feat(redis): support redis failover (sentinel) (#38)

* feat(redisfailover): support redis failover (sentinel)

This adds the go-redis/redis FailoverClient which is used for Redis Sentinel.

* fix(redisfailover): sentinel password

* refactor(redisfailover): combine with redis provider

* refactor(redis): expressly define structs

* refactor: use upstream addrs name

* fix: invalid struct key

* refactor: remove cluster for a later PR

* fix(redis): remove invalid options for failover

the routing options are only valid for cluster clients as per upstream docs

* refactor(redis): support both NewFailoverClient and NewFailoverClusterClient

The documentation upstream is slightly confusing. This has already been tested upstream by Authelia.

* docs(redis): add docs about the different clients and their purpose.

* docs(redis): add go-docs

* refactor: keyprefix -> keyPrefix

providers/redis/README.md

@@ -6,3 +6,15 @@ Better encoder:
 
 - Encode: `session.MSGPEncode`
 - Decode: `session.MSGPDecode`
+
+## Clients
+
+The redis provider supports the upstream standard client via New(), the sentinel client via NewFailover(), and
+the sentinel fail over client via NewFailoverCluster(). 
+
+The difference between the standard client and the sentinel clients is that the standard client will only connect to a 
+single redis server and the sentinel clients will connect to sentinel servers and figure out which redis server 
+to connect to automatically. This allows for a failure of a redis server if you configure sentinel and redis correctly. 
+
+The difference between the sentinel client via NewFailover() and the sentinel fail over client via NewFailoverCluster()
+is the fail over client will fail over to other sentinels if they are configured in the event of a failure.

providers/redis/errors.go

@@ -7,6 +7,8 @@ import (
 
 var errConfigAddrEmpty = errors.New("Config Addr must not be empty")
 
+var errConfigMasterNameEmpty = errors.New("Config MasterName must not be empty")
+
 func errRedisConnection(err error) error {
 	return fmt.Errorf("Redis connection error: %v", err)
 }

providers/redis/provider.go

@@ -43,16 +43,100 @@ func New(cfg Config) (*Provider, error) {
 	}
 
 	p := &Provider{
-		config: cfg,
-		db:     db,
+		keyPrefix: cfg.KeyPrefix,
+		db:        db,
+	}
+
+	return p, nil
+}
+
+// NewFailover returns a new redis provider using sentinel to determine the redis server to connect to.
+func NewFailover(cfg FailoverConfig) (*Provider, error) {
+	if cfg.MasterName == "" {
+		return nil, errConfigMasterNameEmpty
+	}
+
+	db := redis.NewFailoverClient(&redis.FailoverOptions{
+		MasterName:         cfg.MasterName,
+		SentinelAddrs:      cfg.SentinelAddrs,
+		SentinelPassword:   cfg.SentinelPassword,
+		SlaveOnly:          cfg.SlaveOnly,
+		Username:           cfg.Username,
+		Password:           cfg.Password,
+		DB:                 cfg.DB,
+		MaxRetries:         cfg.MaxRetries,
+		MinRetryBackoff:    cfg.MinRetryBackoff,
+		MaxRetryBackoff:    cfg.MaxRetryBackoff,
+		DialTimeout:        cfg.DialTimeout,
+		ReadTimeout:        cfg.ReadTimeout,
+		WriteTimeout:       cfg.WriteTimeout,
+		PoolSize:           cfg.PoolSize,
+		MinIdleConns:       cfg.MinIdleConns,
+		MaxConnAge:         cfg.MaxConnAge,
+		PoolTimeout:        cfg.PoolTimeout,
+		IdleTimeout:        cfg.IdleTimeout,
+		IdleCheckFrequency: cfg.IdleCheckFrequency,
+		TLSConfig:          cfg.TLSConfig,
+	})
+
+	if err := db.Ping(context.Background()).Err(); err != nil {
+		return nil, errRedisConnection(err)
+	}
+
+	p := &Provider{
+		keyPrefix: cfg.KeyPrefix,
+		db:        db,
+	}
+
+	return p, nil
+}
+
+// NewFailoverCluster returns a new redis provider using a group of sentinels to determine the redis server to connect to.
+func NewFailoverCluster(cfg FailoverConfig) (*Provider, error) {
+	if cfg.MasterName == "" {
+		return nil, errConfigMasterNameEmpty
+	}
+
+	db := redis.NewFailoverClusterClient(&redis.FailoverOptions{
+		MasterName:         cfg.MasterName,
+		SentinelAddrs:      cfg.SentinelAddrs,
+		SentinelPassword:   cfg.SentinelPassword,
+		RouteByLatency:     cfg.RouteByLatency,
+		RouteRandomly:      cfg.RouteRandomly,
+		SlaveOnly:          cfg.SlaveOnly,
+		Username:           cfg.Username,
+		Password:           cfg.Password,
+		DB:                 cfg.DB,
+		MaxRetries:         cfg.MaxRetries,
+		MinRetryBackoff:    cfg.MinRetryBackoff,
+		MaxRetryBackoff:    cfg.MaxRetryBackoff,
+		DialTimeout:        cfg.DialTimeout,
+		ReadTimeout:        cfg.ReadTimeout,
+		WriteTimeout:       cfg.WriteTimeout,
+		PoolSize:           cfg.PoolSize,
+		MinIdleConns:       cfg.MinIdleConns,
+		MaxConnAge:         cfg.MaxConnAge,
+		PoolTimeout:        cfg.PoolTimeout,
+		IdleTimeout:        cfg.IdleTimeout,
+		IdleCheckFrequency: cfg.IdleCheckFrequency,
+		TLSConfig:          cfg.TLSConfig,
+	})
+
+	if err := db.Ping(context.Background()).Err(); err != nil {
+		return nil, errRedisConnection(err)
+	}
+
+	p := &Provider{
+		keyPrefix: cfg.KeyPrefix,
+		db:        db,
 	}
 
 	return p, nil
 }
 
 func (p *Provider) getRedisSessionKey(sessionID []byte) string {
 	key := bytebufferpool.Get()
-	key.SetString(p.config.KeyPrefix)
+	key.SetString(p.keyPrefix)
 	key.WriteString(":")
 	key.Write(sessionID)
 

providers/redis/types.go

@@ -90,8 +90,99 @@ type Config struct {
 	Limiter redis.Limiter
 }
 
+// FailoverConfig provider settings.
+type FailoverConfig struct {
+	// Key prefix
+	KeyPrefix string
+
+	// Optional username.
+	Username string
+
+	// Optional password. Must match the password specified in the
+	// requirepass server configuration option.
+	Password string
+
+	// Database to be selected after connecting to the server.
+	DB int
+
+	// The sentinel master name.
+	MasterName string
+
+	// The sentinel nodes seed list (host:port).
+	SentinelAddrs []string
+
+	// The password for the sentinel connection if required (different to username/password).
+	SentinelPassword string
+
+	// Routes read-only commands to the closest node. Only relevant with NewFailoverCluster.
+	RouteByLatency bool
+
+	// Routes read-only commands in random order. Only relevant with NewFailoverCluster.
+	RouteRandomly bool
+
+	// Route read-only commands to slave nodes.
+	SlaveOnly bool
+
+	// Maximum number of retries before giving up.
+	// Default is to not retry failed commands.
+	MaxRetries int
+
+	// Minimum backoff between each retry.
+	// Default is 8 milliseconds; -1 disables backoff.
+	MinRetryBackoff time.Duration
+
+	// Maximum backoff between each retry.
+	// Default is 512 milliseconds; -1 disables backoff.
+	MaxRetryBackoff time.Duration
+
+	// Dial timeout for establishing new connections.
+	// Default is 5 seconds.
+	DialTimeout time.Duration
+
+	// Timeout for socket reads. If reached, commands will fail
+	// with a timeout instead of blocking. Use value -1 for no timeout and 0 for default.
+	// Default is 3 seconds.
+	ReadTimeout time.Duration
+
+	// Timeout for socket writes. If reached, commands will fail
+	// with a timeout instead of blocking.
+	// Default is ReadTimeout.
+	WriteTimeout time.Duration
+
+	// Maximum number of socket connections.
+	// Default is 10 connections per every CPU as reported by runtime.NumCPU.
+	PoolSize int
+
+	// Minimum number of idle connections which is useful when establishing
+	// new connection is slow.
+	MinIdleConns int
+
+	// Connection age at which client retires (closes) the connection.
+	// Default is to not close aged connections.
+	MaxConnAge time.Duration
+
+	// Amount of time client waits for connection if all connections
+	// are busy before returning an error.
+	// Default is ReadTimeout + 1 second.
+	PoolTimeout time.Duration
+
+	// Amount of time after which client closes idle connections.
+	// Should be less than server's timeout.
+	// Default is 5 minutes. -1 disables idle timeout check.
+	IdleTimeout time.Duration
+
+	// Frequency of idle checks made by idle connections reaper.
+	// Default is 1 minute. -1 disables idle connections reaper,
+	// but idle connections are still discarded by the client
+	// if IdleTimeout is set.
+	IdleCheckFrequency time.Duration
+
+	// TLS Config to use. When set TLS will be negotiated.
+	TLSConfig *tls.Config
+}
+
 // Provider backend manager
 type Provider struct {
-	config Config
-	db     *redis.Client
+	keyPrefix string
+	db        redis.Cmdable
 }