Let us Ride the lightning!

Why do we need lightning network?

On an average it takes 10 minutes to make sure a transaction gets on the main blockchain, plus transaction fees on-chain is too high, it might even treat your transaction as dust, paying for coffee and everyday stuff won't be feasible given such constraints, hence it makes bitcoin network non-scalable, here enters the lightning network,which allows to make off-chain micro transactions with low transaction fees, lightning network is layer 2.

What is c-lightning?

c-lightning is c implementation of lightning network, there are other implementations too in RUST , GO , SCALA

What is c-lightning REST?

Let's say you want to make a payment portal in lightning network for a average user to help him pay for groceries, you can't expect him to operate via terminal, we need something more robust, with a good GUI, but making such an app can be tricky given that you have to talk to sockets in c-lightning, here enters c-lightning REST, which provides you with REST api inorder for the app to communicate to c-lightning.

What is RTL ?

To keep it simple, it is GooglePay for bitcoin network, will help you pay for your coffee in the near future :)

Let us setup the environment now!

Step1: Setup bitcoin node

Get the latest version of bitcoin core for bitcoincore.org

wget https://bitcoincore.org/bin/bitcoin-core-0.21.1/bitcoin-0.21.1-x86_64-linux-gnu.tar.gz

Get the corresponding signature file

wget https://bitcoincore.org/bin/bitcoin-core-0.21.1/SHA256SUMS.asc

Verify that the hash of the tar.gz file matches the one in SHA256SUMS.asc
```
sha256sum --ignore-missing --check SHA256SUMS.asc
```
Lookup the fingerprint of Bitcoin Core's release key, It should be 01EA5486DE18A882D4C2684590C8019E36C2E964, But make sure that the fingerprint is authentic by, checking with multiple sources.
```
gpg --keyserver hkp://keyserver.ubuntu.com --recv-keys 01EA5486DE18A882D4C2684590C8019E36C2E964
```
When you're sure you have the correct key, verify the signature in the signature file
```
gpg --verify SHA256SUMS.asc
```
Look for "Good signature from..." and verify that the fingerprint matches what you expect

Unpack Bitcoin Core

tar -zxvf bitcoin-0.21.1-x86_64-linux-gnu.tar.gz

navigate to the bitcoin core bin
```
cd bitcoin-0.21.1/bin
```
Start Bitcoin Core in the background (-daemon) and run on a test network, called testnet
```
./bitcoind -testnet -daemon
```
finally some fun part, have a look at data from the blockchain
```
./bitcoin-cli -tesnet getblockchaininfo
```
Look for "initialblockdownload". True means it's sill syncing
Stop Bitcoin Core
```
./bitcoin-cli -testnet stop
```

Make it always run testnet in home folder make .bitcoin directory make conf file

mkdir .bitcoin
cd .bitcoin
sudo nano ./bitcoin.conf

the content inside the config file will be

testnet=1
txindex=1
server=1
daemon=1
rpcuser=<rpcuser>
rpcpassword=<password>
zmqpubrawblock=tcp://127.0.0.1:28332
zmqpubrawtx=tcp://127.0.0.1:28333

Since we have made daemon=1 and testnet=1 we don't need those flags anymore while running our node, just running ./bitcoind in the bin file will do the job, but we still have to lead ourselves to the bin folder, let's setup bitcoin as a path variable, go to home and run nano .profile (the name of this file can change with different distros of linux) and at the end of this file add export PATH="$PATH:<path to you bitcoind>"
Run source .profile and restart your pc, voila you have your path variable enabled now, you now check your blockchain info in home, no need to direct to the bin folder.
```
bitcoin-cli getblockchaininfo
```
Let's setup bitcoin node as service in linux, this would ensure better control of this function, go to /etc/systemd/system and create a service file named bitcoind.service, an example of the service I wrote is given below, you make changes in accordance to you needs

[Unit]
Description=Bitcoin daemon
After=network.target

[Service]
ExecStartPre=/bin/sh -c 'sleep 30'
ExecStart=/home/shashank/bitcoin/bitcoin-0.21.1/bin/bitcoind -daemon -conf=/home/shashank/.bitcoin/bitcoin.conf -pid=/home/shashank/.bitcoin/bitcoind.pid
PIDFile=/home/shashank/.bitcoin/bitcoind.pid
User=shashank
Group=shashank
Type=forking
KillMode=process
Restart=always
TimeoutSec=120
RestartSec=30

[Install]
WantedBy=multi-user.target

Go to $HOME and verify your service code.

systemctl start bitcoind.service

systemctl status bitcoind.service

systemctl stop bitcoind.service

Step 2: Setup lightning node

Get all the dependencies

sudo apt-get update
sudo apt-get install -y \
autoconf automake build-essential git libtool libgmp-dev \
libsqlite3-dev python python3 net-tools zlib1g-dev

Clone lightning repo

git clone https://github.com/ElementsProject/lightning.git
cd lightning

For development or running tests, get additional dependencies:
```
sudo apt-get install -y valgrind python3-pip libpq-dev
sudo pip3 install -r requirements.txt
```
if incase sudo pip3 install -r requirements.txt throws some error, try sudo pip3 install -r requirements.lock instead and then sudo pip3 install -r requirements.txt
Build the lightning
```
./configure
make
sudo make install
```

Configure your lightning node, in $HOME create a .lightning folder and create a config file inside that directory

sudo nano ~/.lightning/config

and the content inside the config file will be

#local address
bind-addr=0.0.0.0:9430
#external address
announce-addr=<your IP>:9430
alias=<your alias>
network=testnet
rgb=003000

Forward route your router and add the port 9430 to make sure you are visible the testnet on the internet
Run your lightning node
```
lightningd/lightningd
```

Step 3: Setup c-lightning REST node

Clone the repo

git clone https://github.com/saubyk/c-lightning-REST
cd c-lightning-REST
npm install

For running the server, rename the file sample-cl-rest-config.json to cl-rest-config.json. Following parameters can be configured in the config file.
```
{
  "PORT": 3001,
  "DOCPORT": 4001,
  "PROTOCOL": "https",
  "EXECMODE": "production",
  "RPCCOMMANDS": ["*"]
}
```
Run it as an API-server via node cl-rest.js

Step4: Setup RTL

Clone repo and npm install

git clone https://github.com/Ride-The-Lightning/RTL.git
cd RTL
npm install --only=prod

Configure the RTL, copy the file Sample-RTL-Config.json from ./RTL/docs to ./RTL and rename it to RTL-Config.json, locate the complete path of the readable macroon file, it will in the c-lightning REST directory, it is used by RTL to authenticate to c-lightning REST.
modify RTL-Config.json as

{
  "multiPass": <your password, whatever you wish>,
  "port": "3000",
  "defaultNodeIndex": 1,
  "SSO": {
    "rtlSSO": 0,
    "rtlCookiePath": "",
    "logoutRedirectLink": ""
  },
  "nodes": [
    {
      "index": 1,
      "lnNode": "node 1",
      "lnImplementation": "CLT",
      "Authentication": {
        "macaroonPath": "<Complete path of the folder containing admin.macaroon for the node # 1>",
        "configPath": "<Optional:Path of the .conf if present locally or empty>"
      },
      "Settings": {
        "userPersona": "OPERATOR",
        "themeMode": "DAY",
        "themeColor": "PURPLE",
        "enableLogging": true,
        "fiatConversion": false,
        "lnServerUrl": "https://localhost:3001"
      }
    }
  ]
}