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dispatcher.go
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dispatcher.go
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package gateway
import (
"context"
"encoding/json"
"fmt"
"github.com/pkg/errors"
"google.golang.org/protobuf/types/known/durationpb"
apiv2 "github.com/datawire/ambassador/v2/pkg/api/envoy/api/v2"
apiv2_core "github.com/datawire/ambassador/v2/pkg/api/envoy/api/v2/core"
apiv2_endpoint "github.com/datawire/ambassador/v2/pkg/api/envoy/api/v2/endpoint"
apiv2_route "github.com/datawire/ambassador/v2/pkg/api/envoy/api/v2/route"
ecp_cache_types "github.com/datawire/ambassador/v2/pkg/envoy-control-plane/cache/types"
ecp_v2_cache "github.com/datawire/ambassador/v2/pkg/envoy-control-plane/cache/v2"
ecp_v2_resource "github.com/datawire/ambassador/v2/pkg/envoy-control-plane/resource/v2"
ecp_wellknown "github.com/datawire/ambassador/v2/pkg/envoy-control-plane/wellknown"
"github.com/datawire/ambassador/v2/pkg/kates"
"github.com/datawire/dlib/dlog"
)
// The Dispatcher struct allows transforms to be registered for different kinds of kubernetes
// resources and invokes those transforms to produce compiled envoy configurations. It also knows
// how to assemble the compiled envoy configuration into a complete snapshot.
//
// Currently the dispatch process is relatively simple, each resource is processed as an independent
// unit. This is sufficient for the gateway API since the currently implemented resources are
// conveniently defined in such a way as to make them independent.
//
// Consistency is guaranteed assuming transform functions don't use out of band communication to
// include information from other resources. This guarantee is achieved because each transform is
// only passed a single resource and can therefore only use information from that one
// resource. Changes to any other resource cannot impact the result of that transform.
//
// Not all the edgestack resources are defined as conveniently, so the Dispatcher design is expected
// to be extended in two ways to handle resources with more complex interdependencies:
//
// 1. Grouping -- This feature would cover resources that need to be processed as a group,
// e.g. Mappings that get grouped together based on prefix. Instead of dispatching at the
// granularity of a single resource, the dispatcher will track groups of resources that need to
// be processed together via a logical "hash" function provided at registration. Whenever any
// item in a given bucket changes, the dispatcher will transform the entire bucket.
//
// 2. Dependencies -- This feature would cover resources that need to lookup the contents of other
// resources in order to properly implement their transform. This would be done by passing the
// transform function a Query API. Any resources queried by the transform would be
// automatically tracked as a dependency of that resource. The dependencies would then be used
// to perform invalidation whenever a resource is Upsert()ed.
//
type Dispatcher struct {
// Map from kind to transform function.
transforms map[string]func(kates.Object) (*CompiledConfig, error)
configs map[string]*CompiledConfig
version string
changeCount int
snapshot *ecp_v2_cache.Snapshot
endpointWatches map[string]bool
}
type ResourceRef struct {
Kind string
Namespace string
Name string
}
// resourceKey produces a fully qualified key for a kubernetes resource.
func resourceKey(resource kates.Object) string {
gvk := resource.GetObjectKind().GroupVersionKind()
return resourceKeyFromParts(gvk.Kind, resource.GetNamespace(), resource.GetName())
}
func resourceKeyFromParts(kind, namespace, name string) string {
return fmt.Sprintf("%s:%s:%s", kind, namespace, name)
}
// NewDispatcher creates a new and empty *Dispatcher struct.
func NewDispatcher() *Dispatcher {
return &Dispatcher{
transforms: map[string]func(kates.Object) (*CompiledConfig, error){},
configs: map[string]*CompiledConfig{},
}
}
// Register registers a transform function for the specified kubernetes resource. The transform
// argument must be a function that takes a single resource of the supplied "kind" and returns a
// single CompiledConfig object, i.e.: `func(Kind) *CompiledConfig`
func (d *Dispatcher) Register(kind string, transform func(kates.Object) (*CompiledConfig, error)) error {
_, ok := d.transforms[kind]
if ok {
return errors.Errorf("duplicate transform: %q", kind)
}
d.transforms[kind] = transform
return nil
}
// IsRegistered returns true if the given kind can be processed by this dispatcher.
func (d *Dispatcher) IsRegistered(kind string) bool {
_, ok := d.transforms[kind]
return ok
}
// Upsert processes the given kubernetes resource whether it is new or just updated.
func (d *Dispatcher) Upsert(resource kates.Object) error {
gvk := resource.GetObjectKind().GroupVersionKind()
xform, ok := d.transforms[gvk.Kind]
if !ok {
return errors.Errorf("no transform for kind: %q", gvk.Kind)
}
key := resourceKey(resource)
config, err := xform(resource)
if err != nil {
return errors.Wrapf(err, "internal error processing %s", key)
}
d.configs[key] = config
// Clear out the snapshot so we regenerate one.
d.snapshot = nil
return nil
}
// Delete processes the deletion of the given kubernetes resource.
func (d *Dispatcher) Delete(resource kates.Object) {
key := resourceKey(resource)
delete(d.configs, key)
// Clear out the snapshot so we regenerate one.
d.snapshot = nil
}
func (d *Dispatcher) DeleteKey(kind, namespace, name string) {
key := resourceKeyFromParts(kind, namespace, name)
delete(d.configs, key)
d.snapshot = nil
}
// UpsertYaml parses the supplied yaml and invokes Upsert on the result.
func (d *Dispatcher) UpsertYaml(manifests string) error {
objs, err := kates.ParseManifests(manifests)
if err != nil {
return err
}
for _, obj := range objs {
err := d.Upsert(obj)
if err != nil {
return err
}
}
return nil
}
// GetErrors returns all compiled items with errors.
func (d *Dispatcher) GetErrors() []*CompiledItem {
var result []*CompiledItem
for _, config := range d.configs {
if config.Error != "" {
result = append(result, &config.CompiledItem)
}
for _, l := range config.Listeners {
if l.Error != "" {
result = append(result, &l.CompiledItem)
}
}
for _, r := range config.Routes {
if r.Error != "" {
result = append(result, &r.CompiledItem)
}
for _, cr := range r.ClusterRefs {
if cr.Error != "" {
result = append(result, &cr.CompiledItem)
}
}
}
for _, c := range config.Clusters {
if c.Error != "" {
result = append(result, &c.CompiledItem)
}
}
for _, la := range config.LoadAssignments {
if la.Error != "" {
result = append(result, &la.CompiledItem)
}
}
}
return result
}
// GetSnapshot returns a version and a snapshot.
func (d *Dispatcher) GetSnapshot(ctx context.Context) (string, *ecp_v2_cache.Snapshot) {
if d.snapshot == nil {
d.buildSnapshot(ctx)
}
return d.version, d.snapshot
}
// GetListener returns a *apiv2.Listener with the specified name or nil if none exists.
func (d *Dispatcher) GetListener(ctx context.Context, name string) *apiv2.Listener {
_, snap := d.GetSnapshot(ctx)
for _, rsrc := range snap.Resources[ecp_cache_types.Listener].Items {
l := rsrc.(*apiv2.Listener)
if l.Name == name {
return l
}
}
return nil
}
// GetRouteConfiguration returns a *apiv2.RouteConfiguration with the specified name or nil if none
// exists.
func (d *Dispatcher) GetRouteConfiguration(ctx context.Context, name string) *apiv2.RouteConfiguration {
_, snap := d.GetSnapshot(ctx)
for _, rsrc := range snap.Resources[ecp_cache_types.Route].Items {
r := rsrc.(*apiv2.RouteConfiguration)
if r.Name == name {
return r
}
}
return nil
}
// IsWatched is a temporary hack for dealing with the way endpoint data currenttly flows from
// watcher -> ambex.n
func (d *Dispatcher) IsWatched(namespace, name string) bool {
key := fmt.Sprintf("%s:%s", namespace, name)
_, ok := d.endpointWatches[key]
return ok
}
func (d *Dispatcher) buildClusterMap() (map[string]string, map[string]bool) {
refs := map[string]string{}
watches := map[string]bool{}
for _, config := range d.configs {
for _, route := range config.Routes {
for _, ref := range route.ClusterRefs {
refs[ref.Name] = ref.EndpointPath
if route.Namespace != "" {
key := fmt.Sprintf("%s:%s", route.Namespace, ref.Name)
watches[key] = true
}
}
}
}
return refs, watches
}
func (d *Dispatcher) buildEndpointMap() map[string]*apiv2.ClusterLoadAssignment {
endpoints := map[string]*apiv2.ClusterLoadAssignment{}
for _, config := range d.configs {
for _, la := range config.LoadAssignments {
endpoints[la.LoadAssignment.ClusterName] = la.LoadAssignment
}
}
return endpoints
}
func (d *Dispatcher) buildRouteConfigurations() ([]ecp_cache_types.Resource, []ecp_cache_types.Resource) {
listeners := []ecp_cache_types.Resource{}
routes := []ecp_cache_types.Resource{}
for _, config := range d.configs {
for _, lst := range config.Listeners {
listeners = append(listeners, lst.Listener)
r := d.buildRouteConfiguration(lst)
if r != nil {
routes = append(routes, r)
}
}
}
return listeners, routes
}
func (d *Dispatcher) buildRouteConfiguration(lst *CompiledListener) *apiv2.RouteConfiguration {
rdsName, isRds := getRdsName(lst.Listener)
if !isRds {
return nil
}
var routes []*apiv2_route.Route
for _, config := range d.configs {
for _, route := range config.Routes {
if lst.Predicate(route) {
routes = append(routes, route.Routes...)
}
}
}
return &apiv2.RouteConfiguration{
Name: rdsName,
VirtualHosts: []*apiv2_route.VirtualHost{
{
Name: rdsName,
Domains: lst.Domains,
Routes: routes,
},
},
}
}
// getRdsName returns the RDS route configuration name configured for the listener and a flag
// indicating whether the listener uses Rds.
func getRdsName(l *apiv2.Listener) (string, bool) {
for _, fc := range l.FilterChains {
for _, f := range fc.Filters {
if f.Name != ecp_wellknown.HTTPConnectionManager {
continue
}
hcm := ecp_v2_resource.GetHTTPConnectionManager(f)
if hcm != nil {
rds := hcm.GetRds()
if rds != nil {
return rds.RouteConfigName, true
}
}
}
}
return "", false
}
func (d *Dispatcher) buildSnapshot(ctx context.Context) {
d.changeCount++
d.version = fmt.Sprintf("v%d", d.changeCount)
endpointMap := d.buildEndpointMap()
clusterMap, endpointWatches := d.buildClusterMap()
clusters := []ecp_cache_types.Resource{}
endpoints := []ecp_cache_types.Resource{}
for name, path := range clusterMap {
clusters = append(clusters, makeCluster(name, path))
key := path
if key == "" {
key = name
}
la, ok := endpointMap[key]
if ok {
endpoints = append(endpoints, la)
} else {
endpoints = append(endpoints, &apiv2.ClusterLoadAssignment{
ClusterName: key,
Endpoints: []*apiv2_endpoint.LocalityLbEndpoints{},
})
}
}
listeners, routes := d.buildRouteConfigurations()
snapshot := ecp_v2_cache.NewSnapshot(d.version, endpoints, clusters, routes, listeners, nil)
if err := snapshot.Consistent(); err != nil {
bs, _ := json.MarshalIndent(snapshot, "", " ")
dlog.Errorf(ctx, "Dispatcher Snapshot inconsistency: %v: %s", err, bs)
} else {
d.snapshot = &snapshot
d.endpointWatches = endpointWatches
}
}
func makeCluster(name, path string) *apiv2.Cluster {
return &apiv2.Cluster{
Name: name,
ConnectTimeout: &durationpb.Duration{Seconds: 10},
ClusterDiscoveryType: &apiv2.Cluster_Type{Type: apiv2.Cluster_EDS},
EdsClusterConfig: &apiv2.Cluster_EdsClusterConfig{
EdsConfig: &apiv2_core.ConfigSource{ConfigSourceSpecifier: &apiv2_core.ConfigSource_Ads{}},
ServiceName: path,
},
}
}