opencloud/pkg/command/server.go

package command

import (
	"context"
	gohttp "net/http"
	"net/http/httputil"
	"net/url"
	"os"
	"os/signal"
	"strings"
	"time"

	"contrib.go.opencensus.io/exporter/jaeger"
	"contrib.go.opencensus.io/exporter/ocagent"
	"contrib.go.opencensus.io/exporter/zipkin"
	"github.com/micro/cli/v2"
	"github.com/oklog/run"
	openzipkin "github.com/openzipkin/zipkin-go"
	zipkinhttp "github.com/openzipkin/zipkin-go/reporter/http"
	"github.com/owncloud/ocis-pkg/v2/log"
	"github.com/owncloud/ocis-proxy/pkg/config"
	"github.com/owncloud/ocis-proxy/pkg/flagset"
	"github.com/owncloud/ocis-proxy/pkg/metrics"
	"github.com/owncloud/ocis-proxy/pkg/server/debug"
	"github.com/owncloud/ocis-proxy/pkg/server/http"
	"go.opencensus.io/stats/view"
	"go.opencensus.io/trace"
)

// ReverseProxy extends httputil to support multiple hosts with diffent policies
type ReverseProxy struct {
	httputil.ReverseProxy
	Directors map[string]map[string]func(req *gohttp.Request)
}

// Server is the entrypoint for the server command.
func Server(cfg *config.Config) *cli.Command {
	return &cli.Command{
		Name:  "server",
		Usage: "Start integrated server",
		Flags: flagset.ServerWithConfig(cfg),
		Before: func(c *cli.Context) error {
			if cfg.HTTP.Root != "/" {
				cfg.HTTP.Root = strings.TrimSuffix(cfg.HTTP.Root, "/")
			}

			return nil
		},
		Action: func(c *cli.Context) error {
			logger := log.NewLogger()
			httpNamespace := c.String("http-namespace")

			if cfg.Tracing.Enabled {
				switch t := cfg.Tracing.Type; t {
				case "agent":
					exporter, err := ocagent.NewExporter(
						ocagent.WithReconnectionPeriod(5*time.Second),
						ocagent.WithAddress(cfg.Tracing.Endpoint),
						ocagent.WithServiceName(cfg.Tracing.Service),
					)

					if err != nil {
						logger.Error().
							Err(err).
							Str("endpoint", cfg.Tracing.Endpoint).
							Str("collector", cfg.Tracing.Collector).
							Msg("Failed to create agent tracing")

						return err
					}

					trace.RegisterExporter(exporter)
					view.RegisterExporter(exporter)

				case "jaeger":
					exporter, err := jaeger.NewExporter(
						jaeger.Options{
							AgentEndpoint:     cfg.Tracing.Endpoint,
							CollectorEndpoint: cfg.Tracing.Collector,
							ServiceName:       cfg.Tracing.Service,
						},
					)

					if err != nil {
						logger.Error().
							Err(err).
							Str("endpoint", cfg.Tracing.Endpoint).
							Str("collector", cfg.Tracing.Collector).
							Msg("Failed to create jaeger tracing")

						return err
					}

					trace.RegisterExporter(exporter)

				case "zipkin":
					endpoint, err := openzipkin.NewEndpoint(
						cfg.Tracing.Service,
						cfg.Tracing.Endpoint,
					)

					if err != nil {
						logger.Error().
							Err(err).
							Str("endpoint", cfg.Tracing.Endpoint).
							Str("collector", cfg.Tracing.Collector).
							Msg("Failed to create zipkin tracing")

						return err
					}

					exporter := zipkin.NewExporter(
						zipkinhttp.NewReporter(
							cfg.Tracing.Collector,
						),
						endpoint,
					)

					trace.RegisterExporter(exporter)

				default:
					logger.Warn().
						Str("type", t).
						Msg("Unknown tracing backend")
				}

				trace.ApplyConfig(
					trace.Config{
						DefaultSampler: trace.AlwaysSample(),
					},
				)
			} else {
				logger.Debug().
					Msg("Tracing is not enabled")
			}

			var (
				gr          = run.Group{}
				ctx, cancel = context.WithCancel(context.Background())
				metrics     = metrics.New()
			)

			defer cancel()

			rp := NewMultiHostReverseProxy(cfg)

			{
				server, err := http.Server(
					http.Handler(rp),
					http.Logger(logger),
					http.Namespace(httpNamespace),
					http.Context(ctx),
					http.Config(cfg),
					http.Metrics(metrics),
					http.Flags(flagset.RootWithConfig(cfg)),
					http.Flags(flagset.ServerWithConfig(cfg)),
				)

				if err != nil {
					logger.Error().
						Err(err).
						Str("server", "http").
						Msg("Failed to initialize server")

					return err
				}

				gr.Add(func() error {
					return server.Run()
				}, func(_ error) {
					logger.Info().
						Str("server", "http").
						Msg("Shutting down server")

					cancel()
				})
			}

			{
				server, err := debug.Server(
					debug.Logger(logger),
					debug.Context(ctx),
					debug.Config(cfg),
				)

				if err != nil {
					logger.Error().
						Err(err).
						Str("server", "debug").
						Msg("Failed to initialize server")

					return err
				}

				gr.Add(func() error {
					return server.ListenAndServe()
				}, func(_ error) {
					ctx, timeout := context.WithTimeout(ctx, 5*time.Second)

					defer timeout()
					defer cancel()

					if err := server.Shutdown(ctx); err != nil {
						logger.Error().
							Err(err).
							Str("server", "debug").
							Msg("Failed to shutdown server")
					} else {
						logger.Info().
							Str("server", "debug").
							Msg("Shutting down server")
					}
				})
			}

			{
				stop := make(chan os.Signal, 1)

				gr.Add(func() error {
					signal.Notify(stop, os.Interrupt)

					<-stop

					return nil
				}, func(err error) {
					close(stop)
					cancel()
				})
			}

			return gr.Run()
		},
	}
}

// NewMultiHostReverseProxy undocummented
func NewMultiHostReverseProxy(conf *config.Config) *ReverseProxy {
	reverseProxy := &ReverseProxy{Directors: make(map[string]map[string]func(req *gohttp.Request))}

	for _, policy := range conf.Policies {
		for _, route := range policy.Routes {
			uri, err := url.Parse(route.Backend)
			if err != nil { /* do something with err */
			}
			reverseProxy.AddHost(policy.Name, uri, route.Endpoint)
		}
	}

	return reverseProxy
}

func singleJoiningSlash(a, b string) string {
	aslash := strings.HasSuffix(a, "/")
	bslash := strings.HasPrefix(b, "/")
	switch {
	case aslash && bslash:
		return a + b[1:]
	case !aslash && !bslash:
		return a + "/" + b
	}
	return a + b
}

// AddHost undocumented
func (p *ReverseProxy) AddHost(policy string, target *url.URL, endpoint string) {
	targetQuery := target.RawQuery
	if p.Directors[policy] == nil {
		p.Directors[policy] = make(map[string]func(req *gohttp.Request))
	}
	p.Directors[policy][endpoint] = func(req *gohttp.Request) {
		req.URL.Scheme = target.Scheme
		req.URL.Host = target.Host
		req.URL.Path = singleJoiningSlash(target.Path, req.URL.Path)
		if targetQuery == "" || req.URL.RawQuery == "" {
			req.URL.RawQuery = targetQuery + req.URL.RawQuery
		} else {
			req.URL.RawQuery = targetQuery + "&" + req.URL.RawQuery
		}
		if _, ok := req.Header["User-Agent"]; !ok {
			// explicitly disable User-Agent so it's not set to default value
			req.Header.Set("User-Agent", "")
		}
	}
}

func (p *ReverseProxy) ServeHTTP(rw gohttp.ResponseWriter, req *gohttp.Request) {
	// TODO need to fetch from the accounts service
	policy := "reva"
	var hit bool

	for k := range p.Directors[policy] {
		if strings.HasPrefix(req.URL.Path, k) && k != "/" {
			p.Director = p.Directors[policy][k]
			hit = true
		}
	}

	// override default director with root. If any
	if !hit && p.Directors[policy]["/"] != nil {
		p.Director = p.Directors[policy]["/"]
	}

	// Call upstream ServeHTTP
	p.ReverseProxy.ServeHTTP(rw, req)
}