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Create Java Lambda Function

Where we demonstrate creating a Lambda function written in Java on the Java 21 runtime.

A Windows 11 workstation was used for the process below.

IMPORTANT a free account registration is required to download the Oracle JDK

Prerequisites

  1. Java Development Kit (JDK) - login required
    • Java Development Kit (JDK) version 21
    • https://www.oracle.com/java/technologies/downloads/
    • Download the Windows x64 installer
    • Run the installer (Defaults are fine)
      • C:\Program Files\Java\jdk-21\
    • Environment variables
      • Search for "Edit the system environment variables" in the Windows search bar
      • Click Environment Variables in the System Properties window
      • Under System variables, click New...
        • Variable name: JAVA_HOME
        • Variable value: set to the JDK installation directory (e.g., C:\Program Files\Java\jdk-21).
        • Click OK and then click OK
    • Verify from command line
      • java -version
      • javac -version
  2. Install Maven
    • https://maven.apache.org/download.cgi
    • Select and download "Binary zip archive" (for Windows)
    • Unzip the file to your desired installation directory (e.g., C:\Program Files\Apache\maven)
    • Environment variables
      • Search for "Edit the system environment variables" in the Windows search bar
      • Click Environment Variables in the System Properties window
      • Under System variables, click New...
        • Variable name: M2_HOME
        • Variable value: set to the Maven installation directory (e.g., C:\Program Files\Apache\maven).
      • Under System variables, edit Path
        • Click New
        • Add the path to the bin directory inside the Maven directory (e.g. C:\Program Files\Apache\maven\bin)
    • Test from command line (open a new command prompt if needed)
      • mvn -version

Create the Project

  1. Open a terminal and navigate to your desired project directory
  2. mkdir my-java-lambda-project
  3. cd my-java-lambda-project
  4. Create a file pom.xml in your project folder root with the contents of pom.xml
  5. mkdir src
  6. mkdir src\main
  7. mkdir src\main\java
  8. mkdir src\main\java\com
  9. mkdir src\main\java\com\doritoes
  10. cd src\main\java\com\doritoes
  11. Create a file in src/main/java/com/doritoes named MyRequestHandler.java with the contents of lambda_test.java

Build

  1. Open command line in the project folder (e.g., my-java-lambda-project)
  2. mvn clean package
  3. The jar file will be created in the target folder
    • similar to MyRequestHandler-1.0-SNAPSHOT.jar
    • this is the JAR file containing your compiled Java code

Create function

Log in to AWS Console and Navigate to Lamba

  1. Browse to (https://console.aws.amazon.com) and log in
  2. In the search bar enter "Lamba" and click on Lambda

Create our Function

  1. Click Create a function
    1. Author from scratch
    2. Function name: myIPFunctionJava
    3. Runtime: Java 21
    4. Change the default Handler from example.Hello::handleRequest to com.doritoes.MyRequestHandler::handleRequest
    5. Architecture: the architecture you build your function for
      • make sure it matches the function you built
    6. Leave the rest at defaults, click Create function
  2. In the Code source pane, click Upload from > .jar file
    • Click Upload, select file MyRequestHandler-1.0-SNAPSHOT.jar within your target folder, and click Save
  3. Click Test
    • For the test event
      • Event name: Test
      • Test Event JSON: test_event.json
        • This provides a dummy IP address for the test to work
      • Click Save
    • Click Test and the test should succeed