatements.mkString("\n"))
+               w.close()
+             }
+           }
+    } yield ()
+  }(_ => IO.unit)
+
+  private lazy val fly4sConfig = Fly4s.make[IO](
+    url = dbConfig.url,
+    user = dbConfig.user.some,
+    password = dbConfig.password.value.toCharArray.some,
+    config = Fly4sConfig(baselineOnMigrate = true)
+  )
+
+  def migrateDbResource: Resource[IO, MigrateResult] = witterAssistant *> fly4sConfig.evalMap(_.migrate)
+
+}

src/main/scala/com/example/shared/infrastructure/config/ConfigModule.scala

@@ -12,7 +12,7 @@ trait ConfigModule extends StrictLogging {
 
   def loadConfig(): Unit = {
     val info = s"""
-                   |Configuration:
+                   |Load Configuration:
                    |-----------------------
                    |API: ${config.api}
                    |DB: ${config.db}

src/main/scala/com/example/shared/infrastructure/config/Sensitive.scala

@@ -1,5 +1,5 @@
 package com.example.shared.infrastructure.config
 
-case class Sensitive(value: String) extends AnyVal {
+final case class Sensitive(value: String) extends AnyVal {
   override def toString: String = "***"
 }

src/main/scala/com/example/shared/infrastructure/slick/HasSlickPgProvider.scala

@@ -8,9 +8,7 @@ import slick.jdbc.{ResultSetConcurrency, ResultSetType}
 
 import scala.concurrent.ExecutionContext.Implicits.global
 
-trait HasSlickPgProvider {
-
-  private val dbConfig = MainModule.initialize.dbConfig
+trait HasSlickPgProvider extends MainModule {
 
   val profile: PgProfile = PgProfile
 
@@ -19,7 +17,7 @@ trait HasSlickPgProvider {
   val db: Database = Database.forURL(
     url = dbConfig.url,
     user = dbConfig.user,
-    password = dbConfig.password,
+    password = dbConfig.password.value,
     driver = dbConfig.driver
   )
 

src/test/scala/com/example/books/infrastructure/http/BookApiTest.scala

@@ -85,6 +85,10 @@ class BookApiTest extends HasHttp4sRoutesSuite with BookCodecs with AuthorHelper
     )
   }
 
+  test(GET(uri"books?sort=isbn,year")).alias("LIST WITH SORT (isbn and year)") { response =>
+    assertEquals(response.status, Status.Ok)
+  }
+
   test(GET(uri"books?sort=year")).alias("LIST WITH SORT (year)") { response =>
     assertEquals(response.status, Status.Ok)
     assertIO(

src/test/scala/com/example/shared/infrastructure/http/HasHttp4sRoutesSuite.scala

@@ -2,10 +2,10 @@ package com.example.shared.infrastructure.http
 
 import cats.effect.IO
 import com.example.MainModule
-import com.example.global.infrastructure.slick.Fly4sMigrations
+import com.example.global.infrastructure.slick.Fly4sModule
 
 trait HasHttp4sRoutesSuite extends munit.Http4sHttpRoutesSuite {
   lazy val module: MainModule = MainModule.initialize
 
-  Fly4sMigrations.migrateDb(module.dbConfig).use(_ => IO.unit).unsafeRunSync()
+  Fly4sModule.migrateDbResource.use(_ => IO.unit).unsafeRunSync()
 }