/
leader_federation_state_ae.go
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/
leader_federation_state_ae.go
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package consul
import (
"context"
"fmt"
"time"
memdb "github.com/hashicorp/go-memdb"
"github.com/hashicorp/consul/agent/consul/state"
"github.com/hashicorp/consul/agent/structs"
)
const (
// federationStatePruneInterval is how often we check for stale federation
// states to remove should a datacenter be removed from the WAN.
federationStatePruneInterval = time.Hour
)
func (s *Server) startFederationStateAntiEntropy(ctx context.Context) {
// Check to see if we can skip waiting for serf feature detection below.
if !s.DatacenterSupportsFederationStates() {
_, fedStates, err := s.fsm.State().FederationStateList(nil)
if err != nil {
s.logger.Warn("Failed to check for existing federation states and activate the feature flag quicker; skipping this optimization", "error", err)
} else if len(fedStates) > 0 {
s.setDatacenterSupportsFederationStates()
}
}
if s.config.DisableFederationStateAntiEntropy {
return
}
s.leaderRoutineManager.Start(ctx, federationStateAntiEntropyRoutineName, s.federationStateAntiEntropySync)
// If this is the primary, then also prune any stale datacenters from the
// list of federation states.
if s.config.PrimaryDatacenter == s.config.Datacenter {
s.leaderRoutineManager.Start(ctx, federationStatePruningRoutineName, s.federationStatePruning)
}
}
func (s *Server) stopFederationStateAntiEntropy() {
if s.config.DisableFederationStateAntiEntropy {
return
}
s.leaderRoutineManager.Stop(federationStateAntiEntropyRoutineName)
if s.config.PrimaryDatacenter == s.config.Datacenter {
s.leaderRoutineManager.Stop(federationStatePruningRoutineName)
}
}
func (s *Server) federationStateAntiEntropySync(ctx context.Context) error {
var lastFetchIndex uint64
retryLoopBackoff(ctx, func() error {
if !s.DatacenterSupportsFederationStates() {
return nil
}
idx, err := s.federationStateAntiEntropyMaybeSync(ctx, lastFetchIndex)
if err != nil {
return err
}
lastFetchIndex = idx
return nil
}, func(err error) {
s.logger.Error("error performing anti-entropy sync of federation state", "error", err)
})
return nil
}
func (s *Server) federationStateAntiEntropyMaybeSync(ctx context.Context, lastFetchIndex uint64) (uint64, error) {
queryOpts := &structs.QueryOptions{
MinQueryIndex: lastFetchIndex,
RequireConsistent: true,
// This is just for a local blocking query so no token is needed.
}
idx, prev, curr, err := s.fetchFederationStateAntiEntropyDetails(queryOpts)
if err != nil {
return 0, err
}
// We should check to see if our context was cancelled while we were blocked.
select {
case <-ctx.Done():
return 0, ctx.Err()
default:
}
if prev != nil && prev.IsSame(curr) {
s.logger.Trace("federation state anti-entropy sync skipped; already up to date")
return idx, nil
}
if err := s.updateOurFederationState(curr); err != nil {
return 0, fmt.Errorf("error performing federation state anti-entropy sync: %v", err)
}
s.logger.Info("federation state anti-entropy synced")
return idx, nil
}
func (s *Server) updateOurFederationState(curr *structs.FederationState) error {
if curr.Datacenter != s.config.Datacenter { // sanity check
return fmt.Errorf("cannot use this mechanism to update federation states for other datacenters")
}
curr.UpdatedAt = time.Now().UTC()
args := structs.FederationStateRequest{
Op: structs.FederationStateUpsert,
State: curr,
}
if s.config.Datacenter == s.config.PrimaryDatacenter {
// We are the primary, so we can't do an RPC as we don't have a replication token.
_, err := s.raftApply(structs.FederationStateRequestType, args)
if err != nil {
return err
}
} else {
args.WriteRequest = structs.WriteRequest{
Token: s.tokens.ReplicationToken(),
}
ignored := false
if err := s.forwardDC("FederationState.Apply", s.config.PrimaryDatacenter, &args, &ignored); err != nil {
return err
}
}
return nil
}
func (s *Server) fetchFederationStateAntiEntropyDetails(
queryOpts *structs.QueryOptions,
) (uint64, *structs.FederationState, *structs.FederationState, error) {
var (
prevFedState, currFedState *structs.FederationState
queryMeta structs.QueryMeta
)
err := s.blockingQuery(
queryOpts,
&queryMeta,
func(ws memdb.WatchSet, state *state.Store) error {
// Get the existing stored version of this FedState that has replicated down.
// We could phone home to get this but that would incur extra WAN traffic
// when we already have enough information locally to figure it out
// (assuming that our replicator is still functioning).
idx1, prev, err := state.FederationStateGet(ws, s.config.Datacenter)
if err != nil {
return err
}
// Fetch our current list of all mesh gateways.
entMeta := structs.WildcardEnterpriseMeta()
idx2, raw, err := state.ServiceDump(ws, structs.ServiceKindMeshGateway, true, entMeta)
if err != nil {
return err
}
curr := &structs.FederationState{
Datacenter: s.config.Datacenter,
MeshGateways: raw,
}
// Compute the maximum index seen.
if idx2 > idx1 {
queryMeta.Index = idx2
} else {
queryMeta.Index = idx1
}
prevFedState = prev
currFedState = curr
return nil
})
if err != nil {
return 0, nil, nil, err
}
return queryMeta.Index, prevFedState, currFedState, nil
}
func (s *Server) federationStatePruning(ctx context.Context) error {
ticker := time.NewTicker(federationStatePruneInterval)
defer ticker.Stop()
for {
select {
case <-ctx.Done():
return nil
case <-ticker.C:
if err := s.pruneStaleFederationStates(); err != nil {
s.logger.Error("error pruning stale federation states", "error", err)
}
}
}
}
func (s *Server) pruneStaleFederationStates() error {
state := s.fsm.State()
_, fedStates, err := state.FederationStateList(nil)
if err != nil {
return err
}
for _, fedState := range fedStates {
dc := fedState.Datacenter
if s.router.HasDatacenter(dc) {
continue
}
s.logger.Info("pruning stale federation state", "datacenter", dc)
req := structs.FederationStateRequest{
Op: structs.FederationStateDelete,
State: &structs.FederationState{
Datacenter: dc,
},
}
_, err := s.raftApply(structs.FederationStateRequestType, &req)
if err != nil {
return fmt.Errorf("Failed to delete federation state %s: %v", dc, err)
}
}
return nil
}