init.go

package main

import (
	"log"
	"os"
	"runtime"
	"runtime/debug"
	"strings"

	"github.com/eBay/fabio/config"
	"github.com/eBay/fabio/metrics"
	"github.com/eBay/fabio/registry"
	"github.com/eBay/fabio/registry/consul"
	"github.com/eBay/fabio/route"
)

func loadConfig(filename string) *config.Config {
	cfg, err := config.FromFile(filename)
	if err != nil {
		log.Fatal("[FATAL] ", err)
	}
	return cfg
}

func initBackend(cfg *config.Config) {
	var err error
	registry.Default, err = consul.NewBackend(&cfg.Consul, cfg.UI.Addr)
	if err != nil {
		log.Fatal("[FATAL] Error initializing backend. ", err)
	}
	if err := registry.Default.Register(); err != nil {
		log.Fatal("[FATAL] Error registering backend. ", err)
	}
}

func initMetrics(cfg *config.Config) {
	if err := metrics.Init(cfg.Metrics); err != nil {
		log.Fatal("[FATAL] ", err)
	}
}

func initRuntime(cfg *config.Config) {
	if os.Getenv("GOGC") == "" {
		log.Print("[INFO] Setting GOGC=", cfg.Runtime.GOGC)
		debug.SetGCPercent(cfg.Runtime.GOGC)
	} else {
		log.Print("[INFO] Using GOGC=", os.Getenv("GOGC"), " from env")
	}

	if os.Getenv("GOMAXPROCS") == "" {
		log.Print("[INFO] Setting GOMAXPROCS=", cfg.Runtime.GOMAXPROCS)
		runtime.GOMAXPROCS(cfg.Runtime.GOMAXPROCS)
	} else {
		log.Print("[INFO] Using GOMAXPROCS=", os.Getenv("GOMAXPROCS"), " from env")
	}
}

func initRoutes(cfg *config.Config) {
	if cfg.Routes == "" {
		initDynamicRoutes()
	} else {
		initStaticRoutes(cfg.Routes)
	}
}

// initDynamicRoutes watches the registry for changes in service
// registration/health and manual overrides and merge them into a new routing
// table
func initDynamicRoutes() {
	go func() {
		var (
			last   string
			svccfg string
			mancfg string
		)

		svc := registry.Default.WatchServices()
		man := registry.Default.WatchManual()

		for {
			select {
			case svccfg = <-svc:
			case mancfg = <-man:
			}

			// manual config overrides service config
			// order matters
			next := svccfg + "\n" + mancfg
			if next == last {
				continue
			}

			t, err := route.ParseString(next)
			if err != nil {
				log.Printf("[WARN] %s", err)
				continue
			}
			route.SetTable(t)

			last = next
		}
	}()
}

func initStaticRoutes(routes string) {
	var err error
	var t route.Table

	if strings.HasPrefix(routes, "@") {
		routes = routes[1:]
		log.Print("[INFO] Using static routes from ", routes)
		t, err = route.ParseFile(routes)
	} else {
		log.Print("[INFO] Using static routes from config file")
		t, err = route.ParseString(routes)
	}

	if err != nil {
		log.Fatal("[FATAL] ", err)
	}

	route.SetTable(t)
}