Add support for Azure DNS

Closes #7

context.go

@@ -74,6 +74,11 @@ func (c *Context) InitContext() {
 
 	providerOpts := letsencrypt.ProviderOpts{
 		Provider:             letsencrypt.Provider(providerParam),
+		AzureClientId:        getEnvOption("AZURE_CLIENT_ID", false),
+		AzureClientSecret:    getEnvOption("AZURE_CLIENT_SECRET", false),
+		AzureSubscriptionId:  getEnvOption("AZURE_SUBSCRIPTION_ID", false),
+		AzureTenantId:        getEnvOption("AZURE_TENANT_ID", false),
+		AzureResourceGroup:   getEnvOption("AZURE_RESOURCE_GROUP", false),
 		CloudflareEmail:      getEnvOption("CLOUDFLARE_EMAIL", false),
 		CloudflareKey:        getEnvOption("CLOUDFLARE_KEY", false),
 		DoAccessToken:        getEnvOption("DO_ACCESS_TOKEN", false),

letsencrypt/providers.go

@@ -5,6 +5,7 @@ import (
 	"os"
 
 	lego "github.com/xenolf/lego/acme"
+	"github.com/xenolf/lego/providers/dns/azure"
 	"github.com/xenolf/lego/providers/dns/cloudflare"
 	"github.com/xenolf/lego/providers/dns/digitalocean"
 	"github.com/xenolf/lego/providers/dns/dnsimple"
@@ -20,6 +21,13 @@ import (
 type ProviderOpts struct {
 	Provider Provider
 
+	// Azure credentials
+	AzureClientId       string
+	AzureClientSecret   string
+	AzureSubscriptionId string
+	AzureTenantId       string
+	AzureResourceGroup  string
+
 	// CloudFlare credentials
 	CloudflareEmail string
 	CloudflareKey   string
@@ -55,6 +63,7 @@ type ProviderOpts struct {
 type Provider string
 
 const (
+	AZURE        = Provider("Azure")
 	CLOUDFLARE   = Provider("CloudFlare")
 	DIGITALOCEAN = Provider("DigitalOcean")
 	ROUTE53      = Provider("Route53")
@@ -72,6 +81,7 @@ type ProviderFactory struct {
 }
 
 var providerFactory = map[Provider]ProviderFactory{
+	AZURE:        ProviderFactory{makeAzureProvider, lego.DNS01},
 	CLOUDFLARE:   ProviderFactory{makeCloudflareProvider, lego.DNS01},
 	DIGITALOCEAN: ProviderFactory{makeDigitalOceanProvider, lego.DNS01},
 	ROUTE53:      ProviderFactory{makeRoute53Provider, lego.DNS01},
@@ -231,3 +241,29 @@ func makeHTTPProvider(opts ProviderOpts) (lego.ChallengeProvider, error) {
 	provider := lego.NewHTTPProviderServer("", "")
 	return provider, nil
 }
+
+// returns a preconfigured Azure lego.ChallengeProvider
+func makeAzureProvider(opts ProviderOpts) (lego.ChallengeProvider, error) {
+	if len(opts.AzureClientId) == 0 {
+		return nil, fmt.Errorf("Azure Client ID is not set")
+	}
+	if len(opts.AzureClientSecret) == 0 {
+		return nil, fmt.Errorf("Azure Client Secret is not set")
+	}
+	if len(opts.AzureSubscriptionId) == 0 {
+		return nil, fmt.Errorf("Azure Subscription ID is not set")
+	}
+	if len(opts.AzureTenantId) == 0 {
+		return nil, fmt.Errorf("Azure Tenant ID is not set")
+	}
+	if len(opts.AzureResourceGroup) == 0 {
+		return nil, fmt.Errorf("Azure Resource Group is not set")
+	}
+
+	provider, err := azure.NewDNSProviderCredentials(opts.AzureClientId, opts.AzureClientSecret, opts.AzureSubscriptionId,
+		opts.AzureTenantId, opts.AzureResourceGroup)
+	if err != nil {
+		return nil, err
+	}
+	return provider, nil
+}