ipld-eth-beacon-indexer/internal/boot/boot.go

package boot

import (
	"fmt"
	"net/http"
	"strconv"
	"time"

	log "github.com/sirupsen/logrus"
	"github.com/vulcanize/ipld-ethcl-indexer/pkg/database/sql"
	"github.com/vulcanize/ipld-ethcl-indexer/pkg/database/sql/postgres"
	"github.com/vulcanize/ipld-ethcl-indexer/pkg/loghelper"
)

var (
	bcHealthEndpoint              = "/eth/v1/node/health"
	maxRetry                      = 5  // Max times to try to connect to the DB or BC at boot.
	retryInterval                 = 30 // The time to wait between each try.
	DB               sql.Database = &postgres.DB{}
)

// This function will ensure that we can connect to the beacon client.
// Keep in mind, the beacon client will allow you to connect to it but it might
// Not allow you to make http requests. This is part of its built in logic, and you will have
// to follow their provided guidelines. https://lighthouse-book.sigmaprime.io/api-bn.html#security
func checkBeaconClient(bcAddress string, bcPort int) error {
	log.Debug("Attempting to connect to the beacon client")
	bcEndpoint := "http://" + bcAddress + ":" + strconv.Itoa(bcPort) + bcHealthEndpoint
	resp, err := http.Get(bcEndpoint)
	if err != nil {
		loghelper.LogError(err).Error("Unable to get bc endpoint: ", bcEndpoint)
		return err
	}

	if resp.StatusCode < 200 || resp.StatusCode > 299 {
		log.Error("We recieved a non 2xx status code when checking the health of the beacon node.")
		log.Error("Health Endpoint Status Code: ", resp.StatusCode)
		return fmt.Errorf("beacon Node Provided a non 2xx status code, code provided: %d", resp.StatusCode)
	}

	log.Info("We can successfully reach the beacon client.")
	return nil

}

// A simple wrapper to create a DB object to use.
func SetupPostgresDb(dbHostname string, dbPort int, dbName string, dbUsername string, dbPassword string, driverName string) (sql.Database, error) {
	log.Debug("Resolving Driver Type")
	DbDriver, err := postgres.ResolveDriverType(driverName)
	if err != nil {
		log.WithFields(log.Fields{
			"err":                  err,
			"driver_name_provided": driverName,
		}).Error("Can't resolve driver type")
	}
	log.Info("Using Driver:", DbDriver)

	postgresConfig := postgres.Config{
		Hostname:     dbHostname,
		Port:         dbPort,
		DatabaseName: dbName,
		Username:     dbUsername,
		Password:     dbPassword,
		Driver:       DbDriver,
	}
	DB, err = postgres.NewPostgresDB(postgresConfig)

	if err != nil {
		loghelper.LogError(err).Error("Unable to connect to the DB")
		return nil, err
	}
	return DB, err

}

// This function will perform some boot operations. If any steps fail, the application will fail to start.
// Keep in mind that the DB connection can be lost later in the lifecycle of the application or
// it might not be able to connect to the beacon client.
//
// 1. Make sure the Beacon client is up.
//
// 2. Connect to the database.
//
func BootApplication(dbHostname string, dbPort int, dbName string, dbUsername string, dbPassword string, driverName string, bcAddress string, bcPort int) (sql.Database, error) {
	log.Info("Booting the Application")

	log.Debug("Checking beacon Client")
	err := checkBeaconClient(bcAddress, bcPort)
	if err != nil {
		return nil, err
	}

	log.Debug("Setting up DB connection")
	DB, err := SetupPostgresDb(dbHostname, dbPort, dbName, dbUsername, dbPassword, driverName)
	if err != nil {
		return nil, err
	}
	return DB, nil
}

// Add retry logic to ensure that we are give the Beacon Client and the DB time to start.
func BootApplicationWithRetry(dbHostname string, dbPort int, dbName string, dbUsername string, dbPassword string, driverName string, bcAddress string, bcPort int) (sql.Database, error) {
	var err error
	for i := 0; i < maxRetry; i++ {
		DB, err = BootApplication(dbHostname, dbPort, dbName, dbUsername, dbPassword, driverName, bcAddress, bcPort)
		if err != nil {
			log.WithFields(log.Fields{
				"retryNumber": i,
			}).Warn("Unable to boot application. Going to try again")
			time.Sleep(time.Duration(retryInterval) * time.Second)
			continue
		}
	}
	return DB, err
}