Request to add DNS server implementation for sidecar

glide.yaml

@@ -63,3 +63,6 @@ import:
 
 - package: github.com/onsi/gomega
   version: 0fe204460da2c8fa1babcaac196e694de8f1aaa1
+
+- package: github.com/miekg/dns
+  version: db96a2b759cdef4f11a34506a42eb8d1290c598e

sidecar/config/config.go

@@ -72,6 +72,12 @@ type Controller struct {
 	Poll  time.Duration `yaml:"poll"`
 }
 
+// Dnsconfig - DNS server configuration
+type Dnsconfig struct {
+	Port   int    `yaml:"port"`
+	Domain string `yaml:"domain"`
+}
+
 // Health check types.
 const (
 	HTTPHealthCheck    = "http"
@@ -95,12 +101,14 @@ type HealthCheck struct {
 type Config struct {
 	Register bool `yaml:"register"`
 	Proxy    bool `yaml:"proxy"`
+	DNS      bool `yaml:"dns"`
 
 	Service  Service  `yaml:"service"`
 	Endpoint Endpoint `yaml:"endpoint"`
 
 	Registry   Registry   `yaml:"registry"`
 	Controller Controller `yaml:"controller"`
+	Dnsconfig  Dnsconfig  `yaml:"dnsconfig"`
 
 	HealthChecks []HealthCheck `yaml:"healthchecks"`
 
@@ -191,6 +199,7 @@ func (c *Config) loadFromContext(context *cli.Context) error {
 
 	loadFromContextIfSet(&c.Register, registerFlag)
 	loadFromContextIfSet(&c.Proxy, proxyFlag)
+	loadFromContextIfSet(&c.DNS, dnsFlag)
 	loadFromContextIfSet(&c.Endpoint.Host, endpointHostFlag)
 	loadFromContextIfSet(&c.Endpoint.Port, endpointPortFlag)
 	loadFromContextIfSet(&c.Endpoint.Type, endpointTypeFlag)
@@ -200,6 +209,8 @@ func (c *Config) loadFromContext(context *cli.Context) error {
 	loadFromContextIfSet(&c.Controller.URL, controllerURLFlag)
 	loadFromContextIfSet(&c.Controller.Token, controllerTokenFlag)
 	loadFromContextIfSet(&c.Controller.Poll, controllerPollFlag)
+	loadFromContextIfSet(&c.Dnsconfig.Port, dnsConfigPortFlag)
+	loadFromContextIfSet(&c.Dnsconfig.Domain, dnsConfigDomainFlag)
 	loadFromContextIfSet(&c.LogLevel, logLevelFlag)
 	loadFromContextIfSet(&c.Debug, debugFlag)
 
@@ -308,6 +319,13 @@ func (c *Config) Validate() error {
 
 	}
 
+	if c.DNS {
+		validators = append(validators,
+			IsInRange("Dns Port", c.Dnsconfig.Port, 1, 65535),
+			IsValidDomain("Dns Domain", c.Dnsconfig.Domain),
+		)
+	}
+
 	return Validate(validators)
 }
 

sidecar/config/config_test.go

@@ -52,11 +52,13 @@ var _ = Describe("Config", func() {
 		It("uses default config values", func() {
 			Expect(c.Register).To(Equal(DefaultConfig.Register))
 			Expect(c.Proxy).To(Equal(DefaultConfig.Proxy))
+			Expect(c.DNS).To(Equal(DefaultConfig.DNS))
 			Expect(c.Service).To(Equal(DefaultConfig.Service))
 			Expect(c.Endpoint.Port).To(Equal(DefaultConfig.Endpoint.Port))
 			Expect(c.Endpoint.Type).To(Equal(DefaultConfig.Endpoint.Type))
 			Expect(c.Registry).To(Equal(DefaultConfig.Registry))
 			Expect(c.Controller).To(Equal(DefaultConfig.Controller))
+			Expect(c.Dnsconfig).To(Equal(DefaultConfig.Dnsconfig))
 			Expect(c.HealthChecks).To(Equal(DefaultConfig.HealthChecks))
 			Expect(c.LogLevel).To(Equal(DefaultConfig.LogLevel))
 			Expect(c.Commands).To(HaveLen(0))
@@ -85,6 +87,7 @@ var _ = Describe("Config", func() {
 			args := append(os.Args[:1], []string{
 				"--register=true",
 				"--proxy=true",
+				"--dns=true",
 				"--service=helloworld:v1,somethingelse",
 				"--endpoint_host=localhost",
 				"--endpoint_port=9080",
@@ -95,6 +98,8 @@ var _ = Describe("Config", func() {
 				"--controller_url=http://controller:8080",
 				"--controller_token=local",
 				"--controller_poll=5s",
+				"--dns_port=4056",
+				"--dns_domain=someServer",
 				"--healthchecks=http://localhost:8082/health1",
 				"--healthchecks=http://localhost:8082/health2",
 				"--log_level=debug",
@@ -107,6 +112,7 @@ var _ = Describe("Config", func() {
 		It("uses config values from command line flags", func() {
 			Expect(c.Register).To(Equal(true))
 			Expect(c.Proxy).To(Equal(true))
+			Expect(c.DNS).To(Equal(true))
 			Expect(c.Service.Name).To(Equal("helloworld"))
 			Expect(c.Service.Tags).To(Equal([]string{"v1", "somethingelse"}))
 			Expect(c.Endpoint.Host).To(Equal("localhost"))
@@ -118,6 +124,8 @@ var _ = Describe("Config", func() {
 			Expect(c.Controller.URL).To(Equal("http://controller:8080"))
 			Expect(c.Controller.Token).To(Equal("local"))
 			Expect(c.Controller.Poll).To(Equal(time.Duration(5) * time.Second))
+			Expect(c.Dnsconfig.Port).To(Equal(4056))
+			Expect(c.Dnsconfig.Domain).To(Equal("someServer"))
 			Expect(c.HealthChecks[0].Value).To(Equal("http://localhost:8082/health1"))
 			Expect(c.HealthChecks[1].Value).To(Equal("http://localhost:8082/health2"))
 			Expect(c.LogLevel).To(Equal("debug"))
@@ -142,6 +150,7 @@ var _ = Describe("Config", func() {
 
 			os.Setenv("A8_REGISTER", "true")
 			os.Setenv("A8_PROXY", "true")
+			os.Setenv("A8_DNS", "true")
 			os.Setenv("A8_SERVICE", "helloworld:v1,somethingelse")
 			os.Setenv("A8_ENDPOINT_HOST", "localhost")
 			os.Setenv("A8_ENDPOINT_PORT", "9080")
@@ -152,9 +161,10 @@ var _ = Describe("Config", func() {
 			os.Setenv("A8_CONTROLLER_URL", "http://controller:8080")
 			os.Setenv("A8_CONTROLLER_TOKEN", "local")
 			os.Setenv("A8_CONTROLLER_POLL", "5s")
+			os.Setenv("A8_DNS_PORT", "4056")
+			os.Setenv("A8_DNS_DOMAIN", "someServer")
 			os.Setenv("A8_HEALTHCHECKS", "http://localhost:8082/health1,http://localhost:8082/health2")
 			os.Setenv("A8_LOG_LEVEL", "debug")
-
 			args := append(os.Args[:1], []string{
 				"python", "productpage.py",
 			}...)
@@ -164,6 +174,7 @@ var _ = Describe("Config", func() {
 		AfterEach(func() {
 			os.Unsetenv("A8_REGISTER")
 			os.Unsetenv("A8_PROXY")
+			os.Unsetenv("A8_DNS")
 			os.Unsetenv("A8_SERVICE")
 			os.Unsetenv("A8_ENDPOINT_HOST")
 			os.Unsetenv("A8_ENDPOINT_PORT")
@@ -174,13 +185,16 @@ var _ = Describe("Config", func() {
 			os.Unsetenv("A8_CONTROLLER_URL")
 			os.Unsetenv("A8_CONTROLLER_TOKEN")
 			os.Unsetenv("A8_CONTROLLER_POLL")
+			os.Unsetenv("A8_DNS_PORT")
+			os.Unsetenv("A8_DNS_DOMAIN")
 			os.Unsetenv("A8_HEALTHCHECKS")
 			os.Unsetenv("A8_LOG_LEVEL")
 		})
 
 		It("uses config values from environment variables", func() {
 			Expect(c.Register).To(Equal(true))
 			Expect(c.Proxy).To(Equal(true))
+			Expect(c.DNS).To(Equal(true))
 			Expect(c.Service.Name).To(Equal("helloworld"))
 			Expect(c.Service.Tags).To(Equal([]string{"v1", "somethingelse"}))
 			Expect(c.Endpoint.Host).To(Equal("localhost"))
@@ -192,6 +206,8 @@ var _ = Describe("Config", func() {
 			Expect(c.Controller.URL).To(Equal("http://controller:8080"))
 			Expect(c.Controller.Token).To(Equal("local"))
 			Expect(c.Controller.Poll).To(Equal(time.Duration(5) * time.Second))
+			Expect(c.Dnsconfig.Port).To(Equal(4056))
+			Expect(c.Dnsconfig.Domain).To(Equal("someServer"))
 			Expect(c.HealthChecks[0].Value).To(Equal("http://localhost:8082/health1"))
 			Expect(c.HealthChecks[1].Value).To(Equal("http://localhost:8082/health2"))
 			Expect(c.LogLevel).To(Equal("debug"))
@@ -216,7 +232,7 @@ var _ = Describe("Config", func() {
 			configYaml := `
 register: true
 proxy: true
-
+dns: true
 service:
   name: helloworld
   tags:
@@ -238,6 +254,11 @@ controller:
   token: local
   poll:  5s
 
+
+dnsconfig:
+  port:   4056
+  domain: someServer
+
 healthchecks:
   - type: http
     value: http://localhost:8082/health1
@@ -280,6 +301,7 @@ log_level: debug
 		It("uses config values from configuration file", func() {
 			Expect(c.Register).To(Equal(true))
 			Expect(c.Proxy).To(Equal(true))
+			Expect(c.DNS).To(Equal(true))
 			Expect(c.Service.Name).To(Equal("helloworld"))
 			Expect(c.Service.Tags).To(Equal([]string{"v1", "somethingelse"}))
 			Expect(c.Endpoint.Host).To(Equal("localhost"))
@@ -290,6 +312,8 @@ log_level: debug
 			Expect(c.Registry.Poll).To(Equal(time.Duration(5) * time.Second))
 			Expect(c.Controller.URL).To(Equal("http://controller:8080"))
 			Expect(c.Controller.Token).To(Equal("local"))
+			Expect(c.Dnsconfig.Port).To(Equal(4056))
+			Expect(c.Dnsconfig.Domain).To(Equal("someServer"))
 			Expect(c.Controller.Poll).To(Equal(time.Duration(5) * time.Second))
 			Expect(c.HealthChecks[0].Type).To(Equal("http"))
 			Expect(c.HealthChecks[0].Value).To(Equal("http://localhost:8082/health1"))
@@ -324,8 +348,13 @@ log_level: debug
 					URL:   "http://controller",
 					Poll:  60 * time.Second,
 				},
+				Dnsconfig: Dnsconfig{
+					Port:   8053,
+					Domain: "amalgam8",
+				},
 				Proxy:    true,
 				Register: true,
+				DNS:      true,
 				Service: Service{
 					Name: "mock",
 				},

sidecar/config/default.go

@@ -20,6 +20,7 @@ import "time"
 var DefaultConfig = Config{
 	Register: false,
 	Proxy:    false,
+	DNS:      false,
 
 	Service: Service{
 		Name: "",
@@ -42,6 +43,11 @@ var DefaultConfig = Config{
 		Poll:  time.Duration(15 * time.Second),
 	},
 
+	Dnsconfig: Dnsconfig{
+		Port:   8053,
+		Domain: "amalgam8",
+	},
+
 	HealthChecks: nil,
 
 	LogLevel: "info",

sidecar/config/flags.go

@@ -37,6 +37,9 @@ const (
 	controllerPollFlag  = "controller_poll"
 	healthchecksFlag    = "healthchecks"
 	logLevelFlag        = "log_level"
+	dnsFlag             = "dns"
+	dnsConfigPortFlag   = "dns_port"
+	dnsConfigDomainFlag = "dns_domain"
 	debugFlag           = "debug"
 )
 
@@ -61,6 +64,11 @@ var Flags = []cli.Flag{
 		EnvVar: envVar(proxyFlag),
 		Usage:  "Enable automatic service discovery and load balancing across services using NGINX",
 	},
+	cli.BoolFlag{
+		Name:   dnsFlag,
+		EnvVar: envVar(dnsFlag),
+		Usage:  "Enable DNS server",
+	},
 	cli.StringFlag{
 		Name:   serviceFlag,
 		EnvVar: envVar(serviceFlag),
@@ -111,6 +119,17 @@ var Flags = []cli.Flag{
 		EnvVar: envVar(controllerPollFlag),
 		Usage:  "Interval for polling Controller",
 	},
+
+	cli.StringFlag{
+		Name:   dnsConfigPortFlag,
+		EnvVar: envVar(dnsConfigPortFlag),
+		Usage:  "DNS server port number",
+	},
+	cli.StringFlag{
+		Name:   dnsConfigDomainFlag,
+		EnvVar: envVar(dnsConfigDomainFlag),
+		Usage:  "DNS server authorization domain name",
+	},
 	cli.StringSliceFlag{
 		Name:   healthchecksFlag,
 		EnvVar: envVar(healthchecksFlag),

sidecar/config/validation.go

@@ -19,6 +19,8 @@ import (
 	"fmt"
 	"net/url"
 	"time"
+
+	"github.com/miekg/dns"
 )
 
 // Validate runs validation checks
@@ -96,3 +98,17 @@ func IsInRangeDuration(name string, value, min, max time.Duration) ValidatorFunc
 		return nil
 	}
 }
+
+// IsValidDomain ensures the domain name is valid domain and that it contains only one domain.
+func IsValidDomain(name, value string) ValidatorFunc {
+	return func() error {
+		numberOfDomains, isValidDomain := dns.IsDomainName(value)
+		if !isValidDomain {
+			return errors.New(name + " not a valid domain")
+		}
+		if numberOfDomains != 1 {
+			return errors.New(name + " needs to contain 1 domain")
+		}
+		return nil
+	}
+}