Merge pull request #3 from phamhongviet/feature/custom-domain-name

Feature/custom domain name

README.md

@@ -26,13 +26,16 @@ $ dig +short oregon.region.redis.service.serf
 192.168.10.12
 ```
 
-Or to query a server with hostname node7.examp.le:
+Or to query a pre-configured domain name `us-web.serf` with name `web-.*` and tag `dc=us-.*`:
 
 ```
-$ dig +short node7.examp.le.name.serf
-192.168.7.17
+$ dig +short us-web.serf
+192.168.6.17
+192.168.7.18
+192.168.8.29
+192.168.9.105
 ```
-_Note_: querying hostname is not implemented yet
+_Note_: please see [custom-domain-name.md](custom-domain-name.md "Custom Domain Name") for more information.
 
 
 ## Develop
@@ -120,9 +123,18 @@ SERF_AUTH='S3creTT0k3n' ./serf-dns
 ./serf-dns --serf-auth='S3creTT0k3n'
 ```
 
+* __custom__: path to custom domain name file        
+Default: empty        
+Use environment variable `CUSTOM` or parameter `--custom=`        
+For example, to load custom domain names from /etc/serf-dns/custom.json:       
+```
+CUSTOM='/etc/serf-dns/custom.json' ./serf-dns
+./serf-dns --custom='/etc/serf-dns/custom.json'
+```
+Please see [custom-domain-name.md](custom-domain-name.md "Custom Domain Name") for more information.
+
 ## TODO
 
-* Support hostname query
 * Support configuration with file
 * Clean and test functions in main.go
 * Proper logging

config.go

@@ -5,11 +5,15 @@ import (
 )
 
 var (
-	config               = configure.New()
-	configBind           = config.String("bind", ":5327", "Bind with IP address and port")
-	configDomainName     = config.String("domain-name", "serf.", "Domain name")
-	configSerfRPCAddress = config.String("serf", "127.0.0.1:7373", "Serf RPC Address")
-	configSerfRPCAuthKey = config.String("serf-auth", "", "Serf RPC auth key")
+	config                     = configure.New()
+	configBind                 = config.String("bind", ":5327", "Bind with IP address and port")
+	configDomainName           = config.String("domain-name", "serf.", "Domain name")
+	configSerfRPCAddress       = config.String("serf", "127.0.0.1:7373", "Serf RPC Address")
+	configSerfRPCAuthKey       = config.String("serf-auth", "", "Serf RPC auth key")
+	configCustomDomainNameFile = config.String("custom", "", "Custom domain name file path")
+
+	// SerfFilterTable is a global table of serf filters loaded at boot
+	SerfFilterTable serfFilterTable
 )
 
 func init() {
@@ -25,5 +29,6 @@ Options:
 --domain-name    Specify domain name (default: serf.)
 --serf           Serf RPC address (default: 127.0.0.1:7373)
 --serf-auth      Serf RPC authentication key (default: empty)
+--custom         Custom domain name file path (default: none)
 `
 }

custom-domain-name.json

@@ -0,0 +1,21 @@
+{
+    "my-custom-dn-1.serf": {
+        "name": "^web-[0-5][0-9]",
+        "status": "alive",
+        "tags": {
+            "role": "web"
+        }
+    },
+    "failed.web.serf": {
+        "name": "^web-.*",
+        "status": "failed",
+        "tags": {
+            "role": "web"
+        }
+    },
+    "us.dc.serf": {
+        "tags": {
+            "dc": "us-.*"
+        }
+    }
+}

custom-domain-name.md

@@ -0,0 +1,45 @@
+# Custom Domain Name
+
+## Problem
+Using serf-dns with domain name parsed into tags has some limitation:
+- cannot use together with name and status
+- cannot use regex
+- limited to 127 labels, or 63 tags
+- limited to 253 characters in full domain name
+
+## Solution
+Use custom pre-registered domain name with pre-configured serf filters
+
+For example: configure domain name `my-custom-dn-1.serf` with name `^web-[0-5][0-9]`, and tags `role=web`
+
+Use a JSON file to configure custom domain name, like this:
+
+```json
+{
+	"my-custom-dn-1.serf": {
+		"name": "^web-[0-5][0-9]",
+		"status": "alive",
+		"tags": {
+			"role": "web"
+		}
+	},
+	"failed.web.serf": {
+		"name": "^web-.*",
+		"status": "failed",
+		"tags": {
+			"role": "web",
+			"version": "201605[0-9][0-9].*"
+		}
+	},
+	"us.dc.serf": {
+		"tags": {
+			"dc": "us-.*"
+		}
+	}
+}
+```
+
+The JSON file above will register 3 domain names:        
+- my-custom-dn-1.serf: return hosts named range from web-00 to web-59, still alive and tagged role=web
+- failed.web.serf: return hosts whose name start with web-, already dead and tagged role=web and version start with 201605
+- us.dc.serf: return hosts in US whose tag dc start with us-. Normally, query to this domain name will return hosts with tag dc=us

custom.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"encoding/json"
+)
+
+type serfFilterTable map[string]serfFilter
+
+func checkCustomDomainNameExistence(domainName string, sftab serfFilterTable) bool {
+	_, ok := sftab[domainName]
+	return ok
+}
+
+func loadCustomDomainName(data []byte) serfFilterTable {
+	var sftab serfFilterTable
+
+	// TODO: handle error here
+	json.Unmarshal(data, &sftab)
+	return sftab
+}

custom_test.go

@@ -0,0 +1,77 @@
+package main
+
+import (
+	"io/ioutil"
+	"testing"
+)
+
+func TestCheckCustomDomainNameExistence(t *testing.T) {
+	SFTable := serfFilterTable{
+		"dead.digit.serf.": serfFilter{
+			Name:   "^[0-9].*",
+			Status: "failed",
+		},
+		"digit.name.serf.": serfFilter{
+			Name:   "^[0-9].*",
+			Status: "alive",
+		},
+		"dead.serf.": serfFilter{
+			Status: "failed",
+		},
+	}
+
+	for dn := range SFTable {
+		ok := checkCustomDomainNameExistence(dn, SFTable)
+		if !ok {
+			t.Errorf("Failed to find existing custom domain name %s", dn)
+		}
+	}
+
+	for _, dn := range []string{"not.exist.serf.", "no.good.nope.", "also.not.exists."} {
+		ok := checkCustomDomainNameExistence(dn, SFTable)
+		if ok {
+			t.Errorf("Failed: Custom domain name %s actually does not exist", dn)
+		}
+	}
+}
+
+func TestLoadCustomDomainName(t *testing.T) {
+	data, err := ioutil.ReadFile("custom-domain-name.json")
+	if err != nil {
+		t.Errorf("Error reading data from custom-domain-name.json: %s", err.Error())
+	}
+
+	expect := serfFilterTable{
+		"my-custom-dn-1.serf": serfFilter{
+			Name:   "^web-[0-5][0-9]",
+			Status: "alive",
+			Tags: map[string]string{
+				"role": "web",
+			},
+		},
+		"failed.web.serf": serfFilter{
+			Name:   "^web-.*",
+			Status: "failed",
+			Tags: map[string]string{
+				"role": "web",
+			},
+		},
+		"us.dc.serf": serfFilter{
+			Tags: map[string]string{
+				"dc": "us-.*",
+			},
+		},
+	}
+	result := loadCustomDomainName(data)
+
+	if len(expect) != len(result) {
+		t.Errorf("Failed to load custom domain name: result serf filter table is different from the expected one.")
+	}
+
+	for dn, sf := range expect {
+		resultSF := result[dn]
+		if sf.Compare(resultSF) != true {
+			t.Errorf("Failed to load custom domain name: result serf filter table is different from the expected one.")
+		}
+	}
+}

main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"io/ioutil"
 	"os"
 	"os/signal"
 	"syscall"
@@ -15,7 +16,7 @@ func handle(writer dns.ResponseWriter, request *dns.Msg, serfClient *serf_client
 	message.SetReply(request)
 
 	for _, question := range request.Question {
-		filter := parseDomainName(question.Name)
+		filter := parseDomainName(question.Name, SerfFilterTable)
 		hosts, err := getSerfMembers(serfClient, filter)
 		if err != nil {
 			fmt.Println(err.Error())
@@ -40,6 +41,15 @@ func serve(net string, address string) {
 func main() {
 	config.Parse()
 
+	if *configCustomDomainNameFile != "" {
+		customDNData, err := ioutil.ReadFile(*configCustomDomainNameFile)
+		if err != nil {
+			fmt.Println(err.Error())
+		} else {
+			SerfFilterTable = loadCustomDomainName(customDNData)
+		}
+	}
+
 	serfClient, err := connectSerfAgent(*configSerfRPCAddress, *configSerfRPCAuthKey)
 	defer closeSerfConnection(serfClient)
 	if err != nil {

parse.go

@@ -4,7 +4,15 @@ import (
 	"strings"
 )
 
-func parseDomainName(domainName string) serfFilter {
+func parseDomainName(domainName string, sftab serfFilterTable) serfFilter {
+	customDomainNameExist := checkCustomDomainNameExistence(domainName, sftab)
+	if customDomainNameExist {
+		return parseCustomDomainName(domainName, sftab)
+	}
+	return parseTagsDomainName(domainName)
+}
+
+func parseTagsDomainName(domainName string) serfFilter {
 	domainName = strings.TrimSuffix(domainName, *configDomainName)
 
 	tags := make(map[string]string)
@@ -33,3 +41,7 @@ func findTag(domainName string) (tagValue, tagName, remain string) {
 	res := strings.SplitN(domainName, ".", 3)
 	return res[0], res[1], res[2]
 }
+
+func parseCustomDomainName(domainName string, sftab serfFilterTable) serfFilter {
+	return sftab[domainName]
+}

parse_test.go

@@ -7,6 +7,46 @@ import (
 func TestParseDomainName(t *testing.T) {
 	config.Parse()
 
+	SFTable := serfFilterTable{
+		"dead.digit.serf.": serfFilter{
+			Name:   "^[0-9].*",
+			Status: "failed",
+		},
+		"digit.name.serf.": serfFilter{
+			Name:   "^[0-9].*",
+			Status: "alive",
+		},
+		"dead.serf.": serfFilter{
+			Status: "failed",
+		},
+	}
+
+	for dn, sf := range SFTable {
+		resultSF := parseDomainName(dn, SFTable)
+		ok := sf.Compare(resultSF)
+		if !ok {
+			t.Errorf("Failed to parse custom domain name %s", dn)
+		}
+	}
+
+	domainNameSample := "foo.srv.cali.dc.serf."
+	expect := serfFilter{
+		Tags: map[string]string{
+			"srv": "foo",
+			"dc":  "cali",
+		},
+		Status: "alive",
+	}
+	result := parseDomainName(domainNameSample, SFTable)
+	ok := expect.Compare(result)
+	if !ok {
+		t.Errorf("Failed to parse domain name %s", domainNameSample)
+	}
+}
+
+func TestParseTagsDomainName(t *testing.T) {
+	config.Parse()
+
 	domainNameSample := "foo.srv.cali.dc.serf."
 	expectedSerfFilter := serfFilter{
 		Tags: map[string]string{
@@ -15,7 +55,7 @@ func TestParseDomainName(t *testing.T) {
 		},
 		Status: "alive",
 	}
-	resultSerfFilter := parseDomainName(domainNameSample)
+	resultSerfFilter := parseTagsDomainName(domainNameSample)
 	ok := expectedSerfFilter.Compare(resultSerfFilter)
 	if !ok {
 		t.Errorf("Failed to parse domain name %s", domainNameSample)
@@ -41,3 +81,27 @@ func TestFindTag(t *testing.T) {
 		t.Errorf("Failed to find tag in domain name")
 	}
 }
+
+func TestParseCustomDomainName(t *testing.T) {
+	SFTable := serfFilterTable{
+		"dead.digit.serf.": serfFilter{
+			Name:   "^[0-9].*",
+			Status: "failed",
+		},
+		"digit.name.serf.": serfFilter{
+			Name:   "^[0-9].*",
+			Status: "alive",
+		},
+		"dead.serf.": serfFilter{
+			Status: "failed",
+		},
+	}
+
+	for dn, sf := range SFTable {
+		resultSF := parseCustomDomainName(dn, SFTable)
+		ok := sf.Compare(resultSF)
+		if !ok {
+			t.Errorf("Failed to parse custom domain name %s", dn)
+		}
+	}
+}