traefik/pkg/server/router/router.go
Simon Delicata d6598f370c
Multi-layer routing
Co-authored-by: Romain <rtribotte@users.noreply.github.com>
2025-10-22 11:58:05 +02:00

495 lines
16 KiB
Go

package router
import (
"context"
"errors"
"fmt"
"math"
"net/http"
"slices"
"sort"
"strings"
"github.com/containous/alice"
"github.com/rs/zerolog/log"
"github.com/traefik/traefik/v3/pkg/config/dynamic"
"github.com/traefik/traefik/v3/pkg/config/runtime"
"github.com/traefik/traefik/v3/pkg/middlewares/accesslog"
"github.com/traefik/traefik/v3/pkg/middlewares/denyrouterrecursion"
metricsMiddle "github.com/traefik/traefik/v3/pkg/middlewares/metrics"
"github.com/traefik/traefik/v3/pkg/middlewares/observability"
"github.com/traefik/traefik/v3/pkg/middlewares/recovery"
httpmuxer "github.com/traefik/traefik/v3/pkg/muxer/http"
"github.com/traefik/traefik/v3/pkg/observability/logs"
"github.com/traefik/traefik/v3/pkg/server/middleware"
"github.com/traefik/traefik/v3/pkg/server/provider"
"github.com/traefik/traefik/v3/pkg/tls"
)
const maxUserPriority = math.MaxInt - 1000
type middlewareBuilder interface {
BuildChain(ctx context.Context, names []string) *alice.Chain
}
type serviceManager interface {
BuildHTTP(rootCtx context.Context, serviceName string) (http.Handler, error)
LaunchHealthCheck(ctx context.Context)
}
// Manager A route/router manager.
type Manager struct {
routerHandlers map[string]http.Handler
serviceManager serviceManager
observabilityMgr *middleware.ObservabilityMgr
middlewaresBuilder middlewareBuilder
conf *runtime.Configuration
tlsManager *tls.Manager
parser httpmuxer.SyntaxParser
}
// NewManager creates a new Manager.
func NewManager(conf *runtime.Configuration, serviceManager serviceManager, middlewaresBuilder middlewareBuilder, observabilityMgr *middleware.ObservabilityMgr, tlsManager *tls.Manager, parser httpmuxer.SyntaxParser) *Manager {
return &Manager{
routerHandlers: make(map[string]http.Handler),
serviceManager: serviceManager,
observabilityMgr: observabilityMgr,
middlewaresBuilder: middlewaresBuilder,
conf: conf,
tlsManager: tlsManager,
parser: parser,
}
}
func (m *Manager) getHTTPRouters(ctx context.Context, entryPoints []string, tls bool) map[string]map[string]*runtime.RouterInfo {
if m.conf != nil {
return m.conf.GetRoutersByEntryPoints(ctx, entryPoints, tls)
}
return make(map[string]map[string]*runtime.RouterInfo)
}
// BuildHandlers Builds handler for all entry points.
func (m *Manager) BuildHandlers(rootCtx context.Context, entryPoints []string, tls bool) map[string]http.Handler {
entryPointHandlers := make(map[string]http.Handler)
defaultObsConfig := dynamic.RouterObservabilityConfig{}
defaultObsConfig.SetDefaults()
for entryPointName, routers := range m.getHTTPRouters(rootCtx, entryPoints, tls) {
logger := log.Ctx(rootCtx).With().Str(logs.EntryPointName, entryPointName).Logger()
ctx := logger.WithContext(rootCtx)
// TODO: Improve this part. Relying on models is a shortcut to get the entrypoint observability configuration. Maybe we should pass down the static configuration.
// When the entry point has no observability configuration no model is produced,
// and we need to create the default configuration is this case.
epObsConfig := defaultObsConfig
if model, ok := m.conf.Models[entryPointName+"@internal"]; ok && model != nil {
epObsConfig = model.Observability
}
handler, err := m.buildEntryPointHandler(ctx, entryPointName, routers, epObsConfig)
if err != nil {
logger.Error().Err(err).Send()
continue
}
entryPointHandlers[entryPointName] = handler
}
// Create default handlers.
for _, entryPointName := range entryPoints {
logger := log.Ctx(rootCtx).With().Str(logs.EntryPointName, entryPointName).Logger()
ctx := logger.WithContext(rootCtx)
handler, ok := entryPointHandlers[entryPointName]
if ok || handler != nil {
continue
}
// TODO: Improve this part. Relying on models is a shortcut to get the entrypoint observability configuration. Maybe we should pass down the static configuration.
// When the entry point has no observability configuration no model is produced,
// and we need to create the default configuration is this case.
epObsConfig := defaultObsConfig
if model, ok := m.conf.Models[entryPointName+"@internal"]; ok && model != nil {
epObsConfig = model.Observability
}
defaultHandler, err := m.observabilityMgr.BuildEPChain(ctx, entryPointName, false, epObsConfig).Then(http.NotFoundHandler())
if err != nil {
logger.Error().Err(err).Send()
continue
}
entryPointHandlers[entryPointName] = defaultHandler
}
return entryPointHandlers
}
func (m *Manager) buildEntryPointHandler(ctx context.Context, entryPointName string, configs map[string]*runtime.RouterInfo, config dynamic.RouterObservabilityConfig) (http.Handler, error) {
muxer := httpmuxer.NewMuxer(m.parser)
defaultHandler, err := m.observabilityMgr.BuildEPChain(ctx, entryPointName, false, config).Then(http.NotFoundHandler())
if err != nil {
return nil, err
}
muxer.SetDefaultHandler(defaultHandler)
for routerName, routerConfig := range configs {
logger := log.Ctx(ctx).With().Str(logs.RouterName, routerName).Logger()
ctxRouter := logger.WithContext(provider.AddInContext(ctx, routerName))
if routerConfig.Priority == 0 {
routerConfig.Priority = httpmuxer.GetRulePriority(routerConfig.Rule)
}
if routerConfig.Priority > maxUserPriority && !strings.HasSuffix(routerName, "@internal") {
err = fmt.Errorf("the router priority %d exceeds the max user-defined priority %d", routerConfig.Priority, maxUserPriority)
routerConfig.AddError(err, true)
logger.Error().Err(err).Send()
continue
}
// Only build handlers for root routers (routers without ParentRefs).
// Routers with ParentRefs will be built as part of their parent router's muxer.
if len(routerConfig.ParentRefs) > 0 {
continue
}
handler, err := m.buildRouterHandler(ctxRouter, routerName, routerConfig)
if err != nil {
routerConfig.AddError(err, true)
logger.Error().Err(err).Send()
continue
}
if routerConfig.Observability != nil {
config = *routerConfig.Observability
}
observabilityChain := m.observabilityMgr.BuildEPChain(ctxRouter, entryPointName, strings.HasSuffix(routerConfig.Service, "@internal"), config)
handler, err = observabilityChain.Then(handler)
if err != nil {
routerConfig.AddError(err, true)
logger.Error().Err(err).Send()
continue
}
if err = muxer.AddRoute(routerConfig.Rule, routerConfig.RuleSyntax, routerConfig.Priority, handler); err != nil {
routerConfig.AddError(err, true)
logger.Error().Err(err).Send()
continue
}
}
chain := alice.New()
chain = chain.Append(func(next http.Handler) (http.Handler, error) {
return recovery.New(ctx, next)
})
return chain.Then(muxer)
}
func (m *Manager) buildRouterHandler(ctx context.Context, routerName string, routerConfig *runtime.RouterInfo) (http.Handler, error) {
if handler, ok := m.routerHandlers[routerName]; ok {
return handler, nil
}
if routerConfig.TLS != nil {
// Don't build the router if the TLSOptions configuration is invalid.
tlsOptionsName := tls.DefaultTLSConfigName
if len(routerConfig.TLS.Options) > 0 && routerConfig.TLS.Options != tls.DefaultTLSConfigName {
tlsOptionsName = provider.GetQualifiedName(ctx, routerConfig.TLS.Options)
}
if _, err := m.tlsManager.Get(tls.DefaultTLSStoreName, tlsOptionsName); err != nil {
return nil, fmt.Errorf("building router handler: %w", err)
}
}
handler, err := m.buildHTTPHandler(ctx, routerConfig, routerName)
if err != nil {
return nil, err
}
m.routerHandlers[routerName] = handler
return m.routerHandlers[routerName], nil
}
func (m *Manager) buildHTTPHandler(ctx context.Context, router *runtime.RouterInfo, routerName string) (http.Handler, error) {
var qualifiedNames []string
for _, name := range router.Middlewares {
qualifiedNames = append(qualifiedNames, provider.GetQualifiedName(ctx, name))
}
router.Middlewares = qualifiedNames
chain := alice.New()
if router.DefaultRule {
chain = chain.Append(denyrouterrecursion.WrapHandler(routerName))
}
var (
nextHandler http.Handler
serviceName string
err error
)
// Check if this router has child routers or a service.
switch {
case len(router.ChildRefs) > 0:
// This router routes to child routers - create a muxer for them
nextHandler, err = m.buildChildRoutersMuxer(ctx, router.ChildRefs)
if err != nil {
return nil, fmt.Errorf("building child routers muxer: %w", err)
}
serviceName = fmt.Sprintf("%s-muxer", routerName)
case router.Service != "":
// This router routes to a service
qualifiedService := provider.GetQualifiedName(ctx, router.Service)
nextHandler, err = m.serviceManager.BuildHTTP(ctx, qualifiedService)
if err != nil {
return nil, err
}
serviceName = qualifiedService
default:
return nil, errors.New("router must have either a service or child routers")
}
// Access logs, metrics, and tracing middlewares are idempotent if the associated signal is disabled.
chain = chain.Append(observability.WrapRouterHandler(ctx, routerName, router.Rule, serviceName))
metricsHandler := metricsMiddle.RouterMetricsHandler(ctx, m.observabilityMgr.MetricsRegistry(), routerName, serviceName)
chain = chain.Append(observability.WrapMiddleware(ctx, metricsHandler))
chain = chain.Append(func(next http.Handler) (http.Handler, error) {
return accesslog.NewConcatFieldHandler(next, accesslog.RouterName, routerName), nil
})
mHandler := m.middlewaresBuilder.BuildChain(ctx, router.Middlewares)
return chain.Extend(*mHandler).Then(nextHandler)
}
// ParseRouterTree sets up router tree and validates router configuration.
// This function performs the following operations in order:
//
// 1. Populate ChildRefs: Uses ParentRefs to build the parent-child relationship graph
// 2. Root-first traversal: Starting from root routers (no ParentRefs), traverses the tree
// 3. Cycle detection: Detects circular dependencies and removes cyclic links
// 4. Reachability check: Marks routers unreachable from any root as disabled
// 5. Dead-end detection: Marks routers with no service and no children as disabled
// 6. Validation: Checks for configuration errors
//
// Router status is set during this process:
// - Enabled: Reachable routers with valid configuration
// - Disabled: Unreachable, dead-end, or routers with critical errors
// - Warning: Routers with non-critical errors (like cycles)
//
// The function modifies router.Status, router.ChildRefs, and adds errors to router.Err.
func (m *Manager) ParseRouterTree() {
if m.conf == nil || m.conf.Routers == nil {
return
}
// Populate ChildRefs based on ParentRefs and find root routers.
var rootRouters []string
for routerName, router := range m.conf.Routers {
if len(router.ParentRefs) == 0 {
rootRouters = append(rootRouters, routerName)
continue
}
for _, parentName := range router.ParentRefs {
if parentRouter, exists := m.conf.Routers[parentName]; exists {
// Add this router as a child of its parent
if !slices.Contains(parentRouter.ChildRefs, routerName) {
parentRouter.ChildRefs = append(parentRouter.ChildRefs, routerName)
}
} else {
router.AddError(fmt.Errorf("parent router %q does not exist", parentName), true)
}
}
// Check for non-root router with TLS config.
if router.TLS != nil {
router.AddError(errors.New("non-root router cannot have TLS configuration"), true)
continue
}
// Check for non-root router with Observability config.
if router.Observability != nil {
router.AddError(errors.New("non-root router cannot have Observability configuration"), true)
continue
}
// Check for non-root router with Entrypoint config.
if len(router.EntryPoints) > 0 {
router.AddError(errors.New("non-root router cannot have Entrypoints configuration"), true)
continue
}
}
sort.Strings(rootRouters)
// Root-first traversal with cycle detection.
visited := make(map[string]bool)
currentPath := make(map[string]bool)
var path []string
for _, rootName := range rootRouters {
if !visited[rootName] {
m.traverse(rootName, visited, currentPath, path)
}
}
for routerName, router := range m.conf.Routers {
// Set status for all routers based on reachability.
if !visited[routerName] {
router.AddError(errors.New("router is not reachable"), true)
continue
}
// Detect dead-end routers (no service + no children) - AFTER cycle handling.
if router.Service == "" && len(router.ChildRefs) == 0 {
router.AddError(errors.New("router has no service and no child routers"), true)
continue
}
// Check for router with service that is referenced as a parent.
if router.Service != "" && len(router.ChildRefs) > 0 {
router.AddError(errors.New("router has both a service and is referenced as a parent by other routers"), true)
continue
}
}
}
// traverse performs a depth-first traversal starting from root routers,
// detecting cycles and marking visited routers for reachability detection.
func (m *Manager) traverse(routerName string, visited, currentPath map[string]bool, path []string) {
if currentPath[routerName] {
// Found a cycle - handle it properly.
m.handleCycle(routerName, path)
return
}
if visited[routerName] {
return
}
router, exists := m.conf.Routers[routerName]
// Since the ChildRefs population already guarantees router existence, this check is purely defensive.
if !exists {
visited[routerName] = true
return
}
visited[routerName] = true
currentPath[routerName] = true
newPath := append(path, routerName)
// Sort ChildRefs for deterministic behavior.
sortedChildRefs := make([]string, len(router.ChildRefs))
copy(sortedChildRefs, router.ChildRefs)
sort.Strings(sortedChildRefs)
// Traverse children.
for _, childName := range sortedChildRefs {
m.traverse(childName, visited, currentPath, newPath)
}
currentPath[routerName] = false
}
// handleCycle handles cycle detection and removes the victim from guilty router's ChildRefs.
func (m *Manager) handleCycle(victimRouter string, path []string) {
// Find where the cycle starts in the path
cycleStart := -1
for i, name := range path {
if name == victimRouter {
cycleStart = i
break
}
}
if cycleStart < 0 {
return
}
// Build the cycle path: from cycle start to current + victim.
cyclePath := append(path[cycleStart:], victimRouter)
cycleRouters := strings.Join(cyclePath, " -> ")
// The guilty router is the last one in the path (the one creating the cycle).
if len(path) > 0 {
guiltyRouterName := path[len(path)-1]
guiltyRouter, exists := m.conf.Routers[guiltyRouterName]
if !exists {
return
}
// Add cycle error to guilty router.
guiltyRouter.AddError(fmt.Errorf("cyclic reference detected in router tree: %s", cycleRouters), false)
// Remove victim from guilty router's ChildRefs.
for i, childRef := range guiltyRouter.ChildRefs {
if childRef == victimRouter {
guiltyRouter.ChildRefs = append(guiltyRouter.ChildRefs[:i], guiltyRouter.ChildRefs[i+1:]...)
break
}
}
}
}
// buildChildRoutersMuxer creates a muxer for child routers.
func (m *Manager) buildChildRoutersMuxer(ctx context.Context, childRefs []string) (http.Handler, error) {
childMuxer := httpmuxer.NewMuxer(m.parser)
// Set a default handler for the child muxer (404 Not Found).
childMuxer.SetDefaultHandler(http.NotFoundHandler())
childCount := 0
for _, childName := range childRefs {
childRouter, exists := m.conf.Routers[childName]
if !exists {
return nil, fmt.Errorf("child router %q does not exist", childName)
}
// Skip child routers with errors.
if len(childRouter.Err) > 0 {
continue
}
logger := log.Ctx(ctx).With().Str(logs.RouterName, childName).Logger()
ctxChild := logger.WithContext(provider.AddInContext(ctx, childName))
// Set priority if not set.
if childRouter.Priority == 0 {
childRouter.Priority = httpmuxer.GetRulePriority(childRouter.Rule)
}
// Build the child router handler.
childHandler, err := m.buildRouterHandler(ctxChild, childName, childRouter)
if err != nil {
childRouter.AddError(err, true)
logger.Error().Err(err).Send()
continue
}
// Add the child router to the muxer.
if err = childMuxer.AddRoute(childRouter.Rule, childRouter.RuleSyntax, childRouter.Priority, childHandler); err != nil {
childRouter.AddError(err, true)
logger.Error().Err(err).Send()
continue
}
childCount++
}
// Prevent empty muxer.
if childCount == 0 {
return nil, fmt.Errorf("no child routers could be added to muxer (%d skipped)", len(childRefs))
}
return childMuxer, nil
}