Merge pull request #58 from honeycombio/travis.redis-ip

[redis] allow IP and other host identifiers

config.toml

@@ -55,6 +55,27 @@ Peers = [
 # Not eligible for live reload.
 RedisHost = "localhost:6379"
 
+# IdentifierInterfaceName is optional. By default, when using RedisHost, samproxy will use
+# the local hostname to identify itself to other peers in Redis. If your environment
+# requires that you use IPs as identifiers (for example, if peers can't resolve eachother
+# by name), you can specify the network interface that samproxy is listening on here.
+# Samproxy will use the first unicast address that it finds on the specified network
+# interface as its identifier.
+# Not eligible for live reload.
+# IdentifierInterfaceName = "eth0"
+
+# UseIPV6Identifier is optional. If using IdentifierInterfaceName, samproxy will default to the first
+# IPv4 unicast address it finds for the specified interface. If UseIPV6Identifier is used, will use
+# the first IPV6 unicast address found.
+# UseIPV6Identifier = false
+
+# RedisIdentifier is optional. By default, when using RedisHost, samproxy will use
+# the local hostname to identify itself to other peers in Redis. If your environment
+# requires that you use IPs as identifiers (for example, if peers can't resolve eachother
+# by name), you can specify the exact identifier (IP address, etc) to use here.
+# Not eligible for live reload. Overrides IdentifierInterfaceName, if both are set.
+# RedisIdentifier = "192.168.1.1"
+
 # HoneycombAPI is the URL for the upstream Honeycomb API.
 # Eligible for live reload.
 HoneycombAPI = "https://api.honeycomb.io"

config/fileconfig.go

@@ -15,23 +15,26 @@ type FileConfig struct {
 }
 
 type confContents struct {
-	ListenAddr           string
-	PeerListenAddr       string
-	APIKeys              []string
-	Peers                []string
-	RedisHost            string
-	HoneycombAPI         string
-	CollectCacheCapacity int
-	Logger               string
-	LoggingLevel         string
-	Collector            string
-	Sampler              string
-	Metrics              string
-	SendDelay            int
-	SpanSeenDelay        int
-	TraceTimeout         int
-	UpstreamBufferSize   int
-	PeerBufferSize       int
+	ListenAddr              string
+	PeerListenAddr          string
+	APIKeys                 []string
+	Peers                   []string
+	RedisHost               string
+	RedisIdentifier         string
+	IdentifierInterfaceName string
+	UseIPV6Identifier       bool
+	HoneycombAPI            string
+	CollectCacheCapacity    int
+	Logger                  string
+	LoggingLevel            string
+	Collector               string
+	Sampler                 string
+	Metrics                 string
+	SendDelay               int
+	SpanSeenDelay           int
+	TraceTimeout            int
+	UpstreamBufferSize      int
+	PeerBufferSize          int
 }
 
 // Used to marshall in the sampler type in SamplerConfig definitions
@@ -99,6 +102,18 @@ func (f *FileConfig) GetRedisHost() (string, error) {
 	return f.conf.RedisHost, nil
 }
 
+func (f *FileConfig) GetIdentifierInterfaceName() (string, error) {
+	return f.conf.IdentifierInterfaceName, nil
+}
+
+func (f *FileConfig) GetUseIPV6Identifier() (bool, error) {
+	return f.conf.UseIPV6Identifier, nil
+}
+
+func (f *FileConfig) GetRedisIdentifier() (string, error) {
+	return f.conf.RedisIdentifier, nil
+}
+
 func (f *FileConfig) GetHoneycombAPI() (string, error) {
 	return f.conf.HoneycombAPI, nil
 }

config/redis.go

@@ -3,6 +3,7 @@ package config
 import (
 	"context"
 	"fmt"
+	"net"
 	"os"
 	"sort"
 	"strings"
@@ -24,6 +25,14 @@ type RedisPeerFileConfig struct {
 	// store and check for peers
 	RedisAddress string
 
+	// If set, register the host in redis using the (first) IP address from the interface
+	// specified here. If not set, registers the host using its hostname.
+	IdentifierInterfaceName string
+
+	UseIPV6Identifier bool
+
+	RedisIdentifier string
+
 	// peers is my local cache of the peer list. It gets updated by a background
 	// ticker
 	peers []string
@@ -80,6 +89,9 @@ func (rc *RedisPeerFileConfig) Start() error {
 		}
 
 		rc.RedisAddress, _ = rc.GetRedisHost()
+		rc.IdentifierInterfaceName, _ = rc.GetIdentifierInterfaceName()
+		rc.UseIPV6Identifier, _ = rc.GetUseIPV6Identifier()
+		rc.RedisIdentifier, _ = rc.GetRedisIdentifier()
 
 		if rc.RedisAddress == "" {
 			rc.RedisAddress = "localhost:6379"
@@ -108,8 +120,47 @@ func (rc *RedisPeerFileConfig) Start() error {
 		// compute the public version of my peer listen address
 		listenAddr, _ := rc.FileConfig.GetPeerListenAddr()
 		port := strings.Split(listenAddr, ":")[1]
-		myhostname, _ := os.Hostname()
-		publicListenAddr := fmt.Sprintf("http://%s:%s", myhostname, port)
+
+		myIdentifier, _ := os.Hostname()
+		if rc.IdentifierInterfaceName != "" {
+			ifc, err := net.InterfaceByName(rc.IdentifierInterfaceName)
+			if err != nil {
+				logrus.WithError(err).WithField("interface", rc.IdentifierInterfaceName).
+					Error("IdentifierInterfaceName set but couldn't find interface by that name")
+				return
+			}
+			addrs, err := ifc.Addrs()
+			if err != nil {
+				logrus.WithError(err).WithField("interface", rc.IdentifierInterfaceName).
+					Error("IdentifierInterfaceName set but couldn't list addresses")
+				return
+			}
+			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])
+				if rc.UseIPV6Identifier && ip.To16() != nil {
+					ipStr = fmt.Sprintf("[%s]", ip.String())
+					break
+				}
+				if !rc.UseIPV6Identifier && ip.To4() != nil {
+					ipStr = ip.String()
+					break
+				}
+			}
+			if ipStr == "" {
+				logrus.WithField("interface", ifc.Name).Error("could not find a valid IP to use from interface")
+				return
+			}
+			myIdentifier = ipStr
+			logrus.WithField("identifier", myIdentifier).WithField("interface", ifc.Name).Info("using identifier from interface")
+		}
+		if rc.RedisIdentifier != "" {
+			myIdentifier = rc.RedisIdentifier
+			logrus.WithField("identifier", myIdentifier).Info("using specific identifier from config")
+		}
+
+		publicListenAddr := fmt.Sprintf("http://%s:%s", myIdentifier, port)
 		rc.publicAddr = publicListenAddr
 
 		// register myself once