2025 updates

Updated in 2025 to include major updates, related to changes in dependencies since the book was published in 2020.

These changes include:

- Updating to use Java 21, and to use the AWS Lambda Java 21 runtime
- Some minor code updates enabled by Java 21 updates vs. Java 8 - mostly just using the var keyword
- Switching to AWS SDK V2, which has syntax changes for accessing all AWS services
- Testing code updated and modified to use JUnit 5 and Mockito 5
- Various other other library updates

The original code is available in the pre-2025-updates tag.

Author: mikebroberts

.github/workflows/integration-test.yml

@@ -0,0 +1,44 @@
+name: Integration Tests
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+
+permissions:
+  id-token: write   # Required for OIDC
+  contents: read
+
+jobs:
+  integration-test:
+    runs-on: ubuntu-latest
+    timeout-minutes: 60
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-java@v4
+        with:
+          distribution: 'corretto'
+          java-version: '21'
+          cache: 'maven'
+
+      - uses: aws-actions/setup-sam@v2
+        with:
+          use-installer: true
+
+      - uses: aws-actions/configure-aws-credentials@v4
+        with:
+          role-to-assume: arn:aws:iam::397589511426:role/account-wide-resources-GithubActionsRole-1CAIKQPYM5WD3
+          aws-region: us-east-1
+
+      - run: ./deploy-all.sh
+        working-directory: ./test-harness
+
+      - run: ./test-all.sh
+        working-directory: ./test-harness
+
+      - if: always()
+        run: ./teardown-all.sh
+        working-directory: ./test-harness

README.md

@@ -10,6 +10,21 @@ For more info on the book itself, see:
 * [O'Reilly's Page](http://shop.oreilly.com/product/0636920178101.do)
 * [The book on Amazon](https://www.amazon.com/Programming-AWS-Lambda-Serverless-Applications/dp/149204105X)
 
+## 2025 updates
+
+This current branch of the code was updated in 2025 to include major updates, related to changes in
+dependencies since the book was published in 2020. These changes include:
+
+* Updating to use Java 21, and to use the AWS Lambda Java 21 runtime
+* Some minor code updates enabled by Java 21 updates vs. Java 8 - mostly just using the `var` keyword
+* Switching to AWS SDK V2, which has syntax changes for accessing all AWS services
+* Testing code updated and modified to use JUnit 5 and Mockito 5
+* Various other other library updates
+
+The original code is available in the [pre-2025-updates tag](https://github.com/symphoniacloud/programming-aws-lambda-book/releases/tag/pre-2025-updates).
+
+## Miscellaneous other changes
+
 For errata and updates, please see [this page](ErrataAndUpdates.md).
 
 We plan on adding blog entries too - keep your eyes peeled on [our blog](https://blog.symphonia.io/) and [our Twitter](https://twitter.com/symphoniacloud).

chapter2/pom.xml

@@ -10,16 +10,16 @@
   <version>1.0-SNAPSHOT</version>
 
   <properties>
-    <maven.compiler.source>1.8</maven.compiler.source>
-    <maven.compiler.target>1.8</maven.compiler.target>
+    <maven.compiler.release>21</maven.compiler.release>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
   </properties>
 
   <build>
     <plugins>
       <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-shade-plugin</artifactId>
-        <version>3.2.1</version>
+        <version>3.6.1</version>
         <executions>
           <execution>
             <phase>package</phase>

chapter2/template.yaml

@@ -7,7 +7,7 @@ Resources:
   HelloWorldLambda:
     Type: AWS::Serverless::Function
     Properties:
-      Runtime: java8
+      Runtime: java21
       MemorySize: 512
       Handler: book.HelloWorld::handler
       CodeUri: target/lambda.jar

chapter3/pom.xml

@@ -10,16 +10,16 @@
   <version>1.0-SNAPSHOT</version>
 
   <properties>
-    <maven.compiler.source>1.8</maven.compiler.source>
-    <maven.compiler.target>1.8</maven.compiler.target>
+    <maven.compiler.release>21</maven.compiler.release>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
   </properties>
 
   <build>
     <plugins>
       <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-shade-plugin</artifactId>
-        <version>3.2.1</version>
+        <version>3.6.1</version>
         <executions>
           <execution>
             <phase>package</phase>
@@ -39,7 +39,7 @@
     <dependency>
       <groupId>com.amazonaws</groupId>
       <artifactId>aws-lambda-java-core</artifactId>
-      <version>1.2.0</version>
+      <version>1.4.0</version>
       <scope>provided</scope>
     </dependency>
   </dependencies>

chapter3/src/main/java/book/ContextLambda.java

@@ -7,7 +7,7 @@
 
 public class ContextLambda {
     public Map<String, Object> handler(Object input, Context context) {
-        Map<String, Object> toReturn = new HashMap<>();
+        var toReturn = new HashMap<String, Object>();
         toReturn.put("getMemoryLimitInMB", context.getMemoryLimitInMB() + "");
         toReturn.put("getFunctionName", context.getFunctionName());
         toReturn.put("getFunctionVersion", context.getFunctionVersion());

chapter3/src/main/java/book/EnvVarLambda.java

@@ -2,7 +2,7 @@
 
 public class EnvVarLambda {
     public void handler(Object event) {
-        String databaseUrl = System.getenv("DATABASE_URL");
+        var databaseUrl = System.getenv("DATABASE_URL");
         if (databaseUrl == null || databaseUrl.isEmpty())
             System.out.println("DATABASE_URL is not set");
         else

chapter3/src/main/java/book/ListMapLambda.java

@@ -8,19 +8,19 @@
 
 public class ListMapLambda {
     public List<Integer> handlerList(List<Integer> input) {
-        List<Integer> newList = new ArrayList<>();
+        var newList = new ArrayList<Integer>();
         input.forEach(x -> newList.add(100 + x));
         return newList;
     }
 
     public Map<String, String> handlerMap(Map<String, String> input) {
-        Map<String, String> newMap = new HashMap<>();
+        var newMap = new HashMap<String, String>();
         input.forEach((k, v) -> newMap.put("New Map -> " + k, v));
         return newMap;
     }
 
     public Map<String, Map<String, Integer>> handlerNestedCollection(List<Map<String, Integer>> input) {
-        Map<String, Map<String, Integer>> newMap = new HashMap<>();
+        var newMap = new HashMap<String, Map<String, Integer>>();
         IntStream.range(0, input.size())
                 .forEach(i -> newMap.put("Nested at position " + i, input.get(i)));
         return newMap;

chapter3/src/main/java/book/WhatIsMyLambdaEvent.java

@@ -5,7 +5,7 @@
 
 public class WhatIsMyLambdaEvent {
     public void handler(InputStream is, OutputStream os) {
-        java.util.Scanner s = new java.util.Scanner(is).useDelimiter("\\A");
+        var s = new java.util.Scanner(is).useDelimiter("\\A");
         System.out.println(s.hasNext() ? s.next() : "No input detected");
     }
 }

chapter3/template.yaml

@@ -9,7 +9,7 @@ Resources:
     Properties:
       FunctionName: HelloWorldJava
       Timeout: 2
-      Runtime: java8
+      Runtime: java21
       MemorySize: 512
       Handler: book.EnvVarLambda::handler
       CodeUri: target/lambda.jar