Fixes #366 (#367)

- Add `--inmemory-zone flag`
- Implement `InMemoryZoneInit` function to setup initial zones for
  inmemory provider
- Make "" the default zone for the inmemory provider instead of
  nil/none when no initial zones are specified
- Update config/flag parsing tests to accept new flag

main.go

@@ -117,7 +117,7 @@ func main() {
 			},
 		)
 	case "inmemory":
-		p, err = provider.NewInMemoryProvider(provider.InMemoryWithDomain(domainFilter), provider.InMemoryWithLogging()), nil
+		p, err = provider.NewInMemoryProvider(provider.InMemoryInitZones(cfg.InMemoryZones), provider.InMemoryWithDomain(domainFilter), provider.InMemoryWithLogging()), nil
 	default:
 		log.Fatalf("unknown dns provider: %s", cfg.Provider)
 	}

pkg/apis/externaldns/types.go

@@ -50,6 +50,7 @@ type Config struct {
 	InfobloxWapiPassword string
 	InfobloxWapiVersion  string
 	InfobloxSSLVerify    bool
+	InMemoryZones        []string
 	Policy               string
 	Registry             string
 	TXTOwnerID           string
@@ -83,6 +84,7 @@ var defaultConfig = &Config{
 	InfobloxWapiPassword: "",
 	InfobloxWapiVersion:  "2.3.1",
 	InfobloxSSLVerify:    true,
+	InMemoryZones:        []string{},
 	Policy:               "sync",
 	Registry:             "txt",
 	TXTOwnerID:           "default",
@@ -140,6 +142,7 @@ func (cfg *Config) ParseFlags(args []string) error {
 	app.Flag("infoblox-wapi-password", "When using the Infoblox provider, specify the WAPI password (required when --provider=infoblox)").Default(defaultConfig.InfobloxWapiPassword).StringVar(&cfg.InfobloxWapiPassword)
 	app.Flag("infoblox-wapi-version", "When using the Infoblox provider, specify the WAPI version (default: 2.3.1)").Default(defaultConfig.InfobloxWapiVersion).StringVar(&cfg.InfobloxWapiVersion)
 	app.Flag("infoblox-ssl-verify", "When using the Infoblox provider, specify whether to verify the SSL certificate (default: true)").Default(strconv.FormatBool(defaultConfig.InfobloxSSLVerify)).BoolVar(&cfg.InfobloxSSLVerify)
+	app.Flag("inmemory-zone", "Provide a list of pre-configured zones for the inmemory provider; specify multiple times for multiple zones (optional)").Default("").StringsVar(&cfg.InMemoryZones)
 
 	// Flags related to policies
 	app.Flag("policy", "Modify how DNS records are sychronized between sources and providers (default: sync, options: sync, upsert-only)").Default(defaultConfig.Policy).EnumVar(&cfg.Policy, "sync", "upsert-only")

pkg/apis/externaldns/types_test.go

@@ -47,6 +47,7 @@ var (
 		InfobloxWapiPassword: "",
 		InfobloxWapiVersion:  "2.3.1",
 		InfobloxSSLVerify:    true,
+		InMemoryZones:        []string{""},
 		Policy:               "sync",
 		Registry:             "txt",
 		TXTOwnerID:           "default",
@@ -79,6 +80,7 @@ var (
 		InfobloxWapiPassword: "infoblox",
 		InfobloxWapiVersion:  "2.6.1",
 		InfobloxSSLVerify:    false,
+		InMemoryZones:        []string{"example.org", "company.com"},
 		Policy:               "upsert-only",
 		Registry:             "noop",
 		TXTOwnerID:           "owner-1",
@@ -128,6 +130,8 @@ func TestParseFlags(t *testing.T) {
 				"--infoblox-wapi-username=infoblox",
 				"--infoblox-wapi-password=infoblox",
 				"--infoblox-wapi-version=2.6.1",
+				"--inmemory-zone=example.org",
+				"--inmemory-zone=company.com",
 				"--no-infoblox-ssl-verify",
 				"--domain-filter=example.org",
 				"--domain-filter=company.com",
@@ -167,6 +171,7 @@ func TestParseFlags(t *testing.T) {
 				"EXTERNAL_DNS_INFOBLOX_WAPI_PASSWORD": "infoblox",
 				"EXTERNAL_DNS_INFOBLOX_WAPI_VERSION":  "2.6.1",
 				"EXTERNAL_DNS_INFOBLOX_SSL_VERIFY":    "0",
+				"EXTERNAL_DNS_INMEMORY_ZONE":          "example.org\ncompany.com",
 				"EXTERNAL_DNS_DOMAIN_FILTER":          "example.org\ncompany.com",
 				"EXTERNAL_DNS_AWS_ZONE_TYPE":          "private",
 				"EXTERNAL_DNS_POLICY":                 "upsert-only",

provider/inmemory.go

@@ -79,6 +79,17 @@ func InMemoryWithDomain(domainFilter DomainFilter) InMemoryOption {
 	}
 }
 
+// InMemoryInitZones pre-seeds the InMemoryProvider with given zones
+func InMemoryInitZones(zones []string) InMemoryOption {
+	return func(p *InMemoryProvider) {
+		for _, z := range zones {
+			if err := p.CreateZone(z); err != nil {
+				log.Warnf("Unable to initialize zones for inmemory provider")
+			}
+		}
+	}
+}
+
 // NewInMemoryProvider returns InMemoryProvider DNS provider interface implementation
 func NewInMemoryProvider(opts ...InMemoryOption) *InMemoryProvider {
 	im := &InMemoryProvider{