open-consul/agent/consul/state/federation_state.go

231 lines
6.3 KiB
Go
Raw Normal View History

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 state
import (
"fmt"
"github.com/hashicorp/consul/agent/structs"
memdb "github.com/hashicorp/go-memdb"
)
const federationStateTableName = "federation-states"
func federationStateTableSchema() *memdb.TableSchema {
return &memdb.TableSchema{
Name: federationStateTableName,
Indexes: map[string]*memdb.IndexSchema{
"id": &memdb.IndexSchema{
Name: "id",
AllowMissing: false,
Unique: true,
Indexer: &memdb.StringFieldIndex{
Field: "Datacenter",
Lowercase: true,
},
},
},
}
}
func init() {
registerSchema(federationStateTableSchema)
}
// FederationStates is used to pull all the federation states for the snapshot.
func (s *Snapshot) FederationStates() ([]*structs.FederationState, error) {
configs, err := s.tx.Get(federationStateTableName, "id")
if err != nil {
return nil, err
}
var ret []*structs.FederationState
for wrapped := configs.Next(); wrapped != nil; wrapped = configs.Next() {
ret = append(ret, wrapped.(*structs.FederationState))
}
return ret, nil
}
// FederationState is used when restoring from a snapshot.
func (s *Restore) FederationState(g *structs.FederationState) error {
// Insert
if err := s.tx.Insert(federationStateTableName, g); err != nil {
return fmt.Errorf("failed restoring federation state object: %s", err)
}
if err := indexUpdateMaxTxn(s.tx, g.ModifyIndex, federationStateTableName); err != nil {
return fmt.Errorf("failed updating index: %s", err)
}
return nil
}
func (s *Store) FederationStateBatchSet(idx uint64, configs structs.FederationStates) error {
tx := s.db.Txn(true)
defer tx.Abort()
for _, config := range configs {
if err := s.federationStateSetTxn(tx, idx, config); err != nil {
return err
}
}
tx.Commit()
return nil
}
// FederationStateSet is called to do an upsert of a given federation state.
func (s *Store) FederationStateSet(idx uint64, config *structs.FederationState) error {
tx := s.db.Txn(true)
defer tx.Abort()
if err := s.federationStateSetTxn(tx, idx, config); err != nil {
return err
}
tx.Commit()
return nil
}
// federationStateSetTxn upserts a federation state inside of a transaction.
func (s *Store) federationStateSetTxn(tx *memdb.Txn, idx uint64, config *structs.FederationState) error {
if config.Datacenter == "" {
return fmt.Errorf("missing datacenter on federation state")
}
// Check for existing.
var existing *structs.FederationState
existingRaw, err := tx.First(federationStateTableName, "id", config.Datacenter)
if err != nil {
return fmt.Errorf("failed federation state lookup: %s", err)
}
if existingRaw != nil {
existing = existingRaw.(*structs.FederationState)
}
// Set the indexes
if existing != nil {
config.CreateIndex = existing.CreateIndex
config.ModifyIndex = idx
} else {
config.CreateIndex = idx
config.ModifyIndex = idx
}
if config.PrimaryModifyIndex == 0 {
// Since replication ordinarily would set this value for us, we can
// assume this is a write to the primary datacenter's federation state
// so we can just duplicate the new modify index.
config.PrimaryModifyIndex = idx
}
// Insert the federation state and update the index
if err := tx.Insert(federationStateTableName, config); err != nil {
return fmt.Errorf("failed inserting federation state: %s", err)
}
if err := tx.Insert("index", &IndexEntry{federationStateTableName, idx}); err != nil {
return fmt.Errorf("failed updating index: %v", err)
}
return nil
}
// FederationStateGet is called to get a federation state.
func (s *Store) FederationStateGet(ws memdb.WatchSet, datacenter string) (uint64, *structs.FederationState, error) {
tx := s.db.Txn(false)
defer tx.Abort()
return s.federationStateGetTxn(tx, ws, datacenter)
}
func (s *Store) federationStateGetTxn(tx *memdb.Txn, ws memdb.WatchSet, datacenter string) (uint64, *structs.FederationState, error) {
// Get the index
idx := maxIndexTxn(tx, federationStateTableName)
// Get the existing contents.
watchCh, existing, err := tx.FirstWatch(federationStateTableName, "id", datacenter)
if err != nil {
return 0, nil, fmt.Errorf("failed federation state lookup: %s", err)
}
ws.Add(watchCh)
if existing == nil {
return idx, nil, nil
}
config, ok := existing.(*structs.FederationState)
if !ok {
return 0, nil, fmt.Errorf("federation state %q is an invalid type: %T", datacenter, config)
}
return idx, config, nil
}
// FederationStateList is called to get all federation state objects.
func (s *Store) FederationStateList(ws memdb.WatchSet) (uint64, []*structs.FederationState, error) {
tx := s.db.Txn(false)
defer tx.Abort()
return s.federationStateListTxn(tx, ws)
}
func (s *Store) federationStateListTxn(tx *memdb.Txn, ws memdb.WatchSet) (uint64, []*structs.FederationState, error) {
// Get the index
idx := maxIndexTxn(tx, federationStateTableName)
iter, err := tx.Get(federationStateTableName, "id")
if err != nil {
return 0, nil, fmt.Errorf("failed federation state lookup: %s", err)
}
ws.Add(iter.WatchCh())
var results []*structs.FederationState
for v := iter.Next(); v != nil; v = iter.Next() {
results = append(results, v.(*structs.FederationState))
}
return idx, results, nil
}
func (s *Store) FederationStateDelete(idx uint64, datacenter string) error {
tx := s.db.Txn(true)
defer tx.Abort()
if err := s.federationStateDeleteTxn(tx, idx, datacenter); err != nil {
return err
}
tx.Commit()
return nil
}
func (s *Store) FederationStateBatchDelete(idx uint64, datacenters []string) error {
tx := s.db.Txn(true)
defer tx.Abort()
for _, datacenter := range datacenters {
if err := s.federationStateDeleteTxn(tx, idx, datacenter); err != nil {
return err
}
}
tx.Commit()
return nil
}
func (s *Store) federationStateDeleteTxn(tx *memdb.Txn, idx uint64, datacenter string) error {
// Try to retrieve the existing federation state.
existing, err := tx.First(federationStateTableName, "id", datacenter)
if err != nil {
return fmt.Errorf("failed federation state lookup: %s", err)
}
if existing == nil {
return nil
}
// Delete the federation state from the DB and update the index.
if err := tx.Delete(federationStateTableName, existing); err != nil {
return fmt.Errorf("failed removing federation state: %s", err)
}
if err := tx.Insert("index", &IndexEntry{federationStateTableName, idx}); err != nil {
return fmt.Errorf("failed updating index: %s", err)
}
return nil
}