Dynamic Configuration Refactoring

server/service/service.go

@@ -0,0 +1,280 @@
+package service
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"time"
+
+	"github.com/containous/flaeg/parse"
+	"github.com/containous/traefik/config"
+	"github.com/containous/traefik/healthcheck"
+	"github.com/containous/traefik/log"
+	"github.com/containous/traefik/middlewares/emptybackendhandler"
+	"github.com/containous/traefik/old/middlewares/pipelining"
+	"github.com/containous/traefik/server/cookie"
+	"github.com/vulcand/oxy/forward"
+	"github.com/vulcand/oxy/roundrobin"
+)
+
+const (
+	defaultHealthCheckInterval = 30 * time.Second
+	defaultHealthCheckTimeout  = 5 * time.Second
+)
+
+// See oxy/roundrobin/rr.go
+type balancerHandler interface {
+	Servers() []*url.URL
+	ServeHTTP(w http.ResponseWriter, req *http.Request)
+	ServerWeight(u *url.URL) (int, bool)
+	RemoveServer(u *url.URL) error
+	UpsertServer(u *url.URL, options ...roundrobin.ServerOption) error
+	NextServer() (*url.URL, error)
+	Next() http.Handler
+}
+
+// NewManager creates a new Manager
+func NewManager(configs map[string]*config.Service, defaultRoundTripper http.RoundTripper) *Manager {
+	return &Manager{
+		bufferPool:          newBufferPool(),
+		defaultRoundTripper: defaultRoundTripper,
+		balancers:           make(map[string][]healthcheck.BalancerHandler),
+		configs:             configs,
+	}
+}
+
+// Manager The service manager
+type Manager struct {
+	bufferPool          httputil.BufferPool
+	defaultRoundTripper http.RoundTripper
+	balancers           map[string][]healthcheck.BalancerHandler
+	configs             map[string]*config.Service
+}
+
+// Build Creates a http.Handler for a service configuration.
+func (m *Manager) Build(rootCtx context.Context, serviceName string, responseModifier func(*http.Response) error) (http.Handler, error) {
+	ctx := log.With(rootCtx, log.Str(log.ServiceName, serviceName))
+
+	// TODO refactor ?
+	if conf, ok := m.configs[serviceName]; ok {
+		// FIXME Should handle multiple service types
+		return m.getLoadBalancerServiceHandler(ctx, serviceName, conf.LoadBalancer, responseModifier)
+	}
+	return nil, fmt.Errorf("the service %q does not exits", serviceName)
+}
+
+func (m *Manager) getLoadBalancerServiceHandler(
+	ctx context.Context,
+	serviceName string,
+	service *config.LoadBalancerService,
+	responseModifier func(*http.Response) error,
+) (http.Handler, error) {
+
+	fwd, err := m.buildForwarder(service.PassHostHeader, service.ResponseForwarding, responseModifier)
+	if err != nil {
+		return nil, err
+	}
+
+	fwd = pipelining.NewPipelining(fwd)
+
+	rr, err := roundrobin.New(fwd)
+	if err != nil {
+		return nil, err
+	}
+
+	balancer, err := m.getLoadBalancer(ctx, serviceName, service, fwd, rr)
+	if err != nil {
+		return nil, err
+	}
+
+	// TODO rename and checks
+	m.balancers[serviceName] = append(m.balancers[serviceName], balancer)
+
+	// Empty (backend with no servers)
+	return emptybackendhandler.New(balancer), nil
+}
+
+// LaunchHealthCheck Launches the health checks.
+func (m *Manager) LaunchHealthCheck() {
+	backendConfigs := make(map[string]*healthcheck.BackendConfig)
+
+	for serviceName, balancers := range m.balancers {
+		ctx := log.With(context.Background(), log.Str(log.ServiceName, serviceName))
+
+		// FIXME aggregate
+		balancer := balancers[0]
+
+		// FIXME Should all the services handle healthcheck? Handle different types
+		service := m.configs[serviceName].LoadBalancer
+
+		// Health Check
+		var backendHealthCheck *healthcheck.BackendConfig
+		if hcOpts := buildHealthCheckOptions(ctx, balancer, serviceName, service.HealthCheck); hcOpts != nil {
+			log.FromContext(ctx).Debugf("Setting up healthcheck for service %s with %s", serviceName, *hcOpts)
+
+			hcOpts.Transport = m.defaultRoundTripper
+			backendHealthCheck = healthcheck.NewBackendConfig(*hcOpts, serviceName)
+		}
+
+		if backendHealthCheck != nil {
+			backendConfigs[serviceName] = backendHealthCheck
+		}
+	}
+
+	// FIXME metrics and context
+	healthcheck.GetHealthCheck().SetBackendsConfiguration(context.TODO(), backendConfigs)
+}
+
+func buildHealthCheckOptions(ctx context.Context, lb healthcheck.BalancerHandler, backend string, hc *config.HealthCheck) *healthcheck.Options {
+	if hc == nil || hc.Path == "" {
+		return nil
+	}
+
+	logger := log.FromContext(ctx)
+
+	interval := defaultHealthCheckInterval
+	if hc.Interval != "" {
+		intervalOverride, err := time.ParseDuration(hc.Interval)
+		if err != nil {
+			logger.Errorf("Illegal health check interval for '%s': %s", backend, err)
+		} else if intervalOverride <= 0 {
+			logger.Errorf("Health check interval smaller than zero for service '%s'", backend)
+		} else {
+			interval = intervalOverride
+		}
+	}
+
+	timeout := defaultHealthCheckTimeout
+	if hc.Timeout != "" {
+		timeoutOverride, err := time.ParseDuration(hc.Timeout)
+		if err != nil {
+			logger.Errorf("Illegal health check timeout for backend '%s': %s", backend, err)
+		} else if timeoutOverride <= 0 {
+			logger.Errorf("Health check timeout smaller than zero for backend '%s', backend", backend)
+		} else {
+			timeout = timeoutOverride
+		}
+	}
+
+	if timeout >= interval {
+		logger.Warnf("Health check timeout for backend '%s' should be lower than the health check interval. Interval set to timeout + 1 second (%s).", backend)
+	}
+
+	return &healthcheck.Options{
+		Scheme:   hc.Scheme,
+		Path:     hc.Path,
+		Port:     hc.Port,
+		Interval: interval,
+		Timeout:  timeout,
+		LB:       lb,
+		Hostname: hc.Hostname,
+		Headers:  hc.Headers,
+	}
+}
+
+func (m *Manager) getLoadBalancer(ctx context.Context, serviceName string, service *config.LoadBalancerService, fwd http.Handler, rr balancerHandler) (healthcheck.BalancerHandler, error) {
+	logger := log.FromContext(ctx)
+
+	var stickySession *roundrobin.StickySession
+	var cookieName string
+	if stickiness := service.Stickiness; stickiness != nil {
+		cookieName = cookie.GetName(stickiness.CookieName, serviceName)
+		stickySession = roundrobin.NewStickySession(cookieName)
+	}
+
+	var lb healthcheck.BalancerHandler
+	var err error
+
+	if service.Method == "drr" {
+		logger.Debug("Creating drr load-balancer")
+
+		if stickySession != nil {
+			logger.Debugf("Sticky session cookie name: %v", cookieName)
+
+			lb, err = roundrobin.NewRebalancer(rr, roundrobin.RebalancerStickySession(stickySession))
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			lb, err = roundrobin.NewRebalancer(rr)
+			if err != nil {
+				return nil, err
+			}
+		}
+	} else {
+		if service.Method != "wrr" {
+			logger.Warnf("Invalid load-balancing method %q, fallback to 'wrr' method", service.Method)
+		}
+
+		logger.Debug("Creating wrr load-balancer")
+
+		if stickySession != nil {
+			logger.Debugf("Sticky session cookie name: %v", cookieName)
+
+			lb, err = roundrobin.New(fwd, roundrobin.EnableStickySession(stickySession))
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			lb = rr
+		}
+	}
+
+	if err := m.upsertServers(ctx, lb, service.Servers); err != nil {
+		return nil, fmt.Errorf("error configuring load balancer for service %s: %v", serviceName, err)
+	}
+
+	return lb, nil
+}
+
+func (m *Manager) upsertServers(ctx context.Context, lb healthcheck.BalancerHandler, servers []config.Server) error {
+	logger := log.FromContext(ctx)
+
+	for name, srv := range servers {
+		u, err := url.Parse(srv.URL)
+		if err != nil {
+			return fmt.Errorf("error parsing server URL %s: %v", srv.URL, err)
+		}
+
+		logger.WithField(log.ServerName, name).Debugf("Creating server %d at %s with weight %d", name, u, srv.Weight)
+
+		if err := lb.UpsertServer(u, roundrobin.Weight(srv.Weight)); err != nil {
+			return fmt.Errorf("error adding server %s to load balancer: %v", srv.URL, err)
+		}
+
+		// FIXME Handle Metrics
+	}
+	return nil
+}
+
+func (m *Manager) buildForwarder(passHostHeader bool, responseForwarding *config.ResponseForwarding, responseModifier func(*http.Response) error) (http.Handler, error) {
+
+	var flushInterval parse.Duration
+	if responseForwarding != nil {
+		err := flushInterval.Set(responseForwarding.FlushInterval)
+		if err != nil {
+			return nil, fmt.Errorf("error creating flush interval: %v", err)
+		}
+	}
+
+	return forward.New(
+		forward.Stream(true),
+		forward.PassHostHeader(passHostHeader),
+		forward.RoundTripper(m.defaultRoundTripper),
+		forward.ResponseModifier(responseModifier),
+		forward.BufferPool(m.bufferPool),
+		forward.StreamingFlushInterval(time.Duration(flushInterval)),
+		forward.WebsocketConnectionClosedHook(func(req *http.Request, conn net.Conn) {
+			server := req.Context().Value(http.ServerContextKey).(*http.Server)
+			if server != nil {
+				connState := server.ConnState
+				if connState != nil {
+					connState(conn, http.StateClosed)
+				}
+			}
+		}),
+	)
+}