open-consul/agent/service_manager.go

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package agent
import (
"fmt"
"sync"
"github.com/imdario/mergo"
"github.com/mitchellh/copystructure"
"golang.org/x/net/context"
"github.com/hashicorp/consul/agent/cache"
cachetype "github.com/hashicorp/consul/agent/cache-types"
"github.com/hashicorp/consul/agent/structs"
)
// ServiceManager watches changes to central service config for all services
// registered with it. When a central config changes, the local service will
// be updated with the correct values from the central config.
type ServiceManager struct {
agent *Agent
// servicesLock guards the services map, but not the watches contained
// therein
servicesLock sync.Mutex
// services tracks all active watches for registered services
services map[structs.ServiceID]*serviceConfigWatch
// ctx is the shared context for all goroutines launched
ctx context.Context
// cancel can be used to stop all goroutines launched
cancel context.CancelFunc
// running keeps track of live goroutines (worker and watcher)
running sync.WaitGroup
}
func NewServiceManager(agent *Agent) *ServiceManager {
ctx, cancel := context.WithCancel(context.Background())
return &ServiceManager{
agent: agent,
services: make(map[structs.ServiceID]*serviceConfigWatch),
ctx: ctx,
cancel: cancel,
}
}
// Stop forces all background goroutines to terminate and blocks until they complete.
//
// NOTE: the caller must NOT hold the Agent.stateLock!
func (s *ServiceManager) Stop() {
s.cancel()
s.running.Wait()
}
// AddService will (re)create a serviceConfigWatch on the given service. For
// each call of this function the first registration will happen inline and
// will read the merged global defaults for the service through the agent cache
// (regardless of whether or not the service was already registered). This
// lets validation or authorization related errors bubble back up to the
// caller's RPC inline with their request. Upon success a goroutine will keep
// this updated in the background.
//
// If waitForCentralConfig=true is used, the initial registration blocks on
// fetching the merged global config through the cache. If false, no such RPC
// occurs and only the previousDefaults are used.
//
// persistServiceConfig controls if the INITIAL registration will result in
// persisting the service config to disk again. All background updates will
// always persist.
//
// service, chkTypes, persist, token, replaceExistingChecks, and source are
// basically pass-through arguments to Agent.addServiceInternal that follow the
// semantics there. The one key difference is that the service provided will be
// merged with the global defaults before registration.
//
// NOTE: the caller must hold the Agent.stateLock!
func (s *ServiceManager) AddService(req addServiceLockedRequest) error {
s.servicesLock.Lock()
defer s.servicesLock.Unlock()
sid := req.Service.CompoundServiceID()
// If a service watch already exists, shut it down and replace it.
oldWatch, updating := s.services[sid]
if updating {
oldWatch.Stop()
delete(s.services, sid)
}
// Get the existing global config and do the initial registration with the
// merged config.
watch := &serviceConfigWatch{registration: req, agent: s.agent}
if err := watch.register(s.ctx); err != nil {
return err
}
if err := watch.start(s.ctx, &s.running); err != nil {
return err
}
s.services[sid] = watch
if updating {
s.agent.logger.Debug("updated local registration for service", "service", req.Service.ID)
} else {
s.agent.logger.Debug("added local registration for service", "service", req.Service.ID)
}
return nil
}
// NOTE: the caller must hold the Agent.stateLock!
func (s *ServiceManager) RemoveService(serviceID structs.ServiceID) {
s.servicesLock.Lock()
defer s.servicesLock.Unlock()
if oldWatch, exists := s.services[serviceID]; exists {
oldWatch.Stop()
delete(s.services, serviceID)
}
}
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// serviceConfigWatch is a long running helper for composing the end config
// for a given service from both the local registration and the global
// service/proxy defaults.
type serviceConfigWatch struct {
registration addServiceLockedRequest
agent *Agent
// cacheKey stores the key of the current request, when registration changes
// we check to see if a new cache watch is needed.
cacheKey string
cancelFunc func()
running sync.WaitGroup
}
// NOTE: this is called while holding the Agent.stateLock
func (w *serviceConfigWatch) register(ctx context.Context) error {
serviceDefaults, err := w.registration.serviceDefaults(ctx)
if err != nil {
return fmt.Errorf("could not retrieve initial service_defaults config for service %q: %v",
w.registration.Service.ID, err)
}
// Merge the local registration with the central defaults and update this service
// in the local state.
merged, err := mergeServiceConfig(serviceDefaults, w.registration.Service)
if err != nil {
return err
}
// make a copy of the AddServiceRequest
req := w.registration
req.Service = merged
err = w.agent.addServiceInternal(addServiceInternalRequest{
addServiceLockedRequest: req,
persistService: w.registration.Service,
persistServiceDefaults: serviceDefaults,
})
if err != nil {
return fmt.Errorf("error updating service registration: %v", err)
}
return nil
}
func serviceDefaultsFromStruct(v *structs.ServiceConfigResponse) func(context.Context) (*structs.ServiceConfigResponse, error) {
return func(_ context.Context) (*structs.ServiceConfigResponse, error) {
return v, nil
}
}
func serviceDefaultsFromCache(bd BaseDeps, req AddServiceRequest) func(context.Context) (*structs.ServiceConfigResponse, error) {
// NOTE: this is called while holding the Agent.stateLock
return func(ctx context.Context) (*structs.ServiceConfigResponse, error) {
req := makeConfigRequest(bd, req)
raw, _, err := bd.Cache.Get(ctx, cachetype.ResolvedServiceConfigName, req)
if err != nil {
return nil, err
}
serviceConfig, ok := raw.(*structs.ServiceConfigResponse)
if !ok {
// This should never happen, but we want to protect against panics
return nil, fmt.Errorf("internal error: response type not correct")
}
return serviceConfig, nil
}
}
// Start starts the config watch and a goroutine to handle updates over the
// updateCh. This is safe to call more than once assuming you have called Stop
// after each Start.
//
// NOTE: this is called while holding the Agent.stateLock
func (w *serviceConfigWatch) start(ctx context.Context, wg *sync.WaitGroup) error {
ctx, w.cancelFunc = context.WithCancel(ctx)
// Configure and start a cache.Notify goroutine to run a continuous
// blocking query on the resolved service config for this service.
req := makeConfigRequest(w.agent.baseDeps, w.registration.AddServiceRequest)
w.cacheKey = req.CacheInfo().Key
updateCh := make(chan cache.UpdateEvent, 1)
// We use the cache key as the correlationID here. Notify in general will not
// respond on the updateCh after the context is cancelled however there could
// possible be a race where it has only just got an update and checked the
// context before we cancel and so might still deliver the old event. Using
// the cacheKey allows us to ignore updates from the old cache watch and makes
// even this rare edge case safe.
err := w.agent.cache.Notify(ctx, cachetype.ResolvedServiceConfigName, req, w.cacheKey, updateCh)
if err != nil {
w.cancelFunc()
return err
}
w.running.Add(1)
wg.Add(1)
go w.runWatch(ctx, wg, updateCh)
return nil
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}
func (w *serviceConfigWatch) Stop() {
w.cancelFunc()
w.running.Wait()
}
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// runWatch handles any update events from the cache.Notify until the
// config watch is shut down.
//
// NOTE: the caller must NOT hold the Agent.stateLock!
func (w *serviceConfigWatch) runWatch(ctx context.Context, wg *sync.WaitGroup, updateCh chan cache.UpdateEvent) {
defer wg.Done()
defer w.running.Done()
for {
select {
case <-ctx.Done():
return
case event := <-updateCh:
if err := w.handleUpdate(ctx, event); err != nil {
w.agent.logger.Error("error handling service update", "error", err)
}
}
}
}
// handleUpdate receives an update event the global config defaults, updates
// the local state and re-registers the service with the newly merged config.
//
// NOTE: the caller must NOT hold the Agent.stateLock!
func (w *serviceConfigWatch) handleUpdate(ctx context.Context, event cache.UpdateEvent) error {
// If we got an error, log a warning if this is the first update; otherwise return the error.
// We want the initial update to cause a service registration no matter what.
if event.Err != nil {
return fmt.Errorf("error watching service config: %v", event.Err)
}
serviceDefaults, ok := event.Result.(*structs.ServiceConfigResponse)
if !ok {
return fmt.Errorf("unknown update event type: %T", event)
}
// Sanity check this even came from the currently active watch to ignore
// rare races when switching cache keys
if event.CorrelationID != w.cacheKey {
// It's a no-op. The new watcher will deliver (or may have already
// delivered) the correct config so just ignore this old message.
return nil
}
// Merge the local registration with the central defaults and update this service
// in the local state.
merged, err := mergeServiceConfig(serviceDefaults, w.registration.Service)
if err != nil {
return err
}
// make a copy of the AddServiceRequest
req := w.registration
req.Service = merged
req.persistServiceConfig = true
args := addServiceInternalRequest{
addServiceLockedRequest: req,
persistService: w.registration.Service,
persistServiceDefaults: serviceDefaults,
}
if err := w.agent.stateLock.TryLock(ctx); err != nil {
return nil
}
defer w.agent.stateLock.Unlock()
// The context may have been cancelled after the lock was acquired.
if err := ctx.Err(); err != nil {
return nil
}
if err := w.agent.addServiceInternal(args); err != nil {
return fmt.Errorf("error updating service registration: %v", err)
}
return nil
}
func makeConfigRequest(bd BaseDeps, addReq AddServiceRequest) *structs.ServiceConfigRequest {
var (
ns = addReq.Service
name = ns.Service
id = ns.ID
node = addReq.nodeName
)
var upstreams []structs.ServiceID
// Note that only sidecar proxies should even make it here for now although
// later that will change to add the condition.
if ns.IsSidecarProxy() {
// This is a sidecar proxy, ignore the proxy service's config since we are
// managed by the target service config.
name = ns.Proxy.DestinationServiceName
// Also if we have any upstreams defined, add them to the request so we can
// learn about their configs.
for _, us := range ns.Proxy.Upstreams {
if us.DestinationType == "" || us.DestinationType == structs.UpstreamDestTypeService {
sid := us.DestinationID()
sid.EnterpriseMeta.Merge(&ns.EnterpriseMeta)
upstreams = append(upstreams, sid)
}
}
}
req := &structs.ServiceConfigRequest{
Name: name,
ID: id,
NodeName: node,
Datacenter: bd.RuntimeConfig.Datacenter,
QueryOptions: structs.QueryOptions{Token: addReq.token},
UpstreamIDs: upstreams,
EnterpriseMeta: ns.EnterpriseMeta,
}
if req.QueryOptions.Token == "" {
req.QueryOptions.Token = bd.Tokens.AgentToken()
}
return req
}
// mergeServiceConfig from service into defaults to produce the final effective
// config for the watched service.
func mergeServiceConfig(defaults *structs.ServiceConfigResponse, service *structs.NodeService) (*structs.NodeService, error) {
if defaults == nil {
return service, nil
}
// We don't want to change s.registration in place since it is our source of
// truth about what was actually registered before defaults applied. So copy
// it first.
nsRaw, err := copystructure.Copy(service)
if err != nil {
return nil, err
}
// Merge proxy defaults
ns := nsRaw.(*structs.NodeService)
if err := mergo.Merge(&ns.Proxy.Config, defaults.ProxyConfig); err != nil {
return nil, err
}
if err := mergo.Merge(&ns.Proxy.Expose, defaults.Expose); err != nil {
return nil, err
}
if ns.Proxy.MeshGateway.Mode == structs.MeshGatewayModeDefault {
ns.Proxy.MeshGateway.Mode = defaults.MeshGateway.Mode
}
if !ns.Proxy.TransparentProxy {
ns.Proxy.TransparentProxy = defaults.TransparentProxy
}
// seenUpstreams stores the upstreams seen from the local registration so that we can also add synthetic entries.
// for upstream configuration that was defined via service-defaults.UpstreamConfigs. In TransparentProxy mode
// ns.Proxy.Upstreams will likely be empty because users do not need to define upstreams explicitly.
// So to store upstream-specific flags from central config, we add entries to ns.Proxy.Upstream with thosee values.
remoteUpstreams := make(map[structs.ServiceID]structs.Upstream)
for _, us := range defaults.UpstreamIDConfigs {
parsed, err := structs.ParseUpstreamConfig(us.Config)
if err != nil {
return nil, fmt.Errorf("failed to parse upstream config map for %s: %v", us.Upstream.String(), err)
}
// Delete the mesh gateway key since this is the only place it is read from an opaque map.
// Later reads use Proxy.MeshGateway.
delete(us.Config, "mesh_gateway")
remoteUpstreams[us.Upstream] = structs.Upstream{
DestinationNamespace: us.Upstream.NamespaceOrDefault(),
DestinationName: us.Upstream.ID,
Config: us.Config,
MeshGateway: parsed.MeshGateway,
CentrallyConfigured: true,
}
}
localUpstreams := make(map[structs.ServiceID]struct{})
// Merge upstream defaults into the local registration
for i := range ns.Proxy.Upstreams {
// Get a pointer not a value copy of the upstream struct
us := &ns.Proxy.Upstreams[i]
if us.DestinationType != "" && us.DestinationType != structs.UpstreamDestTypeService {
continue
}
localUpstreams[us.DestinationID()] = struct{}{}
usCfg, ok := remoteUpstreams[us.DestinationID()]
if !ok {
// No config defaults to merge
continue
}
// The local upstream config mode has the highest precedence, so only overwrite when it's set to the default
if us.MeshGateway.Mode == structs.MeshGatewayModeDefault {
us.MeshGateway.Mode = usCfg.MeshGateway.Mode
}
// Merge in everything else that is read from the map
if err := mergo.Merge(&us.Config, usCfg.Config); err != nil {
return nil, err
}
}
// Ensure upstreams present in central config are represented in the local configuration.
// This does not apply outside of TransparentProxy mode because in that situation every upstream needs to be defined
// explicitly and locally with a local bind port.
if ns.Proxy.TransparentProxy {
for id, remote := range remoteUpstreams {
if _, ok := localUpstreams[id]; ok {
// Remote upstream is already present locally
continue
}
ns.Proxy.Upstreams = append(ns.Proxy.Upstreams, remote)
}
}
return ns, err
}