Java component template using Gradle, the Gradle Kotlin DSL, and the Gradle wrapper

.gitignore

@@ -1,4 +1,5 @@
 .idea/
 **.DS_STORE
 **.DS_Store
-*.iml
+*.iml
+.gradle

templates/java-gradlew-kts/HelloWorld/.gitignore

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+*build/
+build
+.idea/
+**.DS_STORE
+**.DS_Store
+*.iml
+target/

templates/java-gradlew-kts/HelloWorld/README.md

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+## My Project
+
+TODO: Fill this README out!
+
+Be sure to:
+
+* Change the title in this README
+* Edit your repository description 
+
+## License
+
+Add License information here
+

templates/java-gradlew-kts/HelloWorld/build.gradle.kts

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+import kotlinx.serialization.json.Json.Default.parseToJsonElement
+import kotlinx.serialization.json.JsonObject
+import kotlinx.serialization.json.JsonPrimitive
+import org.apache.tools.ant.taskdefs.condition.Os
+import org.gradle.internal.Try
+
+buildscript {
+    dependencies {
+        // This is so we can parse the gdk-config.json file and get the version, author, bucket, and region information
+        classpath("org.jetbrains.kotlinx:kotlinx-serialization-json-jvm:1.3.2")
+    }
+}
+
+plugins {
+    kotlin("jvm") version "1.6.10"
+    id("application")
+    id("java")
+    id("idea")
+
+    // This creates the fat JAR
+    id("com.github.johnrengelman.shadow") version "7.1.2"
+}
+
+group = "com.hello"
+description = "HelloWorld"
+
+application.mainClass.set("com.hello.App")
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testImplementation("org.junit.jupiter:junit-jupiter-api:5.5.2")
+    testImplementation("org.junit.jupiter:junit-jupiter-engine:5.5.2")
+}
+
+// NOTE: Version number is pulled from gdk-config.json. Change this value to override.
+val componentVersionOverride: String? = null
+
+// Set this value to true if you want to be able to use the NEXT_PATCH value in gdk-config.json.
+// If this is false and gdk-config.json contains a NEXT_PATCH value, the build will fail.
+// Generally during development this should be set to true. When committing a release, this should be set to false.
+val allowVersionPlaceholder = true
+
+// This is the version number used in the JAR name when building with the NEXT_PATCH version value.
+// If NEXT_PATCH is set and allowVersionPlaceholder is true the JAR will be called ${project.description}-NEXT_PATCH.jar
+// This is done so gdk can find the correct JAR after a build.
+val nextPatchTempVersionNumber = "1.0.0"
+
+tasks.shadowJar {
+    // Get either the specified component version, NEXT_PATCH, or the default version
+    val componentVersion = componentVersionOverride ?: getComponentVersion()
+    archiveFileName.set("${project.description}-$componentVersion.jar")
+}
+
+tasks.register<Exec>("publish") {
+    description = "Build the component, if necessary, and publish it as a Greengrass component"
+    // gdk component publish doesn't always do a build but this task does
+    dependsOn("build")
+
+    doFirst {
+        // Check to make sure that all the values are filled in. If they aren't will let the user know what to do.
+        checkForPlaceholders()
+    }
+
+    workingDir = file(".")
+
+    // Finally, we'll call gdk component publish to do the real work of publishing the component for us
+    commandLine = if (Os.isFamily(Os.FAMILY_WINDOWS)) listOf("cmd", "/c") else listOf("/bin/bash", "-c")
+    commandLine = commandLine + listOf("$gdk component publish")
+}
+
+val configFile = "gdk-config.json"
+val versionPlaceholder = "NEXT_PATCH"
+val authorPlaceholder = "<PLACEHOLDER_AUTHOR>"
+val bucketPlaceholder = "<PLACEHOLDER_BUCKET>"
+val regionPlaceholder = "<PLACEHOLDER_REGION>"
+val gdkCliConfigurationFileDocsUrl =
+    "https://docs.aws.amazon.com/greengrass/v2/developerguide/gdk-cli-configuration-file.html"
+
+fun getTopLevelComponent(): JsonObject {
+    // Reference the gdk-config.json file
+    return Try.ofFailable { file(configFile) }
+        // Get the entire file as text
+        .tryMap { it.readText() }
+        // Parse the text as JSON as a JSON object
+        .tryMap { parseToJsonElement(it) as JsonObject }
+        // Get the top level component element as a JSON object
+        .tryMap { it["component"] as JsonObject }
+        // Fail here if anything above went wrong
+        .mapFailure { throw IllegalStateException("Failed to parse $configFile [${it.message}]") }
+        // If we get here everything was successful, and we can unwrap the Try
+        .get()
+}
+
+fun getComponent(): JsonObject {
+    val topLevelComponent = getTopLevelComponent()
+
+    // Sanity check to make sure we are working with a file that is set up as we expected
+    if (topLevelComponent.keys.size > 1) throw IllegalStateException("Found more than one component in $configFile")
+    if (topLevelComponent.keys.isEmpty()) throw IllegalStateException("Did not find any components in $configFile")
+
+    // The only key should be the component name
+    val componentName = topLevelComponent.keys.first()
+
+    // Get the user specified component element as a JsonObject
+    return Try.ofFailable { topLevelComponent[componentName] as JsonObject }
+        // Fail here if anything above went wrong
+        .mapFailure { throw IllegalStateException("Failed process the component information [${it.message}] in $configFile") }
+        // If we get here everything was successful, and we can unwrap the Try
+        .get()
+}
+
+fun getComponentVersion(): String {
+    val component = getComponent()
+
+    // Get the version element as a JSON primitive
+    val componentVersion = Try.ofFailable { component["version"] as JsonPrimitive }
+        // Extract the string from the primitive object
+        .tryMap { it.content }
+        // Fail here if anything above went wrong
+        .mapFailure { throw IllegalStateException("Component version could not be found in $configFile. This needs to be set to build the component.") }
+        // If we get here everything was successful, and we can unwrap the Try
+        .get()
+
+    // If the version is NEXT_PATCH, and we're allowing the placeholder then set the version to the temp version number (usually "1.0.0")
+    //   otherwise just use the value they specified
+    if (allowVersionPlaceholder) return if (componentVersion == versionPlaceholder) nextPatchTempVersionNumber else componentVersion
+
+    // At this point the NEXT_PATCH version is NOT allowed
+
+    // If the version isn't NEXT_PATCH just return it
+    if (versionPlaceholder != componentVersion) return componentVersion
+
+    // Throw an exception if the version is NEXT_PATCH since it's not allowed here
+    throw IllegalStateException("Component version is still set to $versionPlaceholder in $configFile. This needs to be updated to build the component or allowVersionPlaceholder needs to be set to true in build.gradle.kts.")
+}
+
+val documentationMessage = "See $gdkCliConfigurationFileDocsUrl for information on how to configure this."
+
+fun checkForPlaceholders() {
+    val publish = getPublishJsonObjectOrThrow()
+
+    val authorIsPlaceholder = isElementPlaceholder(getComponent(), "author", authorPlaceholder)
+    val bucketIsPlaceholder = isElementPlaceholder(publish, "bucket", bucketPlaceholder)
+    val regionIsPlaceholder = isElementPlaceholder(publish, "region", regionPlaceholder)
+
+    var errors = emptyList<String>()
+
+    if (authorIsPlaceholder) errors = errors + "Author information is still set to $authorPlaceholder in $configFile."
+    if (bucketIsPlaceholder) errors = errors + "Bucket information is still set to $bucketPlaceholder in $configFile."
+    if (regionIsPlaceholder) errors = errors + "Region information is still set to $regionPlaceholder in $configFile."
+
+    if (errors.isNotEmpty()) {
+        // If there were any errors gather them with the documentation link and throw an exception
+        errors = errors + documentationMessage
+        throw IllegalStateException(errors.joinToString("\n"))
+    }
+}
+
+fun isElementPlaceholder(
+    jsonObject: JsonObject,
+    elementName: String,
+    placeholder: String
+): Boolean {
+    return Try.ofFailable { jsonObject }
+        // Get the element by name as a JSON primitive
+        .tryMap { it[elementName] as JsonPrimitive }
+        // Extract the string from the primitive object
+        .tryMap { it.content }
+        // Determine if it is the placeholder value
+        .tryMap { placeholder == it }
+        // Fail here if anything above went wrong
+        .mapFailure { throw IllegalStateException("The value for $elementName in $configFile is not set. $documentationMessage") }
+        // If we get here everything was successful, and we can unwrap the Try
+        .get()
+}
+
+fun getPublishJsonObjectOrThrow(): JsonObject {
+    return Try.ofFailable { getComponent() }
+        // Get the publish elements as a JSON object
+        .tryMap { it["publish"] as JsonObject }
+        // Fail here if anything above went wrong
+        .mapFailure { throw IllegalStateException("Failed to parse publish information in $configFile [${it.message}]. $documentationMessage") }
+        // If we get here everything was successful, and we can unwrap the Try
+        .get()
+}
+
+// This can be changed to use gdk in different locations when needed for gdk debugging
+val gdk = "gdk"

templates/java-gradlew-kts/HelloWorld/gdk-config.json

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+{
+  "component": {
+    "com.example.JavaHelloWorld": {
+      "author": "<PLACEHOLDER_AUTHOR>",
+      "version": "NEXT_PATCH",
+      "build": {
+        "build_system": "gradlew"
+      },
+      "publish": {
+        "bucket": "<PLACEHOLDER_BUCKET>",
+        "region": "<PLACEHOLDER_REGION>"
+      }
+    }
+  },
+  "gdk_version": "1.0.0"
+}

templates/java-gradlew-kts/HelloWorld/gradle/wrapper/gradle-wrapper.properties

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+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.4-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists