There are three ways to build a container image for a Java Lambda function:
This page explains how to build, test, and deploy container images for Lambda.
AWS base images for JavaAWS provides the following base images for Java:
Amazon ECR repository: gallery.ecr.aws/lambda/java
The Java 21 and later base images are based on the Amazon Linux 2023 minimal container image. Earlier base images use Amazon Linux 2. AL2023 provides several advantages over Amazon Linux 2, including a smaller deployment footprint and updated versions of libraries such as glibc
.
AL2023-based images use microdnf
(symlinked as dnf
) as the package manager instead of yum
, which is the default package manager in Amazon Linux 2. microdnf
is a standalone implementation of dnf
. For a list of packages that are included in AL2023-based images, refer to the Minimal Container columns in Comparing packages installed on Amazon Linux 2023 Container Images. For more information about the differences between AL2023 and Amazon Linux 2, see Introducing the Amazon Linux 2023 runtime for AWS Lambda on the AWS Compute Blog.
To run AL2023-based images locally, including with AWS Serverless Application Model (AWS SAM), you must use Docker version 20.10.10 or later.
Using an AWS base image for JavaRun the following command to create a Maven project using the archetype for Lambda. The following parameters are required:
service â The AWS service client to use in the Lambda function. For a list of available sources, see aws-sdk-java-v2/services on GitHub.
region â The AWS Region where you want to create the Lambda function.
groupId â The full package namespace of your application.
artifactId â Your project name. This becomes the name of the directory for your project.
In Linux and macOS, run this command:
mvn -B archetype:generate \
-DarchetypeGroupId=software.amazon.awssdk \
-DarchetypeArtifactId=archetype-lambda -Dservice=s3
-Dregion=US_WEST_2
\
-DgroupId=com.example.myapp
\
-DartifactId=myapp
In PowerShell, run this command:
mvn -B archetype:generate `
"-DarchetypeGroupId=software.amazon.awssdk" `
"-DarchetypeArtifactId=archetype-lambda" "-Dservice=s3
" "-Dregion=US_WEST_2
" `
"-DgroupId=com.example.myapp
" `
"-DartifactId=myapp
"
The Maven archetype for Lambda is preconfigured to compile with Java SE 8 and includes a dependency to the AWS SDK for Java. If you create your project with a different archetype or by using another method, you must configure the Java compiler for Maven and declare the SDK as a dependency.
Open the
directory, and find the myapp
/src/main/java/com/example/myapp
App.java
file. This is the code for the Lambda function. You can use the provided sample code for testing, or replace it with your own.
Navigate back to the project's root directory, and then create a new Dockerfile with the following configuration:
Note that the example Dockerfile does not include a USER instruction. When you deploy a container image to Lambda, Lambda automatically defines a default Linux user with least-privileged permissions. This is different from standard Docker behavior which defaults to the root
user when no USER
instruction is provided.
FROM public.ecr.aws/lambda/java:21
# Copy function code and runtime dependencies from Maven layout
COPY target/classes ${LAMBDA_TASK_ROOT}
COPY target/dependency/* ${LAMBDA_TASK_ROOT}/lib/
# Set the CMD to your handler (could also be done as a parameter override outside of the Dockerfile)
CMD [ "com.example.myapp.App::handleRequest" ]
Compile the project and collect the runtime dependencies.
mvn compile dependency:copy-dependencies -DincludeScope=runtime
Build the Docker image with the docker build command. The following example names the image docker-image
and gives it the test
tag. To make your image compatible with Lambda, you must use the --provenance=false
option.
docker buildx build --platform linux/amd64 --provenance=false -t docker-image
:test
.
Note
The command specifies the --platform linux/amd64
option to ensure that your container is compatible with the Lambda execution environment regardless of the architecture of your build machine. If you intend to create a Lambda function using the ARM64 instruction set architecture, be sure to change the command to use the --platform linux/arm64
option instead.
Create a directory for the project, and then switch to that directory.
mkdir example
cd example
Run the following command to have Gradle generate a new Java application project in the example
directory in your environment. For Select build script DSL, choose 2: Groovy.
gradle init --type java-application
Open the /
directory, and find the example
/app/src/main/java/example
App.java
file. This is the code for the Lambda function. You can use the following sample code for testing, or replace it with your own.
package com.example;
import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.RequestHandler;
public class App implements RequestHandler<Object, String> {
public String handleRequest(Object input, Context context) {
return "Hello world!";
}
}
Open the build.gradle
file. If you're using the sample function code from the previous step, replace the contents of build.gradle
with the following. If you're using your own function code, modify your build.gradle
file as needed.
plugins {
id 'java'
}
group 'com.example'
version '1.0-SNAPSHOT'
sourceCompatibility = 1.8
repositories {
mavenCentral()
}
dependencies {
implementation 'com.amazonaws:aws-lambda-java-core:1.2.1'
}
jar {
manifest {
attributes 'Main-Class': 'com.example.App'
}
}
The gradle init
command from step 2 also generated a dummy test case in the app/test
directory. For the purposes of this tutorial, skip running tests by deleting the /test
directory.
Build the project.
gradle build
In the project's root directory (/example
), create a Dockerfile with the following configuration:
Note that the example Dockerfile does not include a USER instruction. When you deploy a container image to Lambda, Lambda automatically defines a default Linux user with least-privileged permissions. This is different from standard Docker behavior which defaults to the root
user when no USER
instruction is provided.
FROM public.ecr.aws/lambda/java:21
# Copy function code and runtime dependencies from Gradle layout
COPY app/build/classes/java/main ${LAMBDA_TASK_ROOT}
# Set the CMD to your handler (could also be done as a parameter override outside of the Dockerfile)
CMD [ "com.example.App::handleRequest" ]
Build the Docker image with the docker build command. The following example names the image docker-image
and gives it the test
tag. To make your image compatible with Lambda, you must use the --provenance=false
option.
docker buildx build --platform linux/amd64 --provenance=false -t docker-image
:test
.
Note
The command specifies the --platform linux/amd64
option to ensure that your container is compatible with the Lambda execution environment regardless of the architecture of your build machine. If you intend to create a Lambda function using the ARM64 instruction set architecture, be sure to change the command to use the --platform linux/arm64
option instead.
Start the Docker image with the docker run command. In this example, docker-image
is the image name and test
is the tag.
docker run --platform linux/amd64 -p 9000:8080 docker-image
:test
This command runs the image as a container and creates a local endpoint at localhost:9000/2015-03-31/functions/function/invocations
.
If you built the Docker image for the ARM64 instruction set architecture, be sure to use the --platform linux/
option instead of arm64
--platform linux/
.amd64
From a new terminal window, post an event to the local endpoint.
In Linux and macOS, run the following curl
command:
curl "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{}'
This command invokes the function with an empty event and returns a response. If you're using your own function code rather than the sample function code, you might want to invoke the function with a JSON payload. Example:
curl "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{"payload":"hello world!"}
'
In PowerShell, run the following Invoke-WebRequest
command:
Invoke-WebRequest -Uri "http://localhost:9000/2015-03-31/functions/function/invocations" -Method Post -Body '{}' -ContentType "application/json"
This command invokes the function with an empty event and returns a response. If you're using your own function code rather than the sample function code, you might want to invoke the function with a JSON payload. Example:
Invoke-WebRequest -Uri "http://localhost:9000/2015-03-31/functions/function/invocations" -Method Post -Body '{"payload":"hello world!"}
' -ContentType "application/json"
Get the container ID.
docker ps
Use the docker kill command to stop the container. In this command, replace 3766c4ab331c
with the container ID from the previous step.
docker kill 3766c4ab331c
Run the get-login-password command to authenticate the Docker CLI to your Amazon ECR registry.
Set the --region
value to the AWS Region where you want to create the Amazon ECR repository.
Replace 111122223333
with your AWS account ID.
aws ecr get-login-password --region us-east-1
| docker login --username AWS --password-stdin 111122223333
.dkr.ecr.us-east-1
.amazonaws.com
Create a repository in Amazon ECR using the create-repository command.
aws ecr create-repository --repository-name hello-world
--region us-east-1
--image-scanning-configuration scanOnPush=true --image-tag-mutability MUTABLE
Note
The Amazon ECR repository must be in the same AWS Region as the Lambda function.
If successful, you see a response like this:
{
"repository": {
"repositoryArn": "arn:aws:ecr:us-east-1:111122223333:repository/hello-world",
"registryId": "111122223333",
"repositoryName": "hello-world",
"repositoryUri": "111122223333.dkr.ecr.us-east-1.amazonaws.com/hello-world",
"createdAt": "2023-03-09T10:39:01+00:00",
"imageTagMutability": "MUTABLE",
"imageScanningConfiguration": {
"scanOnPush": true
},
"encryptionConfiguration": {
"encryptionType": "AES256"
}
}
}
Copy the repositoryUri
from the output in the previous step.
Run the docker tag command to tag your local image into your Amazon ECR repository as the latest version. In this command:
docker-image:test
is the name and tag of your Docker image. This is the image name and tag that you specified in the docker build
command.
Replace <ECRrepositoryUri>
with the repositoryUri
that you copied. Make sure to include :latest
at the end of the URI.
docker tag docker-image:test <ECRrepositoryUri>
:latest
Example:
docker tag docker-image
:test
111122223333
.dkr.ecr.us-east-1
.amazonaws.com/hello-world
:latest
Run the docker push command to deploy your local image to the Amazon ECR repository. Make sure to include :latest
at the end of the repository URI.
docker push 111122223333
.dkr.ecr.us-east-1
.amazonaws.com/hello-world
:latest
Create an execution role for the function, if you don't already have one. You need the Amazon Resource Name (ARN) of the role in the next step.
Create the Lambda function. For ImageUri
, specify the repository URI from earlier. Make sure to include :latest
at the end of the URI.
aws lambda create-function \
--function-name hello-world
\
--package-type Image \
--code ImageUri=111122223333
.dkr.ecr.us-east-1
.amazonaws.com/hello-world
:latest \
--role arn:aws:iam::111122223333:role/lambda-ex
Note
You can create a function using an image in a different AWS account, as long as the image is in the same Region as the Lambda function. For more information, see Amazon ECR cross-account permissions.
Invoke the function.
aws lambda invoke --function-name hello-world
response.json
You should see a response like this:
{
"ExecutedVersion": "$LATEST",
"StatusCode": 200
}
To see the output of the function, check the response.json
file.
To update the function code, you must build the image again, upload the new image to the Amazon ECR repository, and then use the update-function-code command to deploy the image to the Lambda function.
Lambda resolves the image tag to a specific image digest. This means that if you point the image tag that was used to deploy the function to a new image in Amazon ECR, Lambda doesn't automatically update the function to use the new image.
To deploy the new image to the same Lambda function, you must use the update-function-code command, even if the image tag in Amazon ECR remains the same. In the following example, the --publish
option creates a new version of the function using the updated container image.
aws lambda update-function-code \
--function-name hello-world
\
--image-uri 111122223333.dkr.ecr.us-east-1.amazonaws.com/hello-world:latest
\
--publish
Using an alternative base image with the runtime interface client
If you use an OS-only base image or an alternative base image, you must include the runtime interface client in your image. The runtime interface client extends the Runtime API, which manages the interaction between Lambda and your function code.
Install the runtime interface client for Java in your Dockerfile, or as a dependency in your project. For example, to install the runtime interface client using the Maven package manager, add the following to your pom.xml
file:
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-lambda-java-runtime-interface-client</artifactId>
<version>2.3.2</version>
</dependency>
For package details, see AWS Lambda Java Runtime Interface Client in the Maven Central Repository. You can also review the runtime interface client source code in the AWS Lambda Java Support Libraries GitHub repository.
The following example demonstrates how to build a container image for Java using an Amazon Corretto image. Amazon Corretto is a no-cost, multiplatform, production-ready distribution of the Open Java Development Kit (OpenJDK). The Maven project includes the runtime interface client as a dependency.
Create a Maven project. The following parameters are required:
groupId â The full package namespace of your application.
artifactId â Your project name. This becomes the name of the directory for your project.
mvn -B archetype:generate \
-DarchetypeArtifactId=maven-archetype-quickstart \
-DgroupId=example
\
-DartifactId=myapp
\
-DinteractiveMode=false
mvn -B archetype:generate `
-DarchetypeArtifactId=maven-archetype-quickstart `
-DgroupId=example
`
-DartifactId=myapp
`
-DinteractiveMode=false
Open the project directory.
cd myapp
Open the pom.xml
file and replace the contents with the following. This file includes the aws-lambda-java-runtime-interface-client as a dependency. Alternatively, you can install the runtime interface client in the Dockerfile. However, the simplest approach is to include the library as a dependency.
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>example</groupId>
<artifactId>hello-lambda</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>hello-lambda</name>
<url>http://maven.apache.org</url>
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-lambda-java-runtime-interface-client
</artifactId>
<version>2.3.2
</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>3.1.2</version>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
Open the
directory, and find the myapp
/src/main/java/com/example/myapp
App.java
file. This is the code for the Lambda function. Replace the code with the following.
package example;
public class App {
public static String sayHello() {
return "Hello world!";
}
}
The mvn -B archetype:generate
command from step 1 also generated a dummy test case in the src/test
directory. For the purposes of this tutorial, skip over running tests by deleting this entire generated /test
directory.
Navigate back to the project's root directory, and then create a new Dockerfile. The following example Dockerfile uses an Amazon Corretto image. Amazon Corretto is a no-cost, multiplatform, production-ready distribution of the OpenJDK.
Set the FROM
property to the URI of the base image.
Set the ENTRYPOINT
to the module that you want the Docker container to run when it starts. In this case, the module is the runtime interface client.
Set the CMD
argument to the Lambda function handler.
Note that the example Dockerfile does not include a USER instruction. When you deploy a container image to Lambda, Lambda automatically defines a default Linux user with least-privileged permissions. This is different from standard Docker behavior which defaults to the root
user when no USER
instruction is provided.
FROM public.ecr.aws/amazoncorretto/amazoncorretto:21
as base
# Configure the build environment
FROM base as build
RUN yum install -y maven
WORKDIR /src
# Cache and copy dependencies
ADD pom.xml .
RUN mvn dependency:go-offline dependency:copy-dependencies
# Compile the function
ADD . .
RUN mvn package
# Copy the function artifact and dependencies onto a clean base
FROM base
WORKDIR /function
COPY --from=build /src/target/dependency/*.jar ./
COPY --from=build /src/target/*.jar ./
# Set runtime interface client as default command for the container runtime
ENTRYPOINT [ "/usr/bin/java", "-cp", "./*", "com.amazonaws.services.lambda.runtime.api.client.AWSLambda
" ]
# Pass the name of the function handler as an argument to the runtime
CMD [ "example.App::sayHello
" ]
Build the Docker image with the docker build command. The following example names the image docker-image
and gives it the test
tag. To make your image compatible with Lambda, you must use the --provenance=false
option.
docker buildx build --platform linux/amd64 --provenance=false -t docker-image
:test
.
Note
The command specifies the --platform linux/amd64
option to ensure that your container is compatible with the Lambda execution environment regardless of the architecture of your build machine. If you intend to create a Lambda function using the ARM64 instruction set architecture, be sure to change the command to use the --platform linux/arm64
option instead.
Use the runtime interface emulator to locally test the image. You can build the emulator into your image or use the following procedure to install it on your local machine.
To install and run the runtime interface emulator on your local machineFrom your project directory, run the following command to download the runtime interface emulator (x86-64 architecture) from GitHub and install it on your local machine.
mkdir -p ~/.aws-lambda-rie && \
curl -Lo ~/.aws-lambda-rie/aws-lambda-rie https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie && \
chmod +x ~/.aws-lambda-rie/aws-lambda-rie
To install the arm64 emulator, replace the GitHub repository URL in the previous command with the following:
https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie-arm64
$dirPath = "$HOME\.aws-lambda-rie"
if (-not (Test-Path $dirPath)) {
New-Item -Path $dirPath -ItemType Directory
}
$downloadLink = "https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie"
$destinationPath = "$HOME\.aws-lambda-rie\aws-lambda-rie"
Invoke-WebRequest -Uri $downloadLink -OutFile $destinationPath
To install the arm64 emulator, replace the $downloadLink
with the following:
https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie-arm64
Start the Docker image with the docker run command. Note the following:
docker-image
is the image name and test
is the tag.
/usr/bin/java -cp './*' com.amazonaws.services.lambda.runtime.api.client.AWSLambda example.App::sayHello
is the ENTRYPOINT
followed by the CMD
from your Dockerfile.
docker run --platform linux/amd64 -d -v ~/.aws-lambda-rie:/aws-lambda -p 9000:8080 \
--entrypoint /aws-lambda/aws-lambda-rie \
docker-image:test
\
/usr/bin/java -cp './*' com.amazonaws.services.lambda.runtime.api.client.AWSLambda example.App::sayHello
docker run --platform linux/amd64 -d -v "$HOME\.aws-lambda-rie:/aws-lambda" -p 9000:8080 `
--entrypoint /aws-lambda/aws-lambda-rie `
docker-image:test
`
/usr/bin/java -cp './*' com.amazonaws.services.lambda.runtime.api.client.AWSLambda example.App::sayHello
This command runs the image as a container and creates a local endpoint at localhost:9000/2015-03-31/functions/function/invocations
.
If you built the Docker image for the ARM64 instruction set architecture, be sure to use the --platform linux/
option instead of arm64
--platform linux/
.amd64
Post an event to the local endpoint.
In Linux and macOS, run the following curl
command:
curl "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{}'
This command invokes the function with an empty event and returns a response. If you're using your own function code rather than the sample function code, you might want to invoke the function with a JSON payload. Example:
curl "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{"payload":"hello world!"}
'
In PowerShell, run the following Invoke-WebRequest
command:
Invoke-WebRequest -Uri "http://localhost:9000/2015-03-31/functions/function/invocations" -Method Post -Body '{}' -ContentType "application/json"
This command invokes the function with an empty event and returns a response. If you're using your own function code rather than the sample function code, you might want to invoke the function with a JSON payload. Example:
Invoke-WebRequest -Uri "http://localhost:9000/2015-03-31/functions/function/invocations" -Method Post -Body '{"payload":"hello world!"}
' -ContentType "application/json"
Get the container ID.
docker ps
Use the docker kill command to stop the container. In this command, replace 3766c4ab331c
with the container ID from the previous step.
docker kill 3766c4ab331c
Run the get-login-password command to authenticate the Docker CLI to your Amazon ECR registry.
Set the --region
value to the AWS Region where you want to create the Amazon ECR repository.
Replace 111122223333
with your AWS account ID.
aws ecr get-login-password --region us-east-1
| docker login --username AWS --password-stdin 111122223333
.dkr.ecr.us-east-1
.amazonaws.com
Create a repository in Amazon ECR using the create-repository command.
aws ecr create-repository --repository-name hello-world
--region us-east-1
--image-scanning-configuration scanOnPush=true --image-tag-mutability MUTABLE
Note
The Amazon ECR repository must be in the same AWS Region as the Lambda function.
If successful, you see a response like this:
{
"repository": {
"repositoryArn": "arn:aws:ecr:us-east-1:111122223333:repository/hello-world",
"registryId": "111122223333",
"repositoryName": "hello-world",
"repositoryUri": "111122223333.dkr.ecr.us-east-1.amazonaws.com/hello-world",
"createdAt": "2023-03-09T10:39:01+00:00",
"imageTagMutability": "MUTABLE",
"imageScanningConfiguration": {
"scanOnPush": true
},
"encryptionConfiguration": {
"encryptionType": "AES256"
}
}
}
Copy the repositoryUri
from the output in the previous step.
Run the docker tag command to tag your local image into your Amazon ECR repository as the latest version. In this command:
docker-image:test
is the name and tag of your Docker image. This is the image name and tag that you specified in the docker build
command.
Replace <ECRrepositoryUri>
with the repositoryUri
that you copied. Make sure to include :latest
at the end of the URI.
docker tag docker-image:test <ECRrepositoryUri>
:latest
Example:
docker tag docker-image
:test
111122223333
.dkr.ecr.us-east-1
.amazonaws.com/hello-world
:latest
Run the docker push command to deploy your local image to the Amazon ECR repository. Make sure to include :latest
at the end of the repository URI.
docker push 111122223333
.dkr.ecr.us-east-1
.amazonaws.com/hello-world
:latest
Create an execution role for the function, if you don't already have one. You need the Amazon Resource Name (ARN) of the role in the next step.
Create the Lambda function. For ImageUri
, specify the repository URI from earlier. Make sure to include :latest
at the end of the URI.
aws lambda create-function \
--function-name hello-world
\
--package-type Image \
--code ImageUri=111122223333
.dkr.ecr.us-east-1
.amazonaws.com/hello-world
:latest \
--role arn:aws:iam::111122223333:role/lambda-ex
Note
You can create a function using an image in a different AWS account, as long as the image is in the same Region as the Lambda function. For more information, see Amazon ECR cross-account permissions.
Invoke the function.
aws lambda invoke --function-name hello-world
response.json
You should see a response like this:
{
"ExecutedVersion": "$LATEST",
"StatusCode": 200
}
To see the output of the function, check the response.json
file.
To update the function code, you must build the image again, upload the new image to the Amazon ECR repository, and then use the update-function-code command to deploy the image to the Lambda function.
Lambda resolves the image tag to a specific image digest. This means that if you point the image tag that was used to deploy the function to a new image in Amazon ECR, Lambda doesn't automatically update the function to use the new image.
To deploy the new image to the same Lambda function, you must use the update-function-code command, even if the image tag in Amazon ECR remains the same. In the following example, the --publish
option creates a new version of the function using the updated container image.
aws lambda update-function-code \
--function-name hello-world
\
--image-uri 111122223333.dkr.ecr.us-east-1.amazonaws.com/hello-world:latest
\
--publish
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