Support ALIAS records with Cloudflare (#89)

* simple facility for registering provider capabilities

* support for cloudflare. tests.

* js and docs

* docs

* generate

docs/_functions/domain/ALIAS.md

@@ -0,0 +1,25 @@
+---
+name: ALIAS
+parameters:
+  - name
+  - target
+  - modifiers...
+---
+
+ALIAS is a virtual record type that points a record at another record. It is analagous to a CNAME, but is usually resolved at request-time and served as an A record. Unlike CNAMEs, ALIAS records can be used at the zone apex (`@`)
+
+Different providers handle ALIAS records differently, and many do not support it at all. Attempting to use ALIAS records with a DNS provider type that does not support them will result in an error.
+
+The name should be the relative label for the domain.
+
+Target should be a string representing the target. If it is a single label we will assume it is a relative name on the current domain. If it contains *any* dots, it should be a fully qualified domain name, ending with a `.`.
+
+{% include startExample.html %}
+{% highlight js %}
+
+D("example.com", REGISTRAR, DnsProvider("CLOUDFLARE"),
+  ALIAS("@", "google.com."), // example.com -> google.com
+);
+
+{%endhighlight%}
+{% include endExample.html %}

docs/alias.md

@@ -0,0 +1,25 @@
+---
+layout: default
+---
+
+# ALIAS records
+
+ALIAS records are not widely standardized across DNS providers. Some (Route 53, DNSimple) have a native ALIAS record type. Others (Cloudflare) implement transparent CNAME flattening.
+
+DNSControl adds an ALIAS record type, and leaves it up to the provider implementation to handle it.
+
+A few notes:
+
+1. A provider must "opt-in" to supporting ALIAS records. When registering a provider, you specify which capabilities you support. Here is an example of how the 
+  cloudflare provider declares its support for aliases:
+
+```
+func init() {
+	providers.RegisterDomainServiceProviderType("CLOUDFLAREAPI", newCloudflare, providers.CanUseAlias)
+}
+```
+
+2. If you try to use ALIAS records, **all** dns providers for the domain must support ALIAS records. We do not want to serve inconsistent records across providers.
+3. CNAMEs at `@` are disallowed, but ALIAS is allowed. 
+4. Cloudflare does not have a native ALIAS type, but CNAMEs behave similarly. The Cloudflare provider "rewrites" ALIAS records to CNAME as it sees them. Other providers may not need this step.
+

docs/index.md

@@ -23,3 +23,4 @@ Dnscontrol is a platform for seamlessly managing your dns configuration across a
 
 - [Why CNAME/MX/NS targets require a trailing "dot"]({{site.github.url}}/why-the-dot)
 - [Writing Providers]({{site.github.url}}/writing-providers)
+- [ALIAS records in dnscontrol]({{site.github.url}}/alias)

integrationTest/integration_test.go

@@ -97,6 +97,10 @@ func runTests(t *testing.T, prv providers.DNSServiceProvider, domainName string,
 			break
 		}
 		t.Run(fmt.Sprintf("%d: %s", i, tst.Desc), func(t *testing.T) {
+			if tst.SkipUnless != 0 && !providers.ProviderHasCabability(*providerToRun, tst.SkipUnless) {
+				t.Log("Skipping because provider does not support test features")
+				return
+			}
 			skipVal := false
 			if knownFailures[i] {
 				t.Log("SKIPPING VALIDATION FOR KNOWN FAILURE CASE")
@@ -188,6 +192,7 @@ func TestDualProviders(t *testing.T) {
 type TestCase struct {
 	Desc       string
 	Records    []*rec
+	SkipUnless providers.Capability
 }
 
 type rec models.RecordConfig
@@ -200,6 +205,10 @@ func cname(name, target string) *rec {
 	return makeRec(name, target, "CNAME")
 }
 
+func alias(name, target string) *rec {
+	return makeRec(name, target, "ALIAS")
+}
+
 func ns(name, target string) *rec {
 	return makeRec(name, target, "NS")
 }
@@ -231,6 +240,11 @@ func tc(desc string, recs ...*rec) *TestCase {
 	}
 }
 
+func (tc *TestCase) IfHasCapability(c providers.Capability) *TestCase {
+	tc.SkipUnless = c
+	return tc
+}
+
 //ALWAYS ADD TO BOTTOM OF LIST. Order and indexes matter.
 var tests = []*TestCase{
 	// A
@@ -274,5 +288,12 @@ var tests = []*TestCase{
 	tc("Change to other name", mx("@", 5, "foo2.com."), mx("mail", 15, "foo3.com.")),
 	tc("Change Priority", mx("@", 7, "foo2.com."), mx("mail", 15, "foo3.com.")),
 
-	tc("IDN pre-punycoded", cname("xn--o-0gab", "xn--o-0gab.xn--o-0gab.")),
+	//ALIAS
+	tc("EMPTY"),
+	tc("ALIAS at root", alias("@", "foo.com.")).IfHasCapability(providers.CanUseAlias),
+	tc("change it", alias("@", "foo2.com.")).IfHasCapability(providers.CanUseAlias),
+	tc("ALIAS at subdomain", alias("test", "foo.com.")).IfHasCapability(providers.CanUseAlias),
+
+	//TODO: in validation, check that everything is given in unicode. This case hurts too much.
+	//tc("IDN pre-punycoded", cname("xn--o-0gab", "xn--o-0gab.xn--o-0gab.")),
 }

integrationTest/providers.json

@@ -1,7 +1,17 @@
 {
+    "ACTIVEDIRECTORY_PS": {
+        "knownFailures": "17,18,19,25,26,27,28,29,30",
+        "domain": "$AD_DOMAIN",
+        "ADServer": "$AD_SERVER"
+    },
     "BIND": {
         "domain": "example.com"
     },
+    "CLOUDFLAREAPI":{
+        "domain": "$CF_DOMAIN",
+        "apiuser": "$CF_USER",
+        "apikey": "$CF_KEY"
+    },
     "DNSIMPLE": {
         //16/17: no ns records managable. Not even for subdomains.
         "knownFailures": "17,18",
@@ -25,10 +35,5 @@
         "domain": "$R53_DOMAIN",
         "KeyId": "$R53_KEY_ID",
         "SecretKey": "$R53_KEY"
-    },
-    "ACTIVEDIRECTORY_PS":{
-        "knownFailures": "17,18,19,25,26,27,28,29,30",
-        "domain": "$AD_DOMAIN",
-        "ADServer": "$AD_SERVER"
     }
 }

integrationTest/zones/example.com.zone

@@ -1,4 +1,2 @@
 $TTL 300
-@                IN SOA   DEFAULT_NOT_SET. DEFAULT_NOT_SET. 2017032394 3600 600 604800 1440
-                 IN MX    7 foo2.com.
-mail             IN MX    15 foo3.com.
+@                IN SOA   DEFAULT_NOT_SET. DEFAULT_NOT_SET. 2017041717 3600 600 604800 1440

js/helpers.js

@@ -123,6 +123,15 @@ function AAAA(name, ip) {
     }
 }
 
+// ALIAS(name,target, recordModifiers...)
+function ALIAS(name, target) {
+    var mods = getModifiers(arguments,2)
+    return function(d) {
+        addRecord(d,"ALIAS",name,target,mods)
+    }
+}
+
+
 // CNAME(name,target, recordModifiers...)
 function CNAME(name, target) {
     var mods = getModifiers(arguments,2)

js/js_test.go

@@ -30,7 +30,7 @@ func TestParsedFiles(t *testing.T) {
 		if filepath.Ext(f.Name()) != ".js" || !unicode.IsNumber(rune(f.Name()[0])) {
 			continue
 		}
-		t.Log(f.Name(), "------")
+		t.Run(f.Name(), func(t *testing.T) {
 			content, err := ioutil.ReadFile(filepath.Join(testDir, f.Name()))
 			if err != nil {
 				t.Fatal(err)
@@ -39,7 +39,7 @@ func TestParsedFiles(t *testing.T) {
 			if err != nil {
 				t.Fatal(err)
 			}
-		actualJson, err := json.MarshalIndent(conf, "", "  ")
+			actualJSON, err := json.MarshalIndent(conf, "", "  ")
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -49,20 +49,21 @@ func TestParsedFiles(t *testing.T) {
 				t.Fatal(err)
 			}
 			conf = &models.DNSConfig{}
+			//unmarshal and remarshal to not require manual formatting
 			err = json.Unmarshal(expectedData, conf)
 			if err != nil {
 				t.Fatal(err)
 			}
-		expectedJson, err := json.MarshalIndent(conf, "", "  ")
+			expectedJSON, err := json.MarshalIndent(conf, "", "  ")
 			if err != nil {
 				t.Fatal(err)
 			}
-		if string(expectedJson) != string(actualJson) {
+			if string(expectedJSON) != string(actualJSON) {
 				t.Error("Expected and actual json don't match")
-			t.Log("Expected:", string(expectedJson))
-			t.Log("Actual:", string(actualJson))
-			t.FailNow()
+				t.Log("Expected:", string(expectedJSON))
+				t.Log("Actual:", string(actualJSON))
 			}
+		})
 	}
 }
 

js/parse_tests/010-alias.js

@@ -0,0 +1,3 @@
+D("foo.com","none",
+    ALIAS("@","foo.com.")
+);

js/parse_tests/010-alias.json

@@ -0,0 +1,19 @@
+{
+		  "registrars": [],
+		  "dns_providers": [],
+		  "domains": [
+		    {
+		      "name": "foo.com",
+		      "registrar": "none",
+		      "dnsProviders": {},
+		      "records": [
+		        {
+		          "type": "ALIAS",
+		          "name": "@",
+		          "target": "foo.com."
+		        }
+		      ],
+		      "keepunknown": false
+		    }
+		  ]
+		}

js/static.go

@@ -190,48 +190,48 @@ var _escData = map[string]*_escFile{
 
 	"/helpers.js": {
 		local:   "js/helpers.js",
-		size:    7563,
+		size:    7758,
 		modtime: 0,
 		compressed: `
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 `,
 	},
 

normalize/validate.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 
 	"github.com/StackExchange/dnscontrol/models"
+	"github.com/StackExchange/dnscontrol/providers"
 	"github.com/StackExchange/dnscontrol/transform"
 	"github.com/miekg/dns"
 	"github.com/miekg/dns/dnsutil"
@@ -52,6 +53,7 @@ func validateRecordTypes(rec *models.RecordConfig, domain string) error {
 		"MX":               true,
 		"TXT":              true,
 		"NS":               true,
+		"ALIAS":            false,
 	}
 
 	if _, ok := validTypes[rec.Type]; !ok {
@@ -112,6 +114,9 @@ func checkTargets(rec *models.RecordConfig, domain string) (errs []error) {
 		check(checkIPv6(target))
 	case "CNAME":
 		check(checkTarget(target))
+		if label == "@" {
+			check(fmt.Errorf("cannot create CNAME record for bare domain"))
+		}
 	case "MX":
 		check(checkTarget(target))
 	case "NS":
@@ -119,6 +124,8 @@ func checkTargets(rec *models.RecordConfig, domain string) (errs []error) {
 		if label == "@" {
 			check(fmt.Errorf("cannot create NS record for bare domain. Use NAMESERVER instead"))
 		}
+	case "ALIAS":
+		check(checkTarget(target))
 	case "TXT", "IMPORT_TRANSFORM":
 	default:
 		errs = append(errs, fmt.Errorf("Unimplemented record type (%v) domain=%v name=%v",
@@ -260,9 +267,20 @@ func NormalizeAndValidateConfig(config *models.DNSConfig) (errs []error) {
 			errs = append(errs, err)
 		}
 	}
+
+	//Check that CNAMES don't have to co-exist with any other records
 	for _, d := range config.Domains {
 		errs = append(errs, checkCNAMEs(d)...)
 	}
+
+	//Check that if any aliases are used in a domain, every provider for that domain supports them
+	for _, d := range config.Domains {
+		err := checkALIASes(d, config.DNSProviders)
+		if err != nil {
+			errs = append(errs, nil)
+		}
+	}
+
 	return errs
 }
 
@@ -284,6 +302,30 @@ func checkCNAMEs(dc *models.DomainConfig) (errs []error) {
 	return
 }
 
+func checkALIASes(dc *models.DomainConfig, pList []*models.DNSProviderConfig) error {
+	hasAlias := false
+	for _, r := range dc.Records {
+		if r.Type == "ALIAS" {
+			hasAlias = true
+			break
+		}
+	}
+	if !hasAlias {
+		return nil
+	}
+	for pName := range dc.DNSProviders {
+		for _, p := range pList {
+			if p.Name == pName {
+				if !providers.ProviderHasCabability(p.Type, providers.CanUseAlias) {
+					return fmt.Errorf("Domain %s uses ALIAS records, but DNS provider type %s does not support them", dc.Name, p.Type)
+				}
+				break
+			}
+		}
+	}
+	return nil
+}
+
 func applyRecordTransforms(domain *models.DomainConfig) error {
 	for _, rec := range domain.Records {
 		if rec.Type != "A" {

providers/cloudflare/cloudflareProvider.go

@@ -81,7 +81,6 @@ func (c *CloudflareApi) GetDomainCorrections(dc *models.DomainConfig) ([]*models
 	if err != nil {
 		return nil, err
 	}
-	//for _, rec := range records {
 	for i := len(records) - 1; i >= 0; i-- {
 		rec := records[i]
 		// Delete ignore labels
@@ -91,9 +90,11 @@ func (c *CloudflareApi) GetDomainCorrections(dc *models.DomainConfig) ([]*models
 		}
 	}
 	for _, rec := range dc.Records {
+		if rec.Type == "ALIAS" {
+			rec.Type = "CNAME"
+		}
 		if labelMatches(rec.Name, c.ignoredLabels) {
 			log.Fatalf("FATAL: dnsconfig contains label that matches ignored_labels: %#v is in %v)\n", rec.Name, c.ignoredLabels)
-			// Since we log.Fatalf, we don't need to be clean here.
 		}
 	}
 	checkNSModifications(dc)
@@ -166,9 +167,15 @@ func (c *CloudflareApi) preprocessConfig(dc *models.DomainConfig) error {
 	// A and CNAMEs: Validate. If null, set to default.
 	// else: Make sure it wasn't set.  Set to default.
 	for _, rec := range dc.Records {
+		if rec.Metadata == nil {
+			rec.Metadata = map[string]string{}
+		}
 		if rec.TTL == 0 || rec.TTL == 300 {
 			rec.TTL = 1
 		}
+		if rec.TTL != 1 && rec.TTL < 120 {
+			rec.TTL = 120
+		}
 		if rec.Type != "A" && rec.Type != "CNAME" && rec.Type != "AAAA" {
 			if rec.Metadata[metaProxy] != "" {
 				return fmt.Errorf("cloudflare_proxy set on %v record: %#v cloudflare_proxy=%#v", rec.Type, rec.Name, rec.Metadata[metaProxy])
@@ -243,7 +250,7 @@ func newCloudflare(m map[string]string, metadata json.RawMessage) (providers.DNS
 }
 
 func init() {
-	providers.RegisterDomainServiceProviderType("CLOUDFLAREAPI", newCloudflare)
+	providers.RegisterDomainServiceProviderType("CLOUDFLAREAPI", newCloudflare, providers.CanUseAlias)
 }
 
 // Used on the "existing" records.

providers/providers.go

@@ -34,6 +34,21 @@ var registrarTypes = map[string]RegistrarInitializer{}
 type DspInitializer func(map[string]string, json.RawMessage) (DNSServiceProvider, error)
 
 var dspTypes = map[string]DspInitializer{}
+var dspCapabilities = map[string]Capability{}
+
+//Capability is a bitmasked set of "features" that a provider supports. Only use constants from this package.
+type Capability uint32
+
+const (
+	// CanUseAlias indicates the provider support ALIAS records (or flattened CNAMES). Up to the provider to translate them to the appropriate record type.
+	CanUseAlias Capability = 1 << iota
+	// CanUsePTR indicates the provider can handle PTR records
+	CanUsePTR
+)
+
+func ProviderHasCabability(pType string, cap Capability) bool {
+	return dspCapabilities[pType]&cap != 0
+}
 
 //RegisterRegistrarType adds a registrar type to the registry by providing a suitable initialization function.
 func RegisterRegistrarType(name string, init RegistrarInitializer) {
@@ -44,11 +59,16 @@ func RegisterRegistrarType(name string, init RegistrarInitializer) {
 }
 
 //RegisterDomainServiceProviderType adds a dsp to the registry with the given initialization function.
-func RegisterDomainServiceProviderType(name string, init DspInitializer) {
+func RegisterDomainServiceProviderType(name string, init DspInitializer, caps ...Capability) {
 	if _, ok := dspTypes[name]; ok {
 		log.Fatalf("Cannot register registrar type %s multiple times", name)
 	}
+	var abilities Capability
+	for _, c := range caps {
+		abilities |= c
+	}
 	dspTypes[name] = init
+	dspCapabilities[name] = abilities
 }
 
 func createRegistrar(rType string, config map[string]string) (Registrar, error) {