open-consul/agent/consul/config_replication.go

200 lines
6.9 KiB
Go

package consul
import (
"context"
"fmt"
"sort"
"time"
"github.com/armon/go-metrics"
"github.com/hashicorp/consul/agent/structs"
)
func cmpConfigLess(first structs.ConfigEntry, second structs.ConfigEntry) bool {
return first.GetKind() < second.GetKind() || (first.GetKind() == second.GetKind() && first.GetName() < second.GetName())
}
func configSort(configs []structs.ConfigEntry) {
sort.Slice(configs, func(i, j int) bool {
return cmpConfigLess(configs[i], configs[j])
})
}
func diffConfigEntries(local []structs.ConfigEntry, remote []structs.ConfigEntry, lastRemoteIndex uint64) ([]structs.ConfigEntry, []structs.ConfigEntry) {
configSort(local)
configSort(remote)
var deletions []structs.ConfigEntry
var updates []structs.ConfigEntry
var localIdx int
var remoteIdx int
for localIdx, remoteIdx = 0, 0; localIdx < len(local) && remoteIdx < len(remote); {
if local[localIdx].GetKind() == remote[remoteIdx].GetKind() && local[localIdx].GetName() == remote[remoteIdx].GetName() {
// config is in both the local and remote state - need to check raft indices
if remote[remoteIdx].GetRaftIndex().ModifyIndex > lastRemoteIndex {
updates = append(updates, remote[remoteIdx])
}
// increment both indices when equal
localIdx += 1
remoteIdx += 1
} else if cmpConfigLess(local[localIdx], remote[remoteIdx]) {
// config no longer in remoted state - needs deleting
deletions = append(deletions, local[localIdx])
// increment just the local index
localIdx += 1
} else {
// local state doesn't have this config - needs updating
updates = append(updates, remote[remoteIdx])
// increment just the remote index
remoteIdx += 1
}
}
for ; localIdx < len(local); localIdx += 1 {
deletions = append(deletions, local[localIdx])
}
for ; remoteIdx < len(remote); remoteIdx += 1 {
updates = append(updates, remote[remoteIdx])
}
return deletions, updates
}
func (s *Server) reconcileLocalConfig(ctx context.Context, configs []structs.ConfigEntry, op structs.ConfigEntryOp) (bool, error) {
ticker := time.NewTicker(time.Second / time.Duration(s.config.ConfigReplicationApplyLimit))
defer ticker.Stop()
for i, entry := range configs {
req := structs.ConfigEntryRequest{
Op: op,
Datacenter: s.config.Datacenter,
Entry: entry,
}
resp, err := s.raftApply(structs.ConfigEntryRequestType, &req)
if err != nil {
return false, fmt.Errorf("Failed to apply config %s: %v", op, err)
}
if respErr, ok := resp.(error); ok && err != nil {
return false, fmt.Errorf("Failed to apply config %s: %v", op, respErr)
}
if i < len(configs)-1 {
select {
case <-ctx.Done():
return true, nil
case <-ticker.C:
// do nothing - ready for the next batch
}
}
}
return false, nil
}
func (s *Server) fetchConfigEntries(lastRemoteIndex uint64) (*structs.IndexedGenericConfigEntries, error) {
defer metrics.MeasureSince([]string{"leader", "replication", "config-entries", "fetch"}, time.Now())
req := structs.DCSpecificRequest{
Datacenter: s.config.PrimaryDatacenter,
QueryOptions: structs.QueryOptions{
AllowStale: true,
MinQueryIndex: lastRemoteIndex,
Token: s.tokens.ReplicationToken(),
},
}
var response structs.IndexedGenericConfigEntries
if err := s.RPC("ConfigEntry.ListAll", &req, &response); err != nil {
return nil, err
}
return &response, nil
}
func (s *Server) replicateConfig(ctx context.Context, lastRemoteIndex uint64) (uint64, bool, error) {
remote, err := s.fetchConfigEntries(lastRemoteIndex)
if err != nil {
return 0, false, fmt.Errorf("failed to retrieve remote config entries: %v", err)
}
s.logger.Printf("[DEBUG] replication: finished fetching config entries: %d", len(remote.Entries))
// Need to check if we should be stopping. This will be common as the fetching process is a blocking
// RPC which could have been hanging around for a long time and during that time leadership could
// have been lost.
select {
case <-ctx.Done():
return 0, true, nil
default:
// do nothing
}
// Measure everything after the remote query, which can block for long
// periods of time. This metric is a good measure of how expensive the
// replication process is.
defer metrics.MeasureSince([]string{"leader", "replication", "config", "apply"}, time.Now())
_, local, err := s.fsm.State().ConfigEntries(nil)
if err != nil {
return 0, false, fmt.Errorf("failed to retrieve local config entries: %v", err)
}
// If the remote index ever goes backwards, it's a good indication that
// the remote side was rebuilt and we should do a full sync since we
// can't make any assumptions about what's going on.
//
// Resetting lastRemoteIndex to 0 will work because we never consider local
// raft indices. Instead we compare the raft modify index in the response object
// with the lastRemoteIndex (only when we already have a config entry of the same kind/name)
// to determine if an update is needed. Resetting lastRemoteIndex to 0 then has the affect
// of making us think all the local state is out of date and any matching entries should
// still be updated.
//
// The lastRemoteIndex is not used when the entry exists either only in the local state or
// only in the remote state. In those situations we need to either delete it or create it.
if remote.QueryMeta.Index < lastRemoteIndex {
s.logger.Printf("[WARN] replication: Config Entry replication remote index moved backwards (%d to %d), forcing a full Config Entry sync", lastRemoteIndex, remote.QueryMeta.Index)
lastRemoteIndex = 0
}
s.logger.Printf("[DEBUG] replication: Config Entry replication - local: %d, remote: %d", len(local), len(remote.Entries))
// Calculate the changes required to bring the state into sync and then
// apply them.
deletions, updates := diffConfigEntries(local, remote.Entries, lastRemoteIndex)
s.logger.Printf("[DEBUG] replication: Config Entry replication - deletions: %d, updates: %d", len(deletions), len(updates))
if len(deletions) > 0 {
s.logger.Printf("[DEBUG] replication: Config Entry replication - performing %d deletions", len(deletions))
exit, err := s.reconcileLocalConfig(ctx, deletions, structs.ConfigEntryDelete)
if exit {
return 0, true, nil
}
if err != nil {
return 0, false, fmt.Errorf("failed to delete local config entries: %v", err)
}
s.logger.Printf("[DEBUG] replication: Config Entry replication - finished deletions")
}
if len(updates) > 0 {
s.logger.Printf("[DEBUG] replication: Config Entry replication - performing %d updates", len(updates))
exit, err := s.reconcileLocalConfig(ctx, updates, structs.ConfigEntryUpsert)
if exit {
return 0, true, nil
}
if err != nil {
return 0, false, fmt.Errorf("failed to update local config entries: %v", err)
}
s.logger.Printf("[DEBUG] replication: Config Entry replication - finished updates")
}
// Return the index we got back from the remote side, since we've synced
// up with the remote state as of that index.
return remote.QueryMeta.Index, false, nil
}