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redis.go
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redis.go
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package peer
import (
"context"
"crypto/tls"
"errors"
"fmt"
"net"
"os"
"sort"
"strings"
"sync"
"time"
"github.com/opsramp/tracing-proxy/pkg/libtrace/transmission"
"github.com/gomodule/redigo/redis"
"github.com/opsramp/tracing-proxy/config"
"github.com/opsramp/tracing-proxy/internal/redimem"
"github.com/sirupsen/logrus"
)
const (
// refreshCacheInterval is how frequently this host will re-register itself
// with Redis. This should happen about 3x during each timeout phase in order
// to allow multiple timeouts to fail and yet still keep the host in the mix.
// Falling out of Redis will result in re-hashing the host-trace afinity and
// will cause broken traces for those that fall on both sides of the rehashing.
// This is why it's important to ensure hosts stay in the pool.
refreshCacheInterval = 3 * time.Second
// peerEntryTimeout is how long redis will wait before expiring a peer that
// doesn't check in. The ratio of refresh to peer timout should be 1/3. Redis
// timeouts are in seconds and entries can last up to 2 seconds longer than
// their expected timeout (in my load testing), so the lower bound for this
// timer should be ... 5sec?
peerEntryTimeout = 10 * time.Second
)
type redisPeers struct {
store *redimem.RedisMembership
peers []string
peerLock sync.Mutex
c config.Config
callbacks []func()
publicAddr string
}
// NewRedisPeers returns a peers collection backed by redis
func newRedisPeers(ctx context.Context, c config.Config, done chan struct{}) (Peers, error) {
redisHost, _ := c.GetRedisHost()
if redisHost == "" {
redisHost = "localhost:6379"
}
options := buildOptions(c)
pool := &redis.Pool{
MaxIdle: 3,
MaxActive: 30,
IdleTimeout: 5 * time.Minute,
Wait: true,
Dial: func() (redis.Conn, error) {
// if redis is started at the same time as tracing-proxy, connecting to redis can
// fail and cause tracing-proxy to error out.
// Instead, we will try to connect to redis for up to 10 seconds with
// a 1 second delay between attempts to allow the redis process to init
var (
conn redis.Conn
err error
)
for timeout := time.After(10 * time.Second); ; {
select {
case <-timeout:
return nil, err
default:
conn, err = redis.Dial("tcp", redisHost, options...)
if err == nil {
return conn, nil
}
time.Sleep(time.Second)
}
}
},
}
// deal with this error
address, err := publicAddr(c)
if err != nil {
return nil, err
}
peers := &redisPeers{
store: &redimem.RedisMembership{
Prefix: c.GetRedisPrefix(),
Pool: pool,
},
peers: make([]string, 1),
c: c,
callbacks: []func(){},
publicAddr: address,
}
// register myself once
if !c.IsTest() {
for !transmission.DefaultAvailability.Status() {
logrus.Info("peer is not available yet")
time.Sleep(5 * time.Second)
}
}
err = peers.store.Register(ctx, address, peerEntryTimeout)
if err != nil {
logrus.WithError(err).Errorf("failed to register self with redis peer store")
return nil, err
}
// go establish a regular registration heartbeat to ensure I stay alive in redis
go peers.registerSelf(done)
// get our peer list once to seed ourselves
peers.updatePeerListOnce()
// go watch the list of peers and trigger callbacks whenever it changes.
// populate my local list of peers so each request can hit memory and only hit
// redis on a ticker
go peers.watchPeers(done)
return peers, nil
}
func (p *redisPeers) GetPeers() ([]string, error) {
p.peerLock.Lock()
defer p.peerLock.Unlock()
retList := make([]string, len(p.peers))
copy(retList, p.peers)
return retList, nil
}
func (p *redisPeers) RegisterUpdatedPeersCallback(cb func()) {
p.callbacks = append(p.callbacks, cb)
}
// registerSelf inserts self into the peer list and updates self's entry on a
// regular basis so it doesn't time out and get removed from the list of peers.
// When this function stops, it tries to remove the registered key.
func (p *redisPeers) registerSelf(done chan struct{}) {
tk := time.NewTicker(refreshCacheInterval)
for {
select {
case <-tk.C:
if !transmission.DefaultAvailability.Status() {
continue
}
ctx, cancel := context.WithTimeout(context.Background(), p.c.GetPeerTimeout())
err := p.store.Register(ctx, p.publicAddr, peerEntryTimeout)
if err != nil {
logrus.WithField("name", p.publicAddr).
WithField("timeoutSec", peerEntryTimeout).
WithField("err", err).
Error("registration failed")
}
cancel()
case <-done:
// unregister ourselves
ctx, cancel := context.WithTimeout(context.Background(), p.c.GetPeerTimeout())
err := p.store.Unregister(ctx, p.publicAddr)
if err != nil {
logrus.WithField("name", p.publicAddr).
WithField("err", err).
Error("unregister failed")
}
cancel()
return
}
}
}
func (p *redisPeers) updatePeerListOnce() {
ctx, cancel := context.WithTimeout(context.Background(), p.c.GetPeerTimeout())
defer cancel()
currentPeers, err := p.store.GetMembers(ctx)
if err != nil {
logrus.WithError(err).
WithFields(logrus.Fields{
"name": p.publicAddr,
"timeout": p.c.GetPeerTimeout().String(),
}).
Error("get members failed")
return
}
sort.Strings(currentPeers)
// update peer list and trigger callbacks saying the peer list has changed
p.peerLock.Lock()
defer p.peerLock.Unlock()
p.peers = currentPeers
}
func (p *redisPeers) watchPeers(done chan struct{}) {
oldPeerList := p.peers
sort.Strings(oldPeerList)
tk := time.NewTicker(refreshCacheInterval)
for {
select {
case <-tk.C:
ctx, cancel := context.WithTimeout(context.Background(), p.c.GetPeerTimeout())
currentPeers, err := p.store.GetMembers(ctx)
cancel()
if err != nil {
logrus.WithError(err).
WithFields(logrus.Fields{
"name": p.publicAddr,
"timeout": p.c.GetPeerTimeout().String(),
"oldPeers": oldPeerList,
}).
Error("get members failed during watch")
continue
}
sort.Strings(currentPeers)
if !equal(oldPeerList, currentPeers) {
// update peer list and trigger callbacks saying the peer list has changed
p.peerLock.Lock()
p.peers = currentPeers
oldPeerList = currentPeers
p.peerLock.Unlock()
for _, callback := range p.callbacks {
// don't block on any of the callbacks.
go callback()
}
}
case <-done:
p.peerLock.Lock()
p.peers = []string{}
p.peerLock.Unlock()
return
}
}
}
func buildOptions(c config.Config) []redis.DialOption {
options := []redis.DialOption{
redis.DialReadTimeout(1 * time.Second),
redis.DialConnectTimeout(1 * time.Second),
redis.DialDatabase(c.GetRedisDatabase()),
}
username, _ := c.GetRedisUsername()
if username != "" {
options = append(options, redis.DialUsername(username))
}
password, _ := c.GetRedisPassword()
if password != "" {
options = append(options, redis.DialPassword(password))
}
useTLS, _ := c.GetUseTLS()
tlsInsecure, _ := c.GetUseTLSInsecure()
if useTLS {
tlsConfig := &tls.Config{
MinVersion: tls.VersionTLS12,
}
if tlsInsecure {
tlsConfig.InsecureSkipVerify = true
}
options = append(options,
redis.DialTLSConfig(tlsConfig),
redis.DialUseTLS(useTLS))
}
return options
}
func publicAddr(c config.Config) (string, error) {
// compute the public version of my peer listen address
listenAddr, _ := c.GetGRPCPeerListenAddr()
_, port, err := net.SplitHostPort(listenAddr)
if err != nil {
return "", err
}
var myIdentifier string
// If RedisIdentifier is set, use as identifier.
if redisIdentifier, _ := c.GetRedisIdentifier(); redisIdentifier != "" {
myIdentifier = redisIdentifier
logrus.WithField("identifier", myIdentifier).Info("using specified RedisIdentifier from config")
} else {
// Otherwise, determine idenntifier from network interface.
myIdentifier, err = getIdentifierFromInterfaces(c)
if err != nil {
return "", err
}
}
publicListenAddr := fmt.Sprintf("http://%s:%s", myIdentifier, port)
return publicListenAddr, nil
}
// Scan network interfaces to determine an identifier from either IP or hostname.
func getIdentifierFromInterfaces(c config.Config) (string, error) {
myIdentifier, _ := os.Hostname()
identifierInterfaceName, _ := c.GetIdentifierInterfaceName()
if identifierInterfaceName != "" {
ifc, err := net.InterfaceByName(identifierInterfaceName)
if err != nil {
logrus.WithError(err).WithField("interface", identifierInterfaceName).
Error("IdentifierInterfaceName set but couldn't find interface by that name")
return "", err
}
addrs, err := ifc.Addrs()
if err != nil {
logrus.WithError(err).WithField("interface", identifierInterfaceName).
Error("IdentifierInterfaceName set but couldn't list addresses")
return "", err
}
var ipStr string
for _, addr := range addrs {
// ParseIP doesn't know what to do with the suffix
ip := net.ParseIP(strings.Split(addr.String(), "/")[0])
ipv6, _ := c.GetUseIPV6Identifier()
if ipv6 && ip.To16() != nil {
ipStr = fmt.Sprintf("[%s]", ip.String())
break
}
if !ipv6 && ip.To4() != nil {
ipStr = ip.String()
break
}
}
if ipStr == "" {
err = errors.New("could not find a valid IP to use from interface")
logrus.WithField("interface", ifc.Name).WithError(err)
return "", err
}
myIdentifier = ipStr
logrus.WithField("identifier", myIdentifier).WithField("interface", ifc.Name).Info("using identifier from interface")
}
return myIdentifier, nil
}
// equal tells whether a and b contain the same elements.
// A nil argument is equivalent to an empty slice.
// lifted from https://yourbasic.org/golang/compare-slices/
func equal(a, b []string) bool {
if len(a) != len(b) {
return false
}
for i, v := range a {
if v != b[i] {
return false
}
}
return true
}