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Fabric gateway service

The gateway service is a generic Fabric client service that provides REST and gRPC APIs for other applications to query or invoke Fabric transactions.

Build gateway service

If you use a cloud provider, i.e., AWS, Azure, or GCP, you can use a bastion host to build and test the gateway service, and thus you do not need to install anything on your local workstation. Scripts are provided to setup the bastion host for each of the major cloud providers. Refer to the folder for AWS, Azure, or GCP for more details.

To build the service from source code for local test, you need to install the following prerequisites:

  • Download and install Go as described here
  • Download and install protoc as described here
  • Install protobuff plugin for REST over gRPC as described here i.e.,
go get -u github.com/grpc-ecosystem/grpc-gateway/protoc-gen-grpc-gateway
go get -u github.com/grpc-ecosystem/grpc-gateway/protoc-gen-swagger

You can then build and test the gateway service using the Makefile, e.g.,

# clean and build for local test on Mac
make

# test using fabric-sample byfn, assuming that the fabric-sample is installed in $GOPATH/src/github.com/hyperledger/fabric-samples/first-network
make run

# build and copy for Kubernetes, assuming that fabric network is started using '../network/network.sh start'
make dist

Start Fabric network using Kubernetes

Before starting the gateway service, you can follow the instructions in README.md to bootstrap and start a sample Fabric network using Kubernetes, i.e.,

cd ../ca
./ca-server.sh start
./ca-crypto.sh bootstrap
cd ../msp
./msp-util.sh start
./msp-util.sh bootstrap
cd ../network
./network.sh start
./network.sh test

The above sequence of commands created a Fabric network from scratch, and deployed a sample chaincode mycc to a test channel mychannel.

Start gateway service

Use the following commands to start 2 Kubernetes PODs to run the gateway service on Mac docker-desktop:

cd ../service
./gateway.sh start

On a Mac, this gateway service listens to REST requests on a NodePort: 30081. You can also run the service on a cloud provider. The scripts support AWS, Azure, and GCP. Click one of the links to see how easy it is to start a Hyperledger Fabric network in the cloud, and expose the blockchain as a public service via this gateway service.

Invoke Fabric transactions using Swagger-UI

Open the Swagger UI in Chrome web-browser: http://localhost:30081/swagger.

It defines 2 REST APIs:

  • Connection, which creates or finds a Fabric network connection, and returns the connection-ID.
  • Transaction, which invokes a Fabric transaction for query or invocation on a specified or randomly chosen endpoint.

Click Try it out for /v1/connection, and execute the following request

{
  "channel_id": "mychannel",
  "user_name": "Admin",
  "org_name": "netop1"
}

It will return a connection_id: 16453564131388984820.

Click Try it out for /v1/transaction, and execute the following query

{
  "connection_id": "16453564131388984820",
  "type": "QUERY",
  "chaincode_id": "mycc",
  "transaction": "query",
  "parameter": [
    "a"
  ]
}

It will return the current state of a on the sample Fabric channel, e.g. 90.

Click Try it out for /v1/transaction again, and execute the following transaction to reduce the value of a by 10

{
  "connection_id": "16453564131388984820",
  "type": "INVOKE",
  "chaincode_id": "mycc",
  "transaction": "invoke",
  "parameter": [
    "a","b","10"
  ]
}

Execute the above query again, it should return a reduced value of a, e.g., 80.

Note that this gateway service can be used to test any instantiated chaincode, and it supports connections to multiple channels or networks, as long as the connection is configured by using the script ./gateway.sh config [options]. You can also use a gRPC client to send API requests to the gateway service.

TODO

  • Support HTTPS and gRPCs for secure client connections.
  • Demonstrate gRPCs client app.