p4

P4 is a basic reference implementation of a Payment Protocol Server implementing the proposed BIP-270 payment flow.

This is written in go and integrates with a wallet running the Payment Protocol PayD Interface.

Exploring Endpoints

To explore the endpoints and functionality, run the server using go run cmd/rest-server/main.go and navigate to Swagger where the endpoints and their models are described in detail.

Configuring P4

The server has a series of environment variables that allow you to configure the behaviours and integrations of the server. Values can also be passed at build time to provide information such as build information, region, version etc.

Server

Key	Description	Default
SERVER_PORT	Port which this server should use	:8445
SERVER_HOST	Host name under which this server is found	p4
SERVER_SWAGGER_ENABLED	If set to true we will expose an endpoint hosting the Swagger docs	true
SERVER_SWAGGER_HOST	Sets the base url for swagger ui calls	localhost:8445

Environment / Deployment Info

Key	Description	Default
ENV_ENVIRONMENT	What enviornment we are running in, for example 'production'	dev
ENV_REGION	Region we are running in, for example 'eu-west-1'	local
ENV_COMMIT	Commit hash for the current build	test
ENV_VERSION	Semver tag for the current build, for example v1.0.0	v0.0.0
ENV_BUILDDATE	Date the code was build	Current UTC time
ENV_BITCOIN_NETWORK	What bitcoin network we are connecting to (mainnet, testnet, stn, regtest)	regtest

Logging

Key	Description	Default
LOG_LEVEL	Level of logging we want within the server (debug, error, warn, info)	info

PayD Wallet

Key	Description	Default
PAYD_HOST	Host for the wallet we are connecting to	payd
PAYD_PORT	Port the PayD wallet is listening on	:8443
PAYD_SECURE	If true the P4 server will validate the wallet TLS certs	false
PAYD_NOOP	If true we will use a dummy data store in place of payd	true

Working with P4

There are a set of makefile commands listed under the Makefile which give some useful shortcuts when working with the repo.

Some of the more common commands are listed below:

make pre-commit - ensures dependencies are up to date and runs linter and unit tests.

make build-image - builds a local docker image, useful when testing p4 in docker.

make run-compose - runs P4 in compose, a reference PayD wallet will be added to compose soon NOTE the above command will need ran first.

Rebuild on code change

You can also add an optional docker-compose.dev.yml file (this is not committed) where you can safely overwrite values or add other services without impacting the main compose file.

If you add this file, you can run it with make run-compose-dev.

The file I use has a watcher which means it auto rebuilds the image on code change and ensures compose is always up to date, this full file is shown below:

version: "3.7"

services:
  p4:
    image: theflyingcodr/go-watcher:1.15.8
    environment:
      GO111MODULE: "on"
      GOFLAGS: "-mod=vendor"
      DB_DSN: "file:data/wallet.db?cache=shared&_foreign_keys=true;"
      DB_SCHEMA_PATH: "data/sqlite/migrations"
    command: watcher -run github.com/libsv/go-p4/cmd/rest-server/ -watch github.com/libsv/go-p4
    working_dir: /go/src/github.com/libsv/go-p4
    volumes:
      - ~/git/libsv/go-p4:/go/src/github.com/libsv/go-p4

CI / CD

We use github actions to test and build the code.

If a new release is required, after your PR is approved and code added to master, simply add a new semver tag and a GitHub action will build and publish your code as well as create a GitHub release.