在這場工作坊裡，我們使用 Kotlin 以 Serverless 的方式撰寫一個 JSON API 服務，並部署到 GCP Cloud Functions 服務。本章為第二單元，讓學員了解何謂 Serverless 並對 Cloud Functions 服務有基本的認識。 詳細步驟可參考講義：http://bit.ly/ktsvless

1. (Shengyou Fan)
GDG Taichung
2021/04/17
Cloud Functions
Kotlin Serverless API
- Ch.2 Cloud Functions -
Photo by Jean-Philippe Delberghe on Unsplash

2. —
• KMM
• Kotlin Android App
• Kotlin iOS App

3. Kotlin
—
Browser
Kotlin/JS
Server
Kotlin/JVM
iOS
Kotlin/Native
Android
Kotlin/JVM

4. —
?query=param
Client Server

5. —
•
• Serverless Cloud Functions
• API Cloud Functions
• RSS Aggregator JSON API
•

6. —
• API Endpoint
• RSS
• RSS
• JSON

7. —
•
•
• ( )
• / ( )
• GCP ( )

8. —
• Serverless
• Cloud Functions
•
• Hello World
•
• GCP

9. —
Develop Build/Pack Deploy Scale Up

10. Operation …
!
Kotlin

11. Serverless
—
from Wikipedia
Serverless computing is a cloud computing execution
model in which the cloud provider runs the server,
and dynamically manages the allocation of machine
resources.
Serverless

12. —
Image source: Serverless Development With Kotlin and Kotless by Vlaadislav Tankov

13. Serverless
—
•
•
•
•

14. Google Cloud Platform
—
• GCP
• Cloud Functions Serverless
• Framework
• Cloud Functions GCP Lambda

15. Google Cloud Java
—
Java Kotlin

16. —
http://bit.ly/ktsvless

17. —

18. val invoker by configurations.creating
dependencies {
implementation("...:functions-framework-api:$ver")
invoker("...:java-function-invoker:$ver")
}
—
Cloud Function
• functions-framework-api
• java-function-invoker
Java Invoker

19. task<JavaExec>("runFunction") {
group = "gcp"
main = "com.google.cloud.functions.invoker.runner.Invoker"
classpath(invoker, sourceSets.main.get().runtimeClasspath)
args(
"--target", project.findProperty("...") ?: "",
"--port", project.findProperty("...") ?: 8080
)
}
Task
—
Gradle Task
$ ./gradlew runFunction

20. class Handler: HttpFunction {
@Throws(IOException::class)
override fun service(req: HttpRequest, res: HttpResponse) {
// ...
}
}
Handler
—
• Class
• HttpFunction (
functions-framework-api)
• service()
• req res

21. class Handler: HttpFunction {
@Throws(IOException::class)
override fun service(req: HttpRequest, res: HttpResponse) {
with(res) {
setStatusCode(HttpURLConnection.HTTP_OK)
setContentType("plain/text")
writer.write("Hello, Cloud Functions”)
}
}
}
Plain Text
—
• HTTP Status Code
• Content-Type
•

22. $ ./gradlew runFunction
-PrunFunction.target=CLASS
-PrunFunction.port=PORT
—
• Gradle Task
• Run Configuration

23. $ gcloud functions deploy PUBLIC_PATH
--region asia-east2
--runtime java11
--trigger-http
--memory 256MB
--source=build/deploy
--entry-point ENTRY_POINT_CLASS
--allow-unauthenticated
—
• gcloud