main.go

// Copyright 2023 LY Corporation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"context"
	"flag"
	"os"
	"os/signal"
	"path/filepath"
	"runtime"
	"syscall"

	"github.com/AthenZ/athenz-client-sidecar/v2/config"
	"github.com/AthenZ/athenz-client-sidecar/v2/usecase"
	"github.com/kpango/glg"
	"github.com/pkg/errors"
)

// Version is set by the build command via LDFLAGS
var Version string

type params struct {
	configFilePath string
	showVersion    bool
}

func parseParams() (*params, error) {
	p := new(params)
	f := flag.NewFlagSet(filepath.Base(os.Args[0]), flag.ContinueOnError)
	f.StringVar(&p.configFilePath,
		"f",
		"/etc/athenz/client/config.yaml",
		"client config yaml file path")
	f.BoolVar(&p.showVersion,
		"version",
		false,
		"show athenz-client-sidecar version")

	err := f.Parse(os.Args[1:])
	if err != nil {
		return nil, errors.Wrap(err, "Parse Failed")
	}

	return p, nil
}

func run(cfg config.Config) []error {
	g := glg.Get().SetMode(glg.NONE)

	switch cfg.Log.Level {
	case "":
		// disable logging
	case "fatal":
		g = g.SetLevelMode(glg.FATAL, glg.STD)
	case "error":
		g = g.SetLevelMode(glg.FATAL, glg.STD).
			SetLevelMode(glg.ERR, glg.STD)
	case "warn":
		g = g.SetLevelMode(glg.FATAL, glg.STD).
			SetLevelMode(glg.ERR, glg.STD).
			SetLevelMode(glg.WARN, glg.STD)
	case "info":
		g = g.SetLevelMode(glg.FATAL, glg.STD).
			SetLevelMode(glg.ERR, glg.STD).
			SetLevelMode(glg.WARN, glg.STD).
			SetLevelMode(glg.INFO, glg.STD)
	case "debug":
		g = g.SetLevelMode(glg.FATAL, glg.STD).
			SetLevelMode(glg.ERR, glg.STD).
			SetLevelMode(glg.WARN, glg.STD).
			SetLevelMode(glg.INFO, glg.STD).
			SetLevelMode(glg.DEBG, glg.STD)
	default:
		return []error{errors.New("invalid log level")}
	}

	if !cfg.Log.Color {
		g.DisableColor()
	}

	daemon, err := usecase.New(cfg)
	if err != nil {
		return []error{errors.Wrap(err, "tenant error")}
	}

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	ech := daemon.Start(ctx)

	sigCh := make(chan os.Signal, 1)
	signal.Notify(sigCh, syscall.SIGTERM, syscall.SIGINT)

	isSignal := false
	for {
		select {
		case sig := <-sigCh:
			glg.Infof("Athenz client sidecar received signal: %v", sig)
			isSignal = true
			cancel()
			glg.Warn("Athenz client sidecar shutdown...")
		case errs := <-ech:
			if !isSignal || len(errs) != 1 || errs[0] != ctx.Err() {
				return errs
			}
			return nil
		}
	}
}

func main() {
	defer func() {
		if err := recover(); err != nil {
			if _, ok := err.(runtime.Error); ok {
				panic(err)
			}
			glg.Error(err)
		}
	}()

	p, err := parseParams()
	if err != nil {
		glg.Fatal(err)
		return
	}

	if p.showVersion {
		err := glg.Infof("athenz-client-sidecar version -> %s", getVersion())
		if err != nil {
			glg.Fatal(err)
		}
		err = glg.Infof("athenz-client-sidecar config version -> %s", config.GetVersion())
		if err != nil {
			glg.Fatal(err)
		}
		return
	}

	cfg, err := config.New(p.configFilePath)
	if err != nil {
		glg.Fatal(err)
		return
	}

	if cfg.Version != config.GetVersion() {
		glg.Fatal(errors.New("invalid Athenz client proxy configuration version"))
		return
	}

	errs := run(*cfg)
	if len(errs) > 0 {
		glg.Fatalf("%+v", errs)
		return
	}
	glg.Info("Athenz client sidecar shutdown success")

	/*
		For some reason, if only Sidecar has terminated while the main application continues to run,
		the exit status is set to 1 to prevent the main application from continuing to operate alone.
		During the development of Sidecar, we found a pattern where even if some containers within a Pod in Kubernetes exit with status 0,
		the Pod as a whole continues to operate.
		By setting the exit status of Sidecar to 1,
		it is expected that the entire Pod will be restarted from the Kubernetes side under any circumstances.
	*/
	os.Exit(1)
}

func getVersion() string {
	if Version == "" {
		return "development version"
	}
	return Version
}