Building Gradle Plugins

Presented at Chicago Roboto on April 21st, 2017

Transcript

1. Building Gradle Plugins @bryansills
2. What Is Gradle? It’s a build system. More specifically, it’s the main supported build system for building Android apps.
3. What Are Gradle Plugins? Small chunks of code that can: • Automate simple parts of your build process • Provide the framework to use outside tools in your build • Extract useful information about the build process
4. No, seriously, what is a Gradle plugin?
5. Crashlytics
6. buildscript { repositories { maven { url 'https://maven.fabric.io/public' } } dependencies { classpath 'io.fabric.tools:gradle:1.+' } } apply plugin: 'com.android.application' apply plugin: 'io.fabric' repositories { maven { url 'https://maven.fabric.io/public' } } dependencies { compile 'com.android.support:appcompat-v7:25.3.1' compile 'com.android.support.constraint:constraint-layout:1.0.2' compile('com.crashlytics.sdk.android:crashlytics:2.6.7@aar') { transitive = true; } } {... more gradle stuff ...} app/build.gradle
7. Crashlytics Tasks $ ./gradlew assembleDebug crashlyticsUploadDistributionDebug {...} :app:prepareDebugDependencies :app:compileDebugAidl UP-TO-DATE :app:compileDebugRenderscript UP-TO-DATE :app:generateDebugBuildConfig UP-TO-DATE :app:mergeDebugShaders UP-TO-DATE :app:compileDebugShaders UP-TO-DATE :app:generateDebugAssets UP-TO-DATE :app:mergeDebugAssets UP-TO-DATE :app:processDebugManifest UP-TO-DATE :app:fabricGenerateResourcesDebug :app:generateDebugResValues UP-TO-DATE :app:generateDebugResources :app:mergeDebugResources :app:processDebugResources :app:generateDebugSources :app:incrementalDebugJavaCompilationSafeguard UP-TO-DATE :app:javaPreCompileDebug :app:compileDebugJavaWithJavac UP-TO-DATE :app:compileDebugNdk UP-TO-DATE :app:compileDebugSources UP-TO-DATE :app:transformClassesWithDexForDebug UP-TO-DATE :app:mergeDebugJniLibFolders UP-TO-DATE :app:transformNativeLibsWithMergeJniLibsForDebug UP-TO-DATE :app:processDebugJavaRes UP-TO-DATE :app:transformResourcesWithMergeJavaResForDebug UP-TO-DATE :app:validateSigningDebug :app:packageDebug :app:assembleDebug :app:crashlyticsUploadDistributionDebug BUILD SUCCESSFUL Total time: 13.37 secs
8. :crashlyticsUploadDistribution<VARIANT> • Uploads your .apk (and other fun stuff) to Crashlytics Beta • <VARIANT> refers to Android’s build variant ◦ Defaults to “Debug” and “Release” • Standalone task
9. :fabricGenerateResources<VARIANT> • Generates a unique identifier for your build into an XML file • Inserted into the middle of the build process
10. What prompted you to learn about Gradle plugins, Bryan? I wanted to see if some JSON files were actually valid JSON.
11. Context (Not that Context) • My client’s project uses JSON files to define the configuration of the app ◦ Cross-platform between iOS and Android • Some of the configurable elements: ◦ Server endpoints (and other various networking pieces) ◦ UI Elements (Individual layouts, Drawer items, colors) ◦ Core features (User signup) • These JSON files come from third-party teams • The people who make these JSON files may not be in technical roles
12. So what happens... • Build the app • Install on my device • Open the app on my phone • Go a few screens to switch JSON configurations FORCE CLOSE...
13. Still… this seems like a lot of work... Why don’t you just use an online JSON formatter? • These JSON files change often • We deal with third-party developers in our codebase • These are dumb, painful mistakes that can be prevented
14. Why Use Gradle Plugins? Bash still kinda works… • Write in Java, Kotlin, or Groovy • You will always have Gradle when building your Android app • Use all the Java libraries and tools in your plugin • Build on top of other Gradle plugins • Integrate into your build
15. Project Structure There are 3 ways to build your plugin: • Directly in the build.gradle file • In the root buildSrc/ folder of your project • In a standalone project
16. Setting up the plugin’s build.gradle plugins { id "java-gradle-plugin" } group "ninja.bryansills" version '0.0.1' gradlePlugin { plugins { jsonVerify { id = "ninja.bryansills.gradle-json-verify" implementationClass = "ninja.bryansills.JsonVerifyPlugin" } } }
17. plugins { id "java-gradle-plugin" } group "ninja.bryansills" version '0.0.1' gradlePlugin { plugins { jsonVerify { id = "ninja.bryansills.gradle-json-verify" implementationClass = "ninja.bryansills.JsonVerifyPlugin" } } } Setting up the plugin’s build.gradle
18. Consuming this Plugin buildscript { dependencies { classpath "ninja.bryansills:gradle-json-verify:0.0.1" } } apply plugin: 'ninja.bryansills.gradle-json-verify'
19. Create your initial Java Plugin file package ninja.bryansills; import org.gradle.api.Plugin; import org.gradle.api.Project; public class JsonVerifyPlugin implements Plugin<Project> { @Override public void apply(Project project) { } }
20. Project Setup settings.gradle rootProject.name = 'gradle-json-verify-project' include ':consumer', ':gradle-json-verify'
21. Why isn’t this working? $ ./gradlew :consumer:dependencies FAILURE: Build failed with an exception. * What went wrong: A problem occurred configuring project ':consumer'. > Could not resolve all dependencies for configuration ':consumer:classpath'. > Could not find ninja.bryansills:gradle-json-verify:0.0.1. Searched in the following locations: https://jcenter.bintray.com/ninja/bryansills/gradle-json-verify/0.0.1/gradle-json-verify-0.0.1.pom https://jcenter.bintray.com/ninja/bryansills/gradle-json-verify/0.0.1/gradle-json-verify-0.0.1.jar Required by: project :consumer * Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. BUILD FAILED Total time: 2.826 secs
22. Gradle Lifecycle • There are 3 phases to the Gradle lifecycle: ◦ Initialization ◦ Configuration ◦ Execution • All projects need to configured before they are executed… • But the consumer needs a compiled plugin… • So...
23. The :uploadArchives task • Allows you to build the plugin and upload the .jar to a local or remote repository • Solves the configuration phase issue • A little tedious while doing iterative development on the plugin ◦ Ughhhhhhhhhhhhh 2 different commands
24. Composite Builds settings.gradle rootProject.name = 'gradle-json-verify-project' include ':consumer', ':gradle-json-verify' includeBuild './gradle-json-verify' • Fairly new feature in Gradle (Added in late 2016) • A composite build is simply a build that includes other builds • Allows the plugin to be fully built before the consumer needs it
25. Composite Builds $ ./gradlew :consumer:dependencies [composite-build] Configuring build: /Users/bsills/android/gradle-json-verify :gradle-json-verify:compileJava UP-TO-DATE :gradle-json-verify:pluginDescriptors UP-TO-DATE :gradle-json-verify:processResources UP-TO-DATE :gradle-json-verify:classes UP-TO-DATE :gradle-json-verify:jar UP-TO-DATE :consumer:dependencies {...} BUILD SUCCESSFUL Total time: 1.538 secs
26. Creating a Custom Task public class JsonVerifyPlugin implements Plugin<Project> { @Override public void apply(Project project) { Task jsonVerifyTask = project.getTasks().create("jsonVerify", JsonVerifyTask.class); } } public class JsonVerifyTask extends DefaultTask { @TaskAction public void jsonVerify() { System.out.println("We are verifying JSON"); } }
27. Creating a Custom Task $ ./gradlew :consumer:jsonVerify [composite-build] Configuring build: /Users/bsills/android/gradle-json-verify :gradle-json-verify:compileJava UP-TO-DATE :gradle-json-verify:pluginDescriptors UP-TO-DATE :gradle-json-verify:processResources UP-TO-DATE :gradle-json-verify:classes UP-TO-DATE :gradle-json-verify:jar UP-TO-DATE :consumer:jsonVerify We are verifying JSON BUILD SUCCESSFUL Total time: 1.021 secs
28. Depending On Other Tasks $ ./gradlew :consumer:assembleDebug [composite-build] Configuring build: /Users/bsills/android/gradle-json-verify :gradle-json-verify:compileJava :gradle-json-verify:pluginDescriptors UP-TO-DATE :gradle-json-verify:processResources UP-TO-DATE :gradle-json-verify:classes :gradle-json-verify:jar :consumer:preBuild :consumer:preDebugBuild :consumer:checkDebugManifest :consumer:preReleaseBuild {... continued ...}
29. Depending On Other Tasks public class JsonVerifyPlugin implements Plugin<Project> { @Override public void apply(Project project) { Task jsonVerifyTask = project.getTasks().create("jsonVerify", JsonVerifyTask.class); Set<Task> tasks = project.getTasksByName("preBuild", true); tasks.forEach(task -> task.dependsOn(jsonVerifyTask)); } }
30. Depending On Other Tasks $ ./gradlew :consumer:assembleDebug [composite-build] Configuring build: /Users/bsills/android/gradle-json-verify :gradle-json-verify:compileJava :gradle-json-verify:pluginDescriptors UP-TO-DATE :gradle-json-verify:processResources UP-TO-DATE :gradle-json-verify:classes :gradle-json-verify:jar :consumer:jsonVerify We are verifying JSON :consumer:preBuild :consumer:preDebugBuild :consumer:checkDebugManifest :consumer:preReleaseBuild {... continued ...}
31. Taking Input JsonVerifyTask.java @TaskAction public void jsonVerify() { ConfigurableFileTree configFiles = getProject().fileTree(getProject().getProjectDir() + "/json/"); configFiles.forEach(file -> { if (".json".equals(getFileExtension(file))) { verifyJsonFile(file); } }); } {... continued ...}
32. Verifying Input JsonVerifyTask.java private void verifyJsonFile(File file) { Moshi moshi = new Moshi.Builder().build(); JsonAdapter<Map> jsonAdapter = moshi.adapter(Map.class); try { Map jsonMap = jsonAdapter.fromJson(Okio.buffer(Okio.source(file))); } catch (Exception exception) { throw new JsonVerifyException(file.getName(), exception); } }
33. Taking Input consumer/json/sample.json { "id": 1, "name": "A green door", "price": 12.50, "tags": ["home", "green"], } $ ./gradlew :consumer:preBuild [composite-build] Configuring build: /Users/bsills/android/backup/gradle-json-verify :gradle-json-verify:compileJava :gradle-json-verify:pluginDescriptors UP-TO-DATE :gradle-json-verify:processResources UP-TO-DATE :gradle-json-verify:classes :gradle-json-verify:jar :consumer:jsonVerify FAILED FAILURE: Build failed with an exception. * What went wrong: Execution failed for task ':consumer:jsonVerify'. > Expected name at path $.tags in file: sample.json * Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. BUILD FAILED Total time: 1.129 secs
34. Taking Input JsonVerifyTask.java @TaskAction public void jsonVerify() { ConfigurableFileTree configFiles = getProject().fileTree(getProject().getProjectDir() + "/json/"); configFiles.forEach(file -> { if (".json".equals(getFileExtension(file))) { verifyJsonFile(file); } }); } {... continued ...}
35. Plugin Extensions consumer/build.gradle {...} apply plugin: 'ninja.bryansills.gradle-json-verify' jsonVerify { srcDir = "whatever/you/want/" } package ninja.bryansills; public class JsonVerifyExtension { String srcDir = "/json/"; public String getSrcDir() { return srcDir; } public void setSrcDir(String srcDir) { this.srcDir = srcDir; } }
36. Plugin Extensions public class JsonVerifyPlugin implements Plugin<Project> { @Override public void apply(Project project) { project.getExtensions().create("jsonVerify", JsonVerifyExtension.class); Task jsonVerifyTask = project.getTasks().create("jsonVerify", JsonVerifyTask.class); {... continued ...} public class JsonVerifyTask extends DefaultTask { @TaskAction public void jsonVerify() { JsonVerifyExtension extension = (JsonVerifyExtension) getProject().getExtensions().findByName("jsonVerify"); ConfigurableFileTree configFiles = getProject().fileTree(getProject().getProjectDir() + "/" + extension.getSrcDir()); {... continued ...}
37. Incremental Builds @Input @InputFile @InputFiles @InputDirectory @Output @OutputFile @OutputFiles @OutputDirectory
38. Further Reading https://docs.gradle.org/3.5/userguide/userguide.html https://github.com/bryansills/gradle-json-verify https://github.com/evant/gradle-retrolambda https://github.com/KeepSafe/dexcount-gradle-plugin https://github.com/square/sqldelight https://github.com/trello/victor
39. Thanks! @bryansills github.com/bryansills/gradle-json-verify