This project walks you through creating a blockchain application in Java running on AWS Lambda that interacts with your Amazon Managed Blockchain network using the Hyperledger Fabric Java SDK.

• AWS account with permissions to the following services:
  • Amazon VPC, Amazon VPC endpoints, Amazon S3, AWS Secrets Manager, AWS Lambda, Amazon API Gateway
• AWS CLI
• AWS Serverless Application Model (AWS SAM) CLI to deploy the application
• Java 8
• Gradle or Maven
• A Managed Blockchain network that is up and running in one of the supported AWS regions.
• At least one chaincode that is installed and instantiated on your blockchain network.

If you don’t have a blockchain network in your AWS account, follow the steps in Get Started Creating a Hyperledger Fabric Blockchain Network Using Amazon Managed Blockchain and complete it up to step 7 before continuing this tutorial.

The following diagram illustrates the architecture of the solution.

Clone the project from GitHub

git clone https://github.com/aws-samples/lambda-java-blockchain.git
cd lambda-java-blockchain

The two main dependencies used in the project are:

• AWS Serverless Java container: this library makes it easy to run Java applications built with frameworks such as Spring, Spring Boot, Spark in AWS Lambda
• Hyperledger Fabric Java SDK: library to read and write to the Fabric network running on Managed Blockchain.

Note: this project is built using the Spring Boot 2 quick start example

Set the AWS region of your Managed Blockchain network and copy the TLS certificate chain managedblockchain-tls-chain.pem from S3 to the project's resources folder.

export REGION=us-east-1
aws s3 cp s3://${REGION}.managedblockchain/etc/managedblockchain-tls-chain.pem  src/main/resources/managedblockchain-tls-chain.pem

Build the application using AWS SAM CLI:

sam build

The Lambda function is configured to interact with the chaincode on behalf of a new Fabric user named lambdaUser. You will need your Fabric CA admin credentials to register and enroll a new Fabric identity for lambdaUser.

Set Fabric CA Admin username and password you used to create the blockchain network, and a choose a new password for lambdaUser.

export ADMINUSER='YOUR_CA_ADMIN_USER'
export ADMINPWD='YOUR_CA_ADMIN_PASSWORD'
export LAMBDAUSERPWD='LamdaUserPwd1'

First, set the name of your blockchain network created in the prerequisites section.

export NETWORKNAME='YOUR_NETWORK_NAME'

Next, run the script deployLambda.sh to deploy the stack.

./deployLambda.sh

The script starts by exporting all the required connection information for Managed Blockchain (such as NETWORKID, MEMBERID, PEERID, PEERENDPOINT etc.).

_______________________________________
1. Exporting environment variables
_______________________________________
export REGION=us-east-1
export NETWORKID=n-XXXXXXXXXX

...

export PEERENDPOINT=nd-xxx.m-xxx.n-xxx.managedblockchain.us-east-1.amazonaws.com:30003
export AMBVpcEndpointServiceName=com.amazonaws.us-east-1.managedblockchain.n-xxx

It then creates an S3 bucket to host the Lambda source code and runs sam deploy to deploy the stack.

_______________________________________
2. Deploying the stack with 'sam deploy'
_______________________________________
Creating s3 bucket to host Lambda sources: lambda-java-blockchain-sam-bucket-xxxxxxxxxx
make_bucket: lambda-java-blockchain-sam-bucket-xxxxxxxxxx

	Deploying with following values
	===============================
	Stack name                 : lambda-java-blockchain
	Region                     : us-east-1
	Confirm changeset          : False
	Deployment s3 bucket       : lambda-java-blockchain-sam-bucket-xxxxxxxxxx
	Capabilities               : ["CAPABILITY_IAM"]
	Parameter overrides        : {'AMBREGION': 'us-east-1', ... 'AMBVpcEndpointServiceName': 'com.amazonaws.us-east-1.managedblockchain.n-xxx'}

After a successful deployment you will see an output similar to this:

CloudFormation outputs from deployed stack
---------------------------------------------------------------------------------------------------------------------------------------------------------
Outputs
---------------------------------------------------------------------------------------------------------------------------------------------------------
Key                 BlockchainLambdaApi
Description         URL for Managed Blockchain Lambda Function
Value               https://XXXXXX.execute-api.us-east-1.amazonaws.com/
---------------------------------------------------------------------------------------------------------------------------------------------------------

Successfully created/updated stack - lambda-java-blockchain in us-east-1
Lambda source code is stored in the S3 bucket - lambda-java-blockchain-sam-bucket-xxxxxxxxxx

Your stack has been successfully deployed and an API has been deployed on API-Gateway, which is accessible at https://XXXXXX.execute-api.us-east-1.amazonaws.com/. You can also retrieve the URL on the AWS CloudFormation console: find the stack named lambda-java-blockchain and choose the Outputs tab)

On this sample project, the URL of the API is publicly accessible for testing purposes. In your own application, you should protect your API; for example, by integrating with Amazon Cognito user pools. For more information about API access, see Controlling and managing access to APIs in API Gateway.

Call the /enroll-lambda-user endpoint on API-Gateway to start the enrollment process for lambdaUser.

export API_URL=$(aws cloudformation describe-stacks --stack-name lambda-java-blockchain --query "Stacks[0].Outputs[?OutputKey=='BlockchainLambdaApi'].OutputValue" --output text --region $REGION)
curl -s -X POST "${API_URL}/enroll-lambda-user"

response

lambdaUser registered and enrolled successfully

You are now ready to interact with the chaincode mycc created in Step 7 of Get Started Creating a Hyperledger Fabric Blockchain Network Using Amazon Managed Blockchain.

Let's query the balance of account a. Run curl command on your API URL and send a GET /query request as follows:

$ curl -s -X GET "${API_URL}/query?chaincodeName=mycc&functionName=query&args=a"


90

Next, invoke the chaincode to transfer 10 from account a to b. Call the endpoint POST /invoke as follows:

$ curl -s -X POST "${API_URL}/invoke" -H "Content-Type: application/json" \
    -d '{"chaincodeName": "mycc", "functionName": "invoke", "argList": ["a", "b", "10"]}'

Invoke successful

Finally, query the balance of account a, it should be decreased by 10.

$ curl -s -X GET "${API_URL}/query?chaincodeName=mycc&functionName=query&args=a"

80

This section provides few examples of reading and writing to the fabcar chaincode from fabric-samples.

Pre-requisites

• Ensure that the fabcar chaincode is installed & instantiated on your peer node.

• To install fabcar, log into your Hyperledger Fabric client EC2 instance and execute the following command:

  docker exec cli peer chaincode install -n fabcar -v v0 -p github.com/fabcar/go

• Instantiate fabcar from Hyperledger Fabric client EC2 instance with the following command:

  docker exec cli peer chaincode instantiate -o $ORDERER -C mychannel -n fabcar -v v0 \
    -c '{"Args":["initLedger"]}' \
    --cafile /opt/home/managedblockchain-tls-chain.pem --tls

The chaincode instantiation of fabcar will create 10 samples cars in the blockchain.

Use the pre-configured endpoint GET /cars/{carId} to query a car by id. Query for car with id CAR1.

$ curl -s -X GET "${API_URL}/cars/CAR1"

{"id":"CAR1","make":"Ford","model":"Mustang","colour":"red","owner":"Brad"}

To create a new car, send the request to POST /cars

$ curl -s -X POST "${API_URL}/cars" -H "Content-Type: application/json" \
    -d '{"id":"CAR20", "make":"Ford","model":"Mustang","colour":"Red","owner":"John"}'

Car created successfully

Finally, verify that you can retrieve the newly created car.

$ curl -s -X GET "${API_URL}/cars/CAR20"

{"id":"CAR20","make":"Ford","model":"Mustang","colour":"Red","owner":"John"}

To delete the AWS resources created in this project, simply delete the serverless stack with the following command:

aws cloudformation delete-stack --stack-name lambda-java-blockchain

Also delete the S3 bucket which was created in step 2

aws s3 rb s3://lambda-java-blockchain-sam-bucket-xxxxxxxxxx --force

See CONTRIBUTING for more information.

This library is licensed under the MIT-0 License. See the LICENSE file.