open-consul/agent/consul/leader_federation_state_ae.go

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wan federation via mesh gateways (#6884) This is like a Möbius strip of code due to the fact that low-level components (serf/memberlist) are connected to high-level components (the catalog and mesh-gateways) in a twisty maze of references which make it hard to dive into. With that in mind here's a high level summary of what you'll find in the patch: There are several distinct chunks of code that are affected: * new flags and config options for the server * retry join WAN is slightly different * retry join code is shared to discover primary mesh gateways from secondary datacenters * because retry join logic runs in the *agent* and the results of that operation for primary mesh gateways are needed in the *server* there are some methods like `RefreshPrimaryGatewayFallbackAddresses` that must occur at multiple layers of abstraction just to pass the data down to the right layer. * new cache type `FederationStateListMeshGatewaysName` for use in `proxycfg/xds` layers * the function signature for RPC dialing picked up a new required field (the node name of the destination) * several new RPCs for manipulating a FederationState object: `FederationState:{Apply,Get,List,ListMeshGateways}` * 3 read-only internal APIs for debugging use to invoke those RPCs from curl * raft and fsm changes to persist these FederationStates * replication for FederationStates as they are canonically stored in the Primary and replicated to the Secondaries. * a special derivative of anti-entropy that runs in secondaries to snapshot their local mesh gateway `CheckServiceNodes` and sync them into their upstream FederationState in the primary (this works in conjunction with the replication to distribute addresses for all mesh gateways in all DCs to all other DCs) * a "gateway locator" convenience object to make use of this data to choose the addresses of gateways to use for any given RPC or gossip operation to a remote DC. This gets data from the "retry join" logic in the agent and also directly calls into the FSM. * RPC (`:8300`) on the server sniffs the first byte of a new connection to determine if it's actually doing native TLS. If so it checks the ALPN header for protocol determination (just like how the existing system uses the type-byte marker). * 2 new kinds of protocols are exclusively decoded via this native TLS mechanism: one for ferrying "packet" operations (udp-like) from the gossip layer and one for "stream" operations (tcp-like). The packet operations re-use sockets (using length-prefixing) to cut down on TLS re-negotiation overhead. * the server instances specially wrap the `memberlist.NetTransport` when running with gateway federation enabled (in a `wanfed.Transport`). The general gist is that if it tries to dial a node in the SAME datacenter (deduced by looking at the suffix of the node name) there is no change. If dialing a DIFFERENT datacenter it is wrapped up in a TLS+ALPN blob and sent through some mesh gateways to eventually end up in a server's :8300 port. * a new flag when launching a mesh gateway via `consul connect envoy` to indicate that the servers are to be exposed. This sets a special service meta when registering the gateway into the catalog. * `proxycfg/xds` notice this metadata blob to activate additional watches for the FederationState objects as well as the location of all of the consul servers in that datacenter. * `xds:` if the extra metadata is in place additional clusters are defined in a DC to bulk sink all traffic to another DC's gateways. For the current datacenter we listen on a wildcard name (`server.<dc>.consul`) that load balances all servers as well as one mini-cluster per node (`<node>.server.<dc>.consul`) * the `consul tls cert create` command got a new flag (`-node`) to help create an additional SAN in certs that can be used with this flavor of federation.
2020-03-09 20:59:02 +00:00
package consul
import (
"context"
"fmt"
"time"
"github.com/hashicorp/consul/agent/consul/state"
"github.com/hashicorp/consul/agent/structs"
memdb "github.com/hashicorp/go-memdb"
)
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() {
if s.config.DisableFederationStateAntiEntropy {
return
}
s.leaderRoutineManager.Start(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(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.Done(), func() error {
if !s.DatacenterSupportsFederationStates() {
return nil
}
wan federation via mesh gateways (#6884) This is like a Möbius strip of code due to the fact that low-level components (serf/memberlist) are connected to high-level components (the catalog and mesh-gateways) in a twisty maze of references which make it hard to dive into. With that in mind here's a high level summary of what you'll find in the patch: There are several distinct chunks of code that are affected: * new flags and config options for the server * retry join WAN is slightly different * retry join code is shared to discover primary mesh gateways from secondary datacenters * because retry join logic runs in the *agent* and the results of that operation for primary mesh gateways are needed in the *server* there are some methods like `RefreshPrimaryGatewayFallbackAddresses` that must occur at multiple layers of abstraction just to pass the data down to the right layer. * new cache type `FederationStateListMeshGatewaysName` for use in `proxycfg/xds` layers * the function signature for RPC dialing picked up a new required field (the node name of the destination) * several new RPCs for manipulating a FederationState object: `FederationState:{Apply,Get,List,ListMeshGateways}` * 3 read-only internal APIs for debugging use to invoke those RPCs from curl * raft and fsm changes to persist these FederationStates * replication for FederationStates as they are canonically stored in the Primary and replicated to the Secondaries. * a special derivative of anti-entropy that runs in secondaries to snapshot their local mesh gateway `CheckServiceNodes` and sync them into their upstream FederationState in the primary (this works in conjunction with the replication to distribute addresses for all mesh gateways in all DCs to all other DCs) * a "gateway locator" convenience object to make use of this data to choose the addresses of gateways to use for any given RPC or gossip operation to a remote DC. This gets data from the "retry join" logic in the agent and also directly calls into the FSM. * RPC (`:8300`) on the server sniffs the first byte of a new connection to determine if it's actually doing native TLS. If so it checks the ALPN header for protocol determination (just like how the existing system uses the type-byte marker). * 2 new kinds of protocols are exclusively decoded via this native TLS mechanism: one for ferrying "packet" operations (udp-like) from the gossip layer and one for "stream" operations (tcp-like). The packet operations re-use sockets (using length-prefixing) to cut down on TLS re-negotiation overhead. * the server instances specially wrap the `memberlist.NetTransport` when running with gateway federation enabled (in a `wanfed.Transport`). The general gist is that if it tries to dial a node in the SAME datacenter (deduced by looking at the suffix of the node name) there is no change. If dialing a DIFFERENT datacenter it is wrapped up in a TLS+ALPN blob and sent through some mesh gateways to eventually end up in a server's :8300 port. * a new flag when launching a mesh gateway via `consul connect envoy` to indicate that the servers are to be exposed. This sets a special service meta when registering the gateway into the catalog. * `proxycfg/xds` notice this metadata blob to activate additional watches for the FederationState objects as well as the location of all of the consul servers in that datacenter. * `xds:` if the extra metadata is in place additional clusters are defined in a DC to bulk sink all traffic to another DC's gateways. For the current datacenter we listen on a wildcard name (`server.<dc>.consul`) that load balances all servers as well as one mini-cluster per node (`<node>.server.<dc>.consul`) * the `consul tls cert create` command got a new flag (`-node`) to help create an additional SAN in certs that can be used with this flavor of federation.
2020-03-09 20:59:02 +00:00
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.
resp, err := s.raftApply(structs.FederationStateRequestType, args)
if err != nil {
return err
}
if respErr, ok := resp.(error); ok {
return respErr
}
} 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,
},
}
resp, err := s.raftApply(structs.FederationStateRequestType, &req)
if err != nil {
return fmt.Errorf("Failed to delete federation state %s: %v", dc, err)
}
if respErr, ok := resp.(error); ok && err != nil {
return fmt.Errorf("Failed to delete federation state %s: %v", dc, respErr)
}
}
return nil
}