config.go

package main

import (
	"os"
	"strings"

	log "github.com/sirupsen/logrus"
)

type Config struct {
	LoggingEnabled          bool
	EnvoyAdminAPI           string
	StartWithoutEnvoy       bool
	IstioQuitAPI            string
	NeverKillIstio          bool
	IstioFallbackPkill      bool
	NeverKillIstioOnFailure bool
	GenericQuitEndpoints    []string
}

func getConfig() Config {
	loggingEnabled := getBoolFromEnv("ENVOY_PREFLIGHT_LOGGING", true, false)

	if getStringFromEnv("ENVOY_KILL_API", "", false) != "" {
		log.Error("don't use ENVOY_KILL_API but ISTIO_QUIT_API instead")
	}

	defaultEnvoyAdminAPI := ""
	defaultIstioQuitAPI := ""

	if getBoolFromEnv("USE_ISTIO_ENDPOINT", false, loggingEnabled) {
		defaultEnvoyAdminAPI = "http://127.0.0.1:15000"
		defaultIstioQuitAPI = "http://127.0.0.1:15020"
	}

	config := Config{
		// Logging enabled by default, disabled if "false"
		LoggingEnabled:          loggingEnabled,
		EnvoyAdminAPI:           getStringFromEnv("ENVOY_ADMIN_API", defaultEnvoyAdminAPI, loggingEnabled),
		StartWithoutEnvoy:       getBoolFromEnv("START_WITHOUT_ENVOY", false, loggingEnabled),
		IstioQuitAPI:            getStringFromEnv("ISTIO_QUIT_API", defaultIstioQuitAPI, loggingEnabled),
		NeverKillIstio:          getBoolFromEnv("NEVER_KILL_ISTIO", false, loggingEnabled),
		IstioFallbackPkill:      getBoolFromEnv("ISTIO_FALLBACK_PKILL", false, loggingEnabled),
		NeverKillIstioOnFailure: getBoolFromEnv("NEVER_KILL_ISTIO_ON_FAILURE", false, loggingEnabled),
		GenericQuitEndpoints:    getStringArrayFromEnv("GENERIC_QUIT_ENDPOINTS", make([]string, 0), loggingEnabled),
	}

	return config
}

func getStringArrayFromEnv(name string, defaultVal []string, logEnabled bool) []string {
	userValCsv := strings.Trim(os.Getenv(name), " ")

	if userValCsv == "" {
		return defaultVal
	}

	if logEnabled {
		log.Infof("%s: %s", name, userValCsv)
	}

	userValArray := strings.Split(userValCsv, ",")
	if len(userValArray) == 0 {
		return defaultVal
	}

	return userValArray
}

func getStringFromEnv(name string, defaultVal string, logEnabled bool) string {
	userVal := os.Getenv(name)
	if logEnabled {
		log.Infof("%s: %s", name, userVal)
	}
	if userVal != "" {
		return userVal
	}
	return defaultVal
}

func getBoolFromEnv(name string, defaultVal bool, logEnabled bool) bool {
	userVal := os.Getenv(name)
	// User did not set anything return default
	if userVal == "" {
		return defaultVal
	}

	// User set something, check it is valid
	if userVal != "true" && userVal != "false" {
		if logEnabled {
			log.Infof("%s: %s (Invalid value will be ignored)", name, userVal)
		}
		return defaultVal
	}

	// User gave valid option
	if logEnabled {
		log.Infof("%s: %s", name, userVal)
	}
	return (userVal == "true")
}