Avoid failover delays in twemproxy reconfig when using master targets

controllers/sentinel_controller.go

@@ -175,7 +175,8 @@ func (r *SentinelReconciler) reconcileStatus(ctx context.Context, instance *saas
 	// and rely on reconciles triggered by sentinel events to correct the situation.
 	masterError := &sharded.DiscoveryError_Master_SingleServerFailure{}
 	slaveError := &sharded.DiscoveryError_Slave_SingleServerFailure{}
-	if errors.As(merr, masterError) || errors.As(merr, slaveError) {
+	failoverInProgressError := &sharded.DiscoveryError_Slave_FailoverInProgress{}
+	if errors.As(merr, masterError) || errors.As(merr, slaveError) || errors.As(merr, failoverInProgressError) {
 		log.Error(merr, "DiscoveryError")
 	}
 

examples/backend/redis-v6/redis.yaml

@@ -4,15 +4,15 @@ metadata:
   name: shard01
 spec:
    image:
-     tag: 6.2.7-alpine
+     tag: 6.2.13-alpine
 ---
 apiVersion: saas.3scale.net/v1alpha1
 kind: RedisShard
 metadata:
   name: shard02
 spec:
    image:
-     tag: 6.2.7-alpine
+     tag: 6.2.13-alpine
 
 ---
 apiVersion: saas.3scale.net/v1alpha1
@@ -22,4 +22,4 @@ metadata:
 spec:
   slaveCount: 0
   image:
-    tag: 6.2.7-alpine
+    tag: 6.2.13-alpine

examples/backend/redis-v6/sentinel.yaml

@@ -5,7 +5,7 @@ metadata:
 spec:
   replicas: 3
   image:
-    tag: 6.2.7-debian-11-r17
+    tag: 6.2.13-debian-11-r76
   config:
     monitoredShards:
       # DNS should not be used in production. DNS is

go.mod

@@ -3,7 +3,7 @@ module github.com/3scale/saas-operator
 go 1.20
 
 require (
-	github.com/3scale-ops/basereconciler v0.3.4
+	github.com/3scale-ops/basereconciler v0.3.5
 	github.com/3scale-ops/marin3r v0.12.2
 	github.com/MakeNowJust/heredoc v1.0.0
 	github.com/aws/aws-sdk-go-v2 v1.21.0

go.sum

@@ -35,8 +35,8 @@ contrib.go.opencensus.io/exporter/ocagent v0.7.1-0.20200907061046-05415f1de66d/g
 contrib.go.opencensus.io/exporter/prometheus v0.4.0 h1:0QfIkj9z/iVZgK31D9H9ohjjIDApI2GOPScCKwxedbs=
 contrib.go.opencensus.io/exporter/prometheus v0.4.0/go.mod h1:o7cosnyfuPVK0tB8q0QmaQNhGnptITnPQB+z1+qeFB0=
 dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7gZCb22OMCxBHrMx7a5I7Hp++hsVxbQ4BYO7hU=
-github.com/3scale-ops/basereconciler v0.3.4 h1:KRA535+TNR0HCdGpxp/MwI9H2hPkTsIf0F+bo9ZqOFI=
-github.com/3scale-ops/basereconciler v0.3.4/go.mod h1:tPJ50gfzbDC52reWkDDaEHO1leuRx9JzqggwIRA+cL0=
+github.com/3scale-ops/basereconciler v0.3.5 h1:If2KDs6aOQ467Ja88bGFe2zkZy87AjXvXEWJDGwHbZs=
+github.com/3scale-ops/basereconciler v0.3.5/go.mod h1:xKM3TsE4qr4fiYCpKeodlcoJUruOpYsJ8M8Iz8FlEpg=
 github.com/3scale-ops/marin3r v0.12.2 h1:sU4N7RZ5AQzfejrfP0KgpagmL/XD8a5NdSIv1qvaAnU=
 github.com/3scale-ops/marin3r v0.12.2/go.mod h1:BOU7EFv58PgPMgKgJFDd4ingfBhH6KC2AGJoD7i9SaU=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=

pkg/generators/twemproxyconfig/generator_test.go

@@ -92,13 +92,27 @@ func TestNewGenerator(t *testing.T) {
 							},
 							InjectError: func() error { return nil },
 						},
+						redis_client.FakeResponse{
+							// cmd: SentinelGetMasterAddrByName (shard0)
+							InjectResponse: func() interface{} {
+								return []string{"127.0.0.1", "1000"}
+							},
+							InjectError: func() error { return nil },
+						},
 						redis_client.FakeResponse{
 							// cmd: SentinelMaster (shard1)
 							InjectResponse: func() interface{} {
 								return &redis_client.SentinelMasterCmdResult{Name: "shard1", IP: "127.0.0.1", Port: 5000, Flags: "master"}
 							},
 							InjectError: func() error { return nil },
 						},
+						redis_client.FakeResponse{
+							// cmd: SentinelGetMasterAddrByName (shard1)
+							InjectResponse: func() interface{} {
+								return []string{"127.0.0.1", "5000"}
+							},
+							InjectError: func() error { return nil },
+						},
 					),
 				),
 				log: logr.Discard(),
@@ -258,6 +272,13 @@ func TestNewGenerator(t *testing.T) {
 							},
 							InjectError: func() error { return nil },
 						},
+						redis_client.FakeResponse{
+							// cmd: SentinelGetMasterAddrByName (shard0)
+							InjectResponse: func() interface{} {
+								return []string{"127.0.0.1", "1000"}
+							},
+							InjectError: func() error { return nil },
+						},
 						redis_client.FakeResponse{
 							// cmd: SentinelSlaves (shard0)
 							InjectResponse: func() interface{} {
@@ -285,6 +306,13 @@ func TestNewGenerator(t *testing.T) {
 							},
 							InjectError: func() error { return nil },
 						},
+						redis_client.FakeResponse{
+							// cmd: SentinelGetMasterAddrByName (shard1)
+							InjectResponse: func() interface{} {
+								return []string{"127.0.0.1", "5000"}
+							},
+							InjectError: func() error { return nil },
+						},
 						redis_client.FakeResponse{
 							// cmd: SentinelSlaves (shard1)
 							InjectResponse: func() interface{} {
@@ -428,6 +456,13 @@ func TestNewGenerator(t *testing.T) {
 							},
 							InjectError: func() error { return nil },
 						},
+						redis_client.FakeResponse{
+							// cmd: SentinelGetMasterAddrByName (shard0)
+							InjectResponse: func() interface{} {
+								return []string{"127.0.0.1", "1000"}
+							},
+							InjectError: func() error { return nil },
+						},
 						redis_client.FakeResponse{
 							// cmd: SentinelSlaves (shard0)
 							InjectResponse: func() interface{} {
@@ -455,6 +490,13 @@ func TestNewGenerator(t *testing.T) {
 							},
 							InjectError: func() error { return nil },
 						},
+						redis_client.FakeResponse{
+							// cmd: SentinelGetMasterAddrByName (shard1)
+							InjectResponse: func() interface{} {
+								return []string{"127.0.0.1", "5000"}
+							},
+							InjectError: func() error { return nil },
+						},
 						redis_client.FakeResponse{
 							// cmd: SentinelSlaves (shard1)
 							InjectResponse: func() interface{} {
@@ -593,13 +635,27 @@ func TestNewGenerator(t *testing.T) {
 							},
 							InjectError: func() error { return nil },
 						},
+						redis_client.FakeResponse{
+							// cmd: SentinelGetMasterAddrByName (shard0)
+							InjectResponse: func() interface{} {
+								return []string{"127.0.0.1", "1000"}
+							},
+							InjectError: func() error { return nil },
+						},
 						redis_client.FakeResponse{
 							// cmd: SentinelMaster (shard1)
 							InjectResponse: func() interface{} {
 								return &redis_client.SentinelMasterCmdResult{Name: "shard1", IP: "127.0.0.1", Port: 5000, Flags: "master"}
 							},
 							InjectError: func() error { return nil },
 						},
+						redis_client.FakeResponse{
+							// cmd: SentinelGetMasterAddrByName (shard1)
+							InjectResponse: func() interface{} {
+								return []string{"127.0.0.1", "5000"}
+							},
+							InjectError: func() error { return nil },
+						},
 						redis_client.FakeResponse{
 							// cmd: SentinelSlaves (shard1)
 							InjectResponse: func() interface{} {

pkg/redis/client/fake_client.go

@@ -58,6 +58,11 @@ func (fc *FakeClient) SentinelMaster(ctx context.Context, shard string) (*Sentin
 	return rsp.InjectResponse().(*SentinelMasterCmdResult), rsp.InjectError()
 }
 
+func (fc *FakeClient) SentinelGetMasterAddrByName(ctx context.Context, shard string) ([]string, error) {
+	rsp := fc.pop()
+	return rsp.InjectResponse().([]string), rsp.InjectError()
+}
+
 func (fc *FakeClient) SentinelMasters(ctx context.Context) ([]interface{}, error) {
 	rsp := fc.pop()
 	return rsp.InjectResponse().([]interface{}), rsp.InjectError()

pkg/redis/client/goredis_client.go

@@ -73,6 +73,12 @@ func (c *GoRedisClient) SentinelMaster(ctx context.Context, shard string) (*Sent
 	return result, err
 }
 
+func (c *GoRedisClient) SentinelGetMasterAddrByName(ctx context.Context, shard string) ([]string, error) {
+
+	values, err := c.sentinel.GetMasterAddrByName(ctx, shard).Result()
+	return values, err
+}
+
 func (c *GoRedisClient) SentinelMasters(ctx context.Context) ([]interface{}, error) {
 
 	values, err := c.sentinel.Masters(ctx).Result()

pkg/redis/client/interface.go

@@ -13,6 +13,7 @@ import (
 type TestableInterface interface {
 	SentinelMaster(context.Context, string) (*SentinelMasterCmdResult, error)
 	SentinelMasters(context.Context) ([]interface{}, error)
+	SentinelGetMasterAddrByName(ctx context.Context, shard string) ([]string, error)
 	SentinelSlaves(context.Context, string) ([]interface{}, error)
 	SentinelMonitor(context.Context, string, string, string, int) error
 	SentinelSet(context.Context, string, string, string) error

pkg/redis/server/server.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"context"
 	"net"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -109,6 +110,19 @@ func (srv *Server) SentinelMaster(ctx context.Context, shard string) (*client.Se
 	return result, nil
 }
 
+func (srv *Server) SentinelGetMasterAddrByName(ctx context.Context, shard string) (string, int, error) {
+
+	values, err := srv.client.SentinelGetMasterAddrByName(ctx, shard)
+	if err != nil {
+		return "", 0, err
+	}
+	port, err := strconv.Atoi(values[1])
+	if err != nil {
+		return "", 0, err
+	}
+	return values[0], port, nil
+}
+
 func (srv *Server) SentinelMasters(ctx context.Context) ([]client.SentinelMasterCmdResult, error) {
 
 	values, err := srv.client.SentinelMasters(ctx)

pkg/redis/sharded/discover.go

@@ -105,5 +105,6 @@ func (srv *RedisServer) Discover(ctx context.Context, opts ...DiscoveryOption) e
 // Discovery errors
 type DiscoveryError_Sentinel_Failure struct{ error }
 type DiscoveryError_Master_SingleServerFailure struct{ error }
+type DiscoveryError_Slave_FailoverInProgress struct{ error }
 type DiscoveryError_Slave_SingleServerFailure struct{ error }
 type DiscoveryError_UnknownRole_SingleServerFailure struct{ error }

pkg/redis/sharded/redis_shard.go

@@ -3,7 +3,9 @@ package sharded
 import (
 	"context"
 	"fmt"
+	"net"
 	"sort"
+	"strconv"
 	"strings"
 
 	"github.com/3scale/saas-operator/pkg/redis/client"
@@ -79,6 +81,22 @@ func (shard *Shard) Discover(ctx context.Context, sentinel *SentinelServer, opti
 			return append(merr, DiscoveryError_Sentinel_Failure{err})
 		}
 
+		// If a failover is currently in progress, only the GetMasterAddrByName command returns the
+		// updated address of the master. The other commands ('sentinel masters' and 'sentinel master <shard>)
+		// wait until all the replicas are also reconfigured to start announcing the new IP, which can cause delays
+		// to reconfigure the clients.
+		failoverInProgress := false
+		masterIP, masterPort, err := sentinel.SentinelGetMasterAddrByName(ctx, shard.Name)
+		if err != nil {
+			return append(merr, DiscoveryError_Sentinel_Failure{err})
+		}
+		if masterIP != sentinelMasterResult.IP || masterPort != sentinelMasterResult.Port {
+			failoverInProgress = true
+			logger.Info("failover in progress", "oldMaster", net.JoinHostPort(sentinelMasterResult.IP, strconv.Itoa(sentinelMasterResult.Port)), "newMaster", net.JoinHostPort(masterIP, strconv.Itoa(masterPort)))
+			sentinelMasterResult.IP = masterIP
+			sentinelMasterResult.Port = masterPort
+		}
+
 		// Get the corresponding server or add a new one if not found
 		srv, err := shard.GetServerByID(fmt.Sprintf("%s:%d", sentinelMasterResult.IP, sentinelMasterResult.Port))
 		if err != nil {
@@ -108,6 +126,11 @@ func (shard *Shard) Discover(ctx context.Context, sentinel *SentinelServer, opti
 			return merr.ErrorOrNil()
 		}
 
+		// don't discover slaves if a failover is in progress
+		if failoverInProgress {
+			return append(merr, DiscoveryError_Slave_FailoverInProgress{fmt.Errorf("refusing to discover slaves while a failover is in progress")})
+		}
+
 		// discover slaves
 		sentinelSlavesResult, err := sentinel.SentinelSlaves(ctx, shard.Name)
 		if err != nil {