1. Package your layer content. This means creating a .zip file archive that contains the dependencies you want to use in your functions.

2. Create the layer in Lambda.

3. Add the layer to your functions.

Topics

• Package your layer content

• Create the layer in Lambda

• Add the layer to your function

• Ensure that the Java version that Maven or Gradle refers to is the same as the Java version of the function that you intend to deploy. For example, for a Java 25 function, the mvn -v command should list Java 25 in the output.

• Your dependencies must be stored in the java/lib directory, at the root of the .zip file. For more information, see Layer paths for each Lambda runtime.

• The packages in your layer must be compatible with Linux. Lambda functions run on Amazon Linux.

To create a layer using Maven dependencies

1. Create an Apache Maven project with a pom.xml file that defines your dependencies.

   The following example includes Jackson Databind for JSON processing. The <build> section uses the maven-dependency-plugin to create separate JAR files for each dependency instead of bundling them into a single uber-jar. If you want to create an uber-jar, use the maven-shade-plugin.

   Example pom.xml

   <dependencies>
       <dependency>
           <groupId>com.fasterxml.jackson.core</groupId>
           <artifactId>jackson-databind</artifactId>
           <version>2.17.0</version>
       </dependency>
   </dependencies>
   
   <build>
       <plugins>
           <plugin>
               <groupId>org.apache.maven.plugins</groupId>
               <artifactId>maven-compiler-plugin</artifactId>
               <version>3.13.0</version>
               <configuration>
                   <source>21</source>
                   <target>21</target>
                   <release>21</release>
               </configuration>
           </plugin>
           
           <plugin>
               <groupId>org.apache.maven.plugins</groupId>
               <artifactId>maven-dependency-plugin</artifactId>
               <version>3.6.1</version>
               <executions>
                   <execution>
                       <id>copy-dependencies</id>
                       <phase>package</phase>
                       <goals>
                           <goal>copy-dependencies</goal>
                       </goals>
                       <configuration>
                           <outputDirectory>${project.build.directory}/lib</outputDirectory>
                       </configuration>
                   </execution>
               </executions>
           </plugin>
       </plugins>
   </build>

2. Build the project. This command creates all dependency JAR files in the target/lib/ directory.

   mvn clean package

3. Create the required directory structure for your layer:

   mkdir -p java/lib

4. Copy the dependency JAR files to the java/lib directory:

   cp target/lib/*.jar java/lib/

5. Zip the layer content:

   The directory structure of your .zip file should look like this:

   java/              
   └── lib/
       ├── jackson-databind-2.17.0.jar
       ├── jackson-core-2.17.0.jar
       └── jackson-annotations-2.17.0.jar

   Note

   Make sure your .zip file includes the java directory at the root level with lib inside it. This structure ensures that Lambda can locate and import your libraries. Each dependency is kept as a separate JAR file rather than bundled into an uber-jar.