antelope-api-healthcheck/cmd/antelope-api-healtcheck/main.go

package main

import (
	"fmt"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/eosswedenorg-go/pid"
	"github.com/eosswedenorg/antelope-api-healthcheck/internal/server"
	"github.com/eosswedenorg/antelope-api-healthcheck/internal/utils"
	log "github.com/inconshreveable/log15"
	"github.com/pborman/getopt/v2"
)

//  Command line flags
// ---------------------------------------------------------

var (
	logFile string
	pidFile string
)

//  Global variables
// ---------------------------------------------------------

// Version string, should be updated by the go linker (by passing "-X main.VersionString=value" to the linker)
// see: https://pkg.go.dev/cmd/link
var VersionString string = "-"

// File descriptor to the current log file.
var logfd *os.File

var (
	logfmt log.Format
	logger log.Logger

	// TCP Server
	srv *server.Server
)

//	argv_listen_addr
//	  Parse listen address from command line.
//
// ---------------------------------------------------------
func argv_listen_addr() string {
	var addr string

	argv := getopt.Args()
	if len(argv) > 0 {
		addr = argv[0]
	} else {
		addr = "127.0.0.1"
	}

	addr += ":"
	if len(argv) > 1 {
		addr += argv[1]
	} else {
		addr += "1337"
	}

	return addr
}

func setLogFile() {
	// Open file
	fd, err := os.OpenFile(logFile, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
	if err != nil {
		logger.Error(err.Error())
	}

	// Try close if old descriptor is defined.
	if logfd != nil {
		if err = logfd.Close(); err != nil {
			logger.Error(err.Error())
		}
	}

	// Update variable and set log writer.
	logfd = fd
	logger.SetHandler(log.StreamHandler(logfd, logfmt))
}

//	signalEventLoop()
//	  Initialize event channel for OS signals
//	  and runs an event loop.
//
// ---------------------------------------------------------
func signalEventLoop() {
	// Setup a channel
	sig_ch := make(chan os.Signal, 1)

	// subscribe to SIGHUP signal.
	signal.Notify(sig_ch, syscall.SIGHUP, syscall.SIGINT, syscall.SIGTERM)

	// Event loop
	var run bool = true
	for run {
		// Block until we get a signal.
		sig := <-sig_ch

		l := logger.New("signal", sig)

		switch sig {
		case syscall.SIGINT, syscall.SIGTERM:
			l.Info("Program was asked to terminate.")
			run = false

			// Tell the server to close.
			err := srv.Close()
			if err != nil {
				l.Error("Failed to close server", "error", err)
			}
		// SIGHUP is sent when logfile is rotated.
		case syscall.SIGHUP:
			msg := "Logfile was rotated: "

			if logfd != nil {
				setLogFile()
				msg += "Filedescriptor was updated"
			} else {
				msg += "No Filedescriptor to update (most likely uses standard out/err streams)"
			}

			l.Info(msg)
		default:
			l.Warn("Unknown signal")
		}
	}
}

//	main
//
// ---------------------------------------------------------
func main() {
	var version bool
	var usage bool
	var logFormatter *string
	// Set default timeout to 2 sec
	// as haproxy "inter" parameter to healthcheck is set to 2s per default.
	req_timeout := time.Second * 2

	logger = log.Root()

	// Command line parsing
	getopt.SetParameters("[ip] [port]")
	getopt.FlagLong(&usage, "help", 'h', "Print this help text")
	getopt.FlagLong(&version, "version", 'v', "Print version")
	getopt.FlagLong(&logFile, "log", 'l', "Path to log file", "file")
	getopt.FlagLong(&pidFile, "pid", 'p', "Path to pid file", "file")
	getopt.FlagLong(&req_timeout, "timeout", 't', "Set the maximum time before a request times out, valid prefixes are 's','ms','us'", "duration")
	logFormatter = getopt.EnumLong("log-format", 0, []string{"term", "logfmt", "json", "json-pretty"}, "", "Log format to use: term,logfmt,json,json-pretty")

	getopt.Parse()

	if usage {
		getopt.Usage()
		return
	}

	if version {
		fmt.Printf("Version: %s\n", VersionString)
		return
	}

	logfmt = utils.ParseLogFormatter(*logFormatter)

	// Open logfile.
	if len(logFile) > 0 {
		setLogFile()
	} else {
		logger.SetHandler(log.StreamHandler(os.Stdout, logfmt))
	}

	logger.Info("Process is starting", "pid", pid.Get())

	if len(pidFile) > 0 {
		logger.Info("Writing pidfile", "file", pidFile)
		err := pid.Save(pidFile)
		if err != nil {
			logger.Error("Failed to write pidfile", "msg", err)
		}
	}

	if req_timeout.Seconds() < 2 {
		// Dont alow anything below 2 seconds. that is abit aggressive.
		logger.Warn("Request timeout is less than the minimum. Setting it to 2 seconds", "req_timeout", req_timeout)
		req_timeout = time.Second * 2
	} else if req_timeout.Minutes() > 1.0 {
		// Anything more than 1 min is too long :)
		logger.Warn("Request timeout is more than the maximum. Setting it to 1 minute", "req_timeout", req_timeout)
		req_timeout = time.Minute
	}

	// Create server
	srv = server.New(argv_listen_addr(), server.WithTick(time.Second*10), server.WithTimeout(req_timeout))

	// Run signal event loop in its own goroutine
	go signalEventLoop()

	// Run server
	if err := srv.Run(); err != nil {
		logger.Error("Server error", "error", err)
		os.Exit(1)
	}
}