107 lines
2.4 KiB
Markdown
107 lines
2.4 KiB
Markdown
# How to write a Ruby gRPC client for the Lightning Network Daemon
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This section enumerates what you need to do to write a client that communicates
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with `lnd` in Ruby.
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### Introduction
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`lnd` uses the `gRPC` protocol for communication with clients like `lncli`.
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`gRPC` is based on protocol buffers and as such, you will need to compile
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the `lnd` proto file in Ruby before you can use it to communicate with `lnd`.
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### Setup
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Install gRPC rubygems:
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```
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$ gem install grpc
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$ gem install grpc-tools
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```
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Clone the Google APIs repository:
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```
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$ git clone https://github.com/googleapis/googleapis.git
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```
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Fetch the `rpc.proto` file (or copy it from your local source directory):
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```
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$ curl -o rpc.proto -s https://raw.githubusercontent.com/lightningnetwork/lnd/master/lnrpc/rpc.proto
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```
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Compile the proto file:
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```
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$ grpc_tools_ruby_protoc --proto_path googleapis:. --ruby_out=. --grpc_out=. rpc.proto
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```
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Two files will be generated in the current directory:
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* `rpc_pb.rb`
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* `rpc_services_pb.rb`
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### Example - Simple client to display wallet balance
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Every time you use the Ruby gRPC you need to require the `rpc_services_pb` file.
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We assume that `lnd` runs on the default `localhost:10009`.
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We further assume you run `lnd` with `--no-macaroons`.
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```ruby
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#!/usr/bin/env ruby
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$:.unshift(File.dirname(__FILE__))
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require 'grpc'
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require 'rpc_services_pb'
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certificate = File.read(File.expand_path("~/.lnd/tls.cert"))
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credentials = GRPC::Core::ChannelCredentials.new(certificate)
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stub = Lnrpc::Lightning::Stub.new('127.0.0.1:10009', credentials)
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response = stub.wallet_balance(Lnrpc::WalletBalanceRequest.new())
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puts "Total balance: #{response.total_balance}"
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```
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This will show the `total_balance` of the wallet.
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#### Example - Streaming client for invoice payment updates
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```ruby
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#!/usr/bin/env ruby
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$:.unshift(File.dirname(__FILE__))
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require 'grpc'
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require 'rpc_services_pb'
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certificate = File.read(File.expand_path("~/.lnd/tls.cert"))
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credentials = GRPC::Core::ChannelCredentials.new(certificate)
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stub = Lnrpc::Lightning::Stub.new('127.0.0.1:10009', credentials)
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stub.subscribe_invoices(Lnrpc::InvoiceSubscription.new) do |invoice|
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puts invoice.inspect
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end
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```
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Now, create an invoice on your node:
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```bash
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$ lncli addinvoice --amt=590
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{
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"r_hash": <R_HASH>,
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"pay_req": <PAY_REQ>
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}
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```
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Next send a payment to it from another node:
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```
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$ lncli sendpayment --pay_req=<PAY_REQ>
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```
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You should now see the details of the settled invoice appear.
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