node-pinger

A microservice that:

• Retrieves the latest block known by a BTC node
• Queries the BTC node about block information

WIP (as of 7 Jun 2019):

1. Compatibility with SupervisorD ✅
2. Standardadisation with go-module. ✅
3. Logging
4. Containerisation (Docker)
5. Front-End with Angular

Install

Preparation on the RPC Server side
Locate the bitcoin.conf file of your target BTC node, and therein

• Check that server=1 so that the ir accepts JSON-RPC commands;
• Make sure you locate the values of the parameters rpcuser, and rpcpassword; You'll need them later for RPC_USER, RPC_PASS. (Never use this as your wallet password.)
• Take note of the parameter rpcport –usually set at 8332, please keep it that way–, and also of the IP address of the node. You'll use them together later as, eg RPC_HOST=192.168.1.100:8332;
• Make sure that the system from which you'll execute this code is included in rcpallowip (to allow within the local network, try something like 192.168.1.1/24, and please never set it to *).

Compilation
While in /path/to/node-pinger execute:

go get ./btcinfo/...
go build -o btcinfo/bin/btcinfo btcinfo/cmd/main.go

This will get the dependencies, and create the binary of the btcinfo service to be executed by Supervisord.

Configuration files, {supervisord,btcinfo}.conf
Locate the files /path/to/node-pinger/btcinfo.

In the file supervisord.example.conf, adequate the following line:

files=/path/to/node-pinger/btcinfo/btcinfo.conf

and copy the file as supervisor.conf (don't worry, it's .gitignored).

In the file btcinfo.example.conf, adequate the following lines according to the values you got from the RPC Server (as mentioned above):

directory=/path/to/btcinfo
command=/path/to/btcinfo/bin/btcinfo
environment=RPC_HOST="192.168.1.100:8332",RPC_USER="YOUR_USER",RPC_PASS="YOUR_PASSWORD"

and copy the file as btcinfo.conf (don't worry, it's also .gitignored).

Running with Supervisord
Assuming you have Supervisord installed (macOS: brew install supervisord), execute:

sudo supervisord -c btcinfo/supervisord.conf

and the service will be running on your system on port 8080.

Usage

Endpoints

• GET /
  • Will retrieve the latest block of the node, eg {latestBlock: 579375}
• GET /blocks?hash=HASH_OF_THE_BLOCK_IN_QUESTION
  • TODO: Move to or add endpoint /blocks/{hash}
  • Will retrieve information of the block with the hash you give as JSON.
  • (See note on verbosity regarding the parameter tx of the response)

Note on verbosity of the RPC server
The library used by this command, github.com/btcsuite/btcd/btcjson as a one-to-one implementation of the RPC commands. This module offers two functions to retrieve block information: getTxsFromBlockHash and getTxsFromBlockHashTx.
Although the second is more verbose about the parameter tx of the response, This command uses the first. The reason lies in a (only partially documented) change of signature of the corresponding RPC CLI command getblock.

TL;DR: If you need more verbose information, you need to replace the library with this pull request and follow the instructions there.