File 0003-Support-external-redis-sentinel-cluster.patch of Package docker-distribution
From 3ccdcfc14c70d0993e3a822590e1091836320549 Mon Sep 17 00:00:00 2001
From: Jeremy Xu <jeremyxu2010@gmail.com>
Date: Sun, 24 Mar 2019 13:46:35 +0800
Subject: [PATCH] support external redis sentinel cluster
Signed-off-by: Jeremy Xu <jeremyxu2010@gmail.com>
---
configuration/configuration.go | 3 +
registry/handlers/app.go | 65 ++-
registry/handlers/app_test.go | 57 ++-
vendor.conf | 1 +
vendor/github.com/FZambia/sentinel/LICENSE | 201 +++++++++
vendor/github.com/FZambia/sentinel/README.md | 39 ++
.../github.com/FZambia/sentinel/sentinel.go | 426 ++++++++++++++++++
7 files changed, 777 insertions(+), 15 deletions(-)
create mode 100644 vendor/github.com/FZambia/sentinel/LICENSE
create mode 100644 vendor/github.com/FZambia/sentinel/README.md
create mode 100644 vendor/github.com/FZambia/sentinel/sentinel.go
diff --git a/configuration/configuration.go b/configuration/configuration.go
index 34884dd2c..fb1c63879 100644
--- a/configuration/configuration.go
+++ b/configuration/configuration.go
@@ -165,6 +165,9 @@ type Configuration struct {
// Addr specifies the the redis instance available to the application.
Addr string `yaml:"addr,omitempty"`
+ // SentinelMasterSet specifies the the redis sentinel master set name.
+ SentinelMasterSet string `yaml:"sentinelMasterSet,omitempty"`
+
// Password string to use when making a connection.
Password string `yaml:"password,omitempty"`
diff --git a/registry/handlers/app.go b/registry/handlers/app.go
index 057e4e4e8..62fba3fa9 100644
--- a/registry/handlers/app.go
+++ b/registry/handlers/app.go
@@ -3,6 +3,7 @@ package handlers
import (
"context"
cryptorand "crypto/rand"
+ "errors"
"expvar"
"fmt"
"math/rand"
@@ -15,6 +16,8 @@ import (
"strings"
"time"
+ "github.com/FZambia/sentinel"
+
"github.com/docker/distribution"
"github.com/docker/distribution/configuration"
dcontext "github.com/docker/distribution/context"
@@ -24,7 +27,7 @@ import (
"github.com/docker/distribution/notifications"
"github.com/docker/distribution/reference"
"github.com/docker/distribution/registry/api/errcode"
- "github.com/docker/distribution/registry/api/v2"
+ v2 "github.com/docker/distribution/registry/api/v2"
"github.com/docker/distribution/registry/auth"
registrymiddleware "github.com/docker/distribution/registry/middleware/registry"
repositorymiddleware "github.com/docker/distribution/registry/middleware/repository"
@@ -498,6 +501,44 @@ func (app *App) configureRedis(configuration *configuration.Configuration) {
return
}
+ var getRedisAddr func() (string, error)
+ var testOnBorrow func(c redis.Conn, t time.Time) error
+ if configuration.Redis.SentinelMasterSet != "" {
+ sntnl := &sentinel.Sentinel{
+ Addrs: strings.Split(configuration.Redis.Addr, ","),
+ MasterName: configuration.Redis.SentinelMasterSet,
+ Dial: func(addr string) (redis.Conn, error) {
+ c, err := redis.DialTimeout("tcp", addr,
+ configuration.Redis.DialTimeout,
+ configuration.Redis.ReadTimeout,
+ configuration.Redis.WriteTimeout)
+ if err != nil {
+ return nil, err
+ }
+ return c, nil
+ },
+ }
+ getRedisAddr = func() (string, error) {
+ return sntnl.MasterAddr()
+ }
+ testOnBorrow = func(c redis.Conn, t time.Time) error {
+ if !sentinel.TestRole(c, "master") {
+ return errors.New("role check failed")
+ }
+ return nil
+ }
+
+ } else {
+ getRedisAddr = func() (string, error) {
+ return configuration.Redis.Addr, nil
+ }
+ testOnBorrow = func(c redis.Conn, t time.Time) error {
+ // TODO(stevvooe): We can probably do something more interesting
+ // here with the health package.
+ _, err := c.Do("PING")
+ return err
+ }
+ }
pool := &redis.Pool{
Dial: func() (redis.Conn, error) {
// TODO(stevvooe): Yet another use case for contextual timing.
@@ -513,8 +554,11 @@ func (app *App) configureRedis(configuration *configuration.Configuration) {
}
}
- conn, err := redis.DialTimeout("tcp",
- configuration.Redis.Addr,
+ redisAddr, err := getRedisAddr()
+ if err != nil {
+ return nil, err
+ }
+ conn, err := redis.DialTimeout("tcp", redisAddr,
configuration.Redis.DialTimeout,
configuration.Redis.ReadTimeout,
configuration.Redis.WriteTimeout)
@@ -546,16 +590,11 @@ func (app *App) configureRedis(configuration *configuration.Configuration) {
done(nil)
return conn, nil
},
- MaxIdle: configuration.Redis.Pool.MaxIdle,
- MaxActive: configuration.Redis.Pool.MaxActive,
- IdleTimeout: configuration.Redis.Pool.IdleTimeout,
- TestOnBorrow: func(c redis.Conn, t time.Time) error {
- // TODO(stevvooe): We can probably do something more interesting
- // here with the health package.
- _, err := c.Do("PING")
- return err
- },
- Wait: false, // if a connection is not available, proceed without cache.
+ MaxIdle: configuration.Redis.Pool.MaxIdle,
+ MaxActive: configuration.Redis.Pool.MaxActive,
+ IdleTimeout: configuration.Redis.Pool.IdleTimeout,
+ TestOnBorrow: testOnBorrow,
+ Wait: false, // if a connection is not available, proceed without cache.
}
app.redis = pool
diff --git a/registry/handlers/app_test.go b/registry/handlers/app_test.go
index f95b441f9..602e98705 100644
--- a/registry/handlers/app_test.go
+++ b/registry/handlers/app_test.go
@@ -11,7 +11,7 @@ import (
"github.com/docker/distribution/configuration"
"github.com/docker/distribution/context"
"github.com/docker/distribution/registry/api/errcode"
- "github.com/docker/distribution/registry/api/v2"
+ v2 "github.com/docker/distribution/registry/api/v2"
"github.com/docker/distribution/registry/auth"
_ "github.com/docker/distribution/registry/auth/silly"
"github.com/docker/distribution/registry/storage"
@@ -140,7 +140,29 @@ func TestAppDispatcher(t *testing.T) {
// TestNewApp covers the creation of an application via NewApp with a
// configuration.
func TestNewApp(t *testing.T) {
- ctx := context.Background()
+
+ config := configuration.Configuration{
+ Storage: configuration.Storage{
+ "testdriver": nil,
+ "maintenance": configuration.Parameters{"uploadpurging": map[interface{}]interface{}{
+ "enabled": false,
+ }},
+ },
+ Auth: configuration.Auth{
+ // For now, we simply test that new auth results in a viable
+ // application.
+ "silly": {
+ "realm": "realm-test",
+ "service": "service-test",
+ },
+ },
+ }
+ runAppWithConfig(t, config)
+}
+
+// TestNewApp covers the creation of an application via NewApp with a
+// configuration(with redis).
+func TestNewAppWithRedis(t *testing.T) {
config := configuration.Configuration{
Storage: configuration.Storage{
"testdriver": nil,
@@ -157,7 +179,38 @@ func TestNewApp(t *testing.T) {
},
},
}
+ config.Redis.Addr = "127.0.0.1:6379"
+ config.Redis.DB = 0
+ runAppWithConfig(t, config)
+}
+// TestNewApp covers the creation of an application via NewApp with a
+// configuration(with redis sentinel cluster).
+func TestNewAppWithRedisSentinelCluster(t *testing.T) {
+ config := configuration.Configuration{
+ Storage: configuration.Storage{
+ "testdriver": nil,
+ "maintenance": configuration.Parameters{"uploadpurging": map[interface{}]interface{}{
+ "enabled": false,
+ }},
+ },
+ Auth: configuration.Auth{
+ // For now, we simply test that new auth results in a viable
+ // application.
+ "silly": {
+ "realm": "realm-test",
+ "service": "service-test",
+ },
+ },
+ }
+ config.Redis.Addr = "192.168.0.11:26379,192.168.0.12:26379"
+ config.Redis.DB = 0
+ config.Redis.SentinelMasterSet = "mymaster"
+ runAppWithConfig(t, config)
+}
+
+func runAppWithConfig(t *testing.T, config configuration.Configuration) {
+ ctx := context.Background()
// Mostly, with this test, given a sane configuration, we are simply
// ensuring that NewApp doesn't panic. We might want to tweak this
// behavior.
diff --git a/vendor.conf b/vendor.conf
index 12f71672f..0baad5561 100644
--- a/vendor.conf
+++ b/vendor.conf
@@ -49,3 +49,4 @@ gopkg.in/yaml.v2 v2.2.1
rsc.io/letsencrypt e770c10b0f1a64775ae91d240407ce00d1a5bdeb https://github.com/dmcgowan/letsencrypt.git
github.com/opencontainers/go-digest a6d0ee40d4207ea02364bd3b9e8e77b9159ba1eb
github.com/opencontainers/image-spec ab7389ef9f50030c9b245bc16b981c7ddf192882
+github.com/FZambia/sentinel 5585739eb4b6478aa30161866ccf9ce0ef5847c7 https://github.com/jeremyxu2010/sentinel.git
diff --git a/vendor/github.com/FZambia/sentinel/LICENSE b/vendor/github.com/FZambia/sentinel/LICENSE
new file mode 100644
index 000000000..8dada3eda
--- /dev/null
+++ b/vendor/github.com/FZambia/sentinel/LICENSE
@@ -0,0 +1,201 @@
+ Apache License
+ Version 2.0, January 2004
+ http://www.apache.org/licenses/
+
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+
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+ 7. Disclaimer of Warranty. Unless required by applicable law or
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+ whether in tort (including negligence), contract, or otherwise,
+ unless required by applicable law (such as deliberate and grossly
+ negligent acts) or agreed to in writing, shall any Contributor be
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+ defend, and hold each Contributor harmless for any liability
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diff --git a/vendor/github.com/FZambia/sentinel/README.md b/vendor/github.com/FZambia/sentinel/README.md
new file mode 100644
index 000000000..f544c54ef
--- /dev/null
+++ b/vendor/github.com/FZambia/sentinel/README.md
@@ -0,0 +1,39 @@
+go-sentinel
+===========
+
+Redis Sentinel support for [redigo](https://github.com/gomodule/redigo) library.
+
+Documentation
+-------------
+
+- [API Reference](http://godoc.org/github.com/FZambia/sentinel)
+
+Alternative solution
+--------------------
+
+You can alternatively configure Haproxy between your application and Redis to proxy requests to Redis master instance if you only need HA:
+
+```
+listen redis
+ server redis-01 127.0.0.1:6380 check port 6380 check inter 2s weight 1 inter 2s downinter 5s rise 10 fall 2
+ server redis-02 127.0.0.1:6381 check port 6381 check inter 2s weight 1 inter 2s downinter 5s rise 10 fall 2 backup
+ bind *:6379
+ mode tcp
+ option tcpka
+ option tcplog
+ option tcp-check
+ tcp-check send PING\r\n
+ tcp-check expect string +PONG
+ tcp-check send info\ replication\r\n
+ tcp-check expect string role:master
+ tcp-check send QUIT\r\n
+ tcp-check expect string +OK
+ balance roundrobin
+```
+
+This way you don't need to use this library.
+
+License
+-------
+
+Library is available under the [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.html).
diff --git a/vendor/github.com/FZambia/sentinel/sentinel.go b/vendor/github.com/FZambia/sentinel/sentinel.go
new file mode 100644
index 000000000..79209e9f0
--- /dev/null
+++ b/vendor/github.com/FZambia/sentinel/sentinel.go
@@ -0,0 +1,426 @@
+package sentinel
+
+import (
+ "errors"
+ "fmt"
+ "net"
+ "strings"
+ "sync"
+ "time"
+
+ "github.com/garyburd/redigo/redis"
+)
+
+// Sentinel provides a way to add high availability (HA) to Redis Pool using
+// preconfigured addresses of Sentinel servers and name of master which Sentinels
+// monitor. It works with Redis >= 2.8.12 (mostly because of ROLE command that
+// was introduced in that version, it's possible though to support old versions
+// using INFO command).
+//
+// Example of the simplest usage to contact master "mymaster":
+//
+// func newSentinelPool() *redis.Pool {
+// sntnl := &sentinel.Sentinel{
+// Addrs: []string{":26379", ":26380", ":26381"},
+// MasterName: "mymaster",
+// Dial: func(addr string) (redis.Conn, error) {
+// timeout := 500 * time.Millisecond
+// c, err := redis.DialTimeout("tcp", addr, timeout, timeout, timeout)
+// if err != nil {
+// return nil, err
+// }
+// return c, nil
+// },
+// }
+// return &redis.Pool{
+// MaxIdle: 3,
+// MaxActive: 64,
+// Wait: true,
+// IdleTimeout: 240 * time.Second,
+// Dial: func() (redis.Conn, error) {
+// masterAddr, err := sntnl.MasterAddr()
+// if err != nil {
+// return nil, err
+// }
+// c, err := redis.Dial("tcp", masterAddr)
+// if err != nil {
+// return nil, err
+// }
+// return c, nil
+// },
+// TestOnBorrow: func(c redis.Conn, t time.Time) error {
+// if !sentinel.TestRole(c, "master") {
+// return errors.New("Role check failed")
+// } else {
+// return nil
+// }
+// },
+// }
+// }
+type Sentinel struct {
+ // Addrs is a slice with known Sentinel addresses.
+ Addrs []string
+
+ // MasterName is a name of Redis master Sentinel servers monitor.
+ MasterName string
+
+ // Dial is a user supplied function to connect to Sentinel on given address. This
+ // address will be chosen from Addrs slice.
+ // Note that as per the redis-sentinel client guidelines, a timeout is mandatory
+ // while connecting to Sentinels, and should not be set to 0.
+ Dial func(addr string) (redis.Conn, error)
+
+ // Pool is a user supplied function returning custom connection pool to Sentinel.
+ // This can be useful to tune options if you are not satisfied with what default
+ // Sentinel pool offers. See defaultPool() method for default pool implementation.
+ // In most cases you only need to provide Dial function and let this be nil.
+ Pool func(addr string) *redis.Pool
+
+ mu sync.RWMutex
+ pools map[string]*redis.Pool
+ addr string
+}
+
+// NoSentinelsAvailable is returned when all sentinels in the list are exhausted
+// (or none configured), and contains the last error returned by Dial (which
+// may be nil)
+type NoSentinelsAvailable struct {
+ lastError error
+}
+
+func (ns NoSentinelsAvailable) Error() string {
+ if ns.lastError != nil {
+ return fmt.Sprintf("redigo: no sentinels available; last error: %s", ns.lastError.Error())
+ }
+ return fmt.Sprintf("redigo: no sentinels available")
+}
+
+// putToTop puts Sentinel address to the top of address list - this means
+// that all next requests will use Sentinel on this address first.
+//
+// From Sentinel guidelines:
+//
+// The first Sentinel replying to the client request should be put at the
+// start of the list, so that at the next reconnection, we'll try first
+// the Sentinel that was reachable in the previous connection attempt,
+// minimizing latency.
+//
+// Lock must be held by caller.
+func (s *Sentinel) putToTop(addr string) {
+ addrs := s.Addrs
+ if addrs[0] == addr {
+ // Already on top.
+ return
+ }
+ newAddrs := []string{addr}
+ for _, a := range addrs {
+ if a == addr {
+ continue
+ }
+ newAddrs = append(newAddrs, a)
+ }
+ s.Addrs = newAddrs
+}
+
+// putToBottom puts Sentinel address to the bottom of address list.
+// We call this method internally when see that some Sentinel failed to answer
+// on application request so next time we start with another one.
+//
+// Lock must be held by caller.
+func (s *Sentinel) putToBottom(addr string) {
+ addrs := s.Addrs
+ if addrs[len(addrs)-1] == addr {
+ // Already on bottom.
+ return
+ }
+ newAddrs := []string{}
+ for _, a := range addrs {
+ if a == addr {
+ continue
+ }
+ newAddrs = append(newAddrs, a)
+ }
+ newAddrs = append(newAddrs, addr)
+ s.Addrs = newAddrs
+}
+
+// defaultPool returns a connection pool to one Sentinel. This allows
+// us to call concurrent requests to Sentinel using connection Do method.
+func (s *Sentinel) defaultPool(addr string) *redis.Pool {
+ return &redis.Pool{
+ MaxIdle: 3,
+ MaxActive: 10,
+ Wait: true,
+ IdleTimeout: 240 * time.Second,
+ Dial: func() (redis.Conn, error) {
+ return s.Dial(addr)
+ },
+ TestOnBorrow: func(c redis.Conn, t time.Time) error {
+ _, err := c.Do("PING")
+ return err
+ },
+ }
+}
+
+func (s *Sentinel) get(addr string) redis.Conn {
+ pool := s.poolForAddr(addr)
+ return pool.Get()
+}
+
+func (s *Sentinel) poolForAddr(addr string) *redis.Pool {
+ s.mu.Lock()
+ if s.pools == nil {
+ s.pools = make(map[string]*redis.Pool)
+ }
+ pool, ok := s.pools[addr]
+ if ok {
+ s.mu.Unlock()
+ return pool
+ }
+ s.mu.Unlock()
+ newPool := s.newPool(addr)
+ s.mu.Lock()
+ p, ok := s.pools[addr]
+ if ok {
+ s.mu.Unlock()
+ return p
+ }
+ s.pools[addr] = newPool
+ s.mu.Unlock()
+ return newPool
+}
+
+func (s *Sentinel) newPool(addr string) *redis.Pool {
+ if s.Pool != nil {
+ return s.Pool(addr)
+ }
+ return s.defaultPool(addr)
+}
+
+// close connection pool to Sentinel.
+// Lock must be hold by caller.
+func (s *Sentinel) close() {
+ if s.pools != nil {
+ for _, pool := range s.pools {
+ pool.Close()
+ }
+ }
+ s.pools = nil
+}
+
+func (s *Sentinel) doUntilSuccess(f func(redis.Conn) (interface{}, error)) (interface{}, error) {
+ s.mu.RLock()
+ addrs := s.Addrs
+ s.mu.RUnlock()
+
+ var lastErr error
+
+ for _, addr := range addrs {
+ conn := s.get(addr)
+ reply, err := f(conn)
+ conn.Close()
+ if err != nil {
+ lastErr = err
+ s.mu.Lock()
+ pool, ok := s.pools[addr]
+ if ok {
+ pool.Close()
+ delete(s.pools, addr)
+ }
+ s.putToBottom(addr)
+ s.mu.Unlock()
+ continue
+ }
+ s.putToTop(addr)
+ return reply, nil
+ }
+
+ return nil, NoSentinelsAvailable{lastError: lastErr}
+}
+
+// MasterAddr returns an address of current Redis master instance.
+func (s *Sentinel) MasterAddr() (string, error) {
+ res, err := s.doUntilSuccess(func(c redis.Conn) (interface{}, error) {
+ return queryForMaster(c, s.MasterName)
+ })
+ if err != nil {
+ return "", err
+ }
+ return res.(string), nil
+}
+
+// SlaveAddrs returns a slice with known slave addresses of current master instance.
+func (s *Sentinel) SlaveAddrs() ([]string, error) {
+ res, err := s.doUntilSuccess(func(c redis.Conn) (interface{}, error) {
+ return queryForSlaveAddrs(c, s.MasterName)
+ })
+ if err != nil {
+ return nil, err
+ }
+ return res.([]string), nil
+}
+
+// Slave represents a Redis slave instance which is known by Sentinel.
+type Slave struct {
+ ip string
+ port string
+ flags string
+}
+
+// Addr returns an address of slave.
+func (s *Slave) Addr() string {
+ return net.JoinHostPort(s.ip, s.port)
+}
+
+// Available returns if slave is in working state at moment based on information in slave flags.
+func (s *Slave) Available() bool {
+ return !strings.Contains(s.flags, "disconnected") && !strings.Contains(s.flags, "s_down")
+}
+
+// Slaves returns a slice with known slaves of master instance.
+func (s *Sentinel) Slaves() ([]*Slave, error) {
+ res, err := s.doUntilSuccess(func(c redis.Conn) (interface{}, error) {
+ return queryForSlaves(c, s.MasterName)
+ })
+ if err != nil {
+ return nil, err
+ }
+ return res.([]*Slave), nil
+}
+
+// SentinelAddrs returns a slice of known Sentinel addresses Sentinel server aware of.
+func (s *Sentinel) SentinelAddrs() ([]string, error) {
+ res, err := s.doUntilSuccess(func(c redis.Conn) (interface{}, error) {
+ return queryForSentinels(c, s.MasterName)
+ })
+ if err != nil {
+ return nil, err
+ }
+ return res.([]string), nil
+}
+
+// Discover allows to update list of known Sentinel addresses. From docs:
+//
+// A client may update its internal list of Sentinel nodes following this procedure:
+// 1) Obtain a list of other Sentinels for this master using the command SENTINEL sentinels <master-name>.
+// 2) Add every ip:port pair not already existing in our list at the end of the list.
+func (s *Sentinel) Discover() error {
+ addrs, err := s.SentinelAddrs()
+ if err != nil {
+ return err
+ }
+ s.mu.Lock()
+ for _, addr := range addrs {
+ if !stringInSlice(addr, s.Addrs) {
+ s.Addrs = append(s.Addrs, addr)
+ }
+ }
+ s.mu.Unlock()
+ return nil
+}
+
+// Close closes current connection to Sentinel.
+func (s *Sentinel) Close() error {
+ s.mu.Lock()
+ s.close()
+ s.mu.Unlock()
+ return nil
+}
+
+// TestRole wraps GetRole in a test to verify if the role matches an expected
+// role string. If there was any error in querying the supplied connection,
+// the function returns false. Works with Redis >= 2.8.12.
+// It's not goroutine safe, but if you call this method on pooled connections
+// then you are OK.
+func TestRole(c redis.Conn, expectedRole string) bool {
+ role, err := getRole(c)
+ if err != nil || role != expectedRole {
+ return false
+ }
+ return true
+}
+
+// getRole is a convenience function supplied to query an instance (master or
+// slave) for its role. It attempts to use the ROLE command introduced in
+// redis 2.8.12.
+func getRole(c redis.Conn) (string, error) {
+ res, err := c.Do("ROLE")
+ if err != nil {
+ return "", err
+ }
+ rres, ok := res.([]interface{})
+ if ok {
+ return redis.String(rres[0], nil)
+ }
+ return "", errors.New("redigo: can not transform ROLE reply to string")
+}
+
+func queryForMaster(conn redis.Conn, masterName string) (string, error) {
+ res, err := redis.Strings(conn.Do("SENTINEL", "get-master-addr-by-name", masterName))
+ if err != nil {
+ return "", err
+ }
+ if len(res) < 2 {
+ return "", errors.New("redigo: malformed get-master-addr-by-name reply")
+ }
+ masterAddr := net.JoinHostPort(res[0], res[1])
+ return masterAddr, nil
+}
+
+func queryForSlaveAddrs(conn redis.Conn, masterName string) ([]string, error) {
+ slaves, err := queryForSlaves(conn, masterName)
+ if err != nil {
+ return nil, err
+ }
+ slaveAddrs := make([]string, 0)
+ for _, slave := range slaves {
+ slaveAddrs = append(slaveAddrs, slave.Addr())
+ }
+ return slaveAddrs, nil
+}
+
+func queryForSlaves(conn redis.Conn, masterName string) ([]*Slave, error) {
+ res, err := redis.Values(conn.Do("SENTINEL", "slaves", masterName))
+ if err != nil {
+ return nil, err
+ }
+ slaves := make([]*Slave, 0)
+ for _, a := range res {
+ sm, err := redis.StringMap(a, err)
+ if err != nil {
+ return slaves, err
+ }
+ slave := &Slave{
+ ip: sm["ip"],
+ port: sm["port"],
+ flags: sm["flags"],
+ }
+ slaves = append(slaves, slave)
+ }
+ return slaves, nil
+}
+
+func queryForSentinels(conn redis.Conn, masterName string) ([]string, error) {
+ res, err := redis.Values(conn.Do("SENTINEL", "sentinels", masterName))
+ if err != nil {
+ return nil, err
+ }
+ sentinels := make([]string, 0)
+ for _, a := range res {
+ sm, err := redis.StringMap(a, err)
+ if err != nil {
+ return sentinels, err
+ }
+ sentinels = append(sentinels, fmt.Sprintf("%s:%s", sm["ip"], sm["port"]))
+ }
+ return sentinels, nil
+}
+
+func stringInSlice(str string, slice []string) bool {
+ for _, s := range slice {
+ if s == str {
+ return true
+ }
+ }
+ return false
+}
