add DigitalOcean provider

README.md

@@ -21,12 +21,15 @@ information.  There are two options:
 
 ## Supported providers
 
-Currently, this tool supports three cloud providers:
+Currently, this tool supports four cloud providers:
 
   * `aws`: Amazon Web Services
   * `azure`: Microsoft Azure Cloud
+  * `do`: Digital Ocean
   * `gcp`: Google Cloud Platform
 
+Not all providers support all network details.
+
 I am happy to accept pull requests to implement more providers.
 
 ## Supported Fields

discover/digitalocean.go

@@ -0,0 +1,37 @@
+package discover
+
+// TODO: decide out how, when, and if to return the Floating IP (URLs noted below)
+
+import (
+	"net"
+)
+
+const (
+	doPrivateIPv4URL               = "http://169.254.169.254/metadata/v1/interfaces/private/0/ipv4/address"
+	doPublicIPv4URL                = "http://169.254.169.254/metadata/v1/interfaces/public/0/ipv4/address"
+	doFloatingPublicIPv4EnabledURL = "http://169.254.169.254/metadata/v1/floating_ip/ipv4/active"
+	doFloatingPublicIPv4URL        = "http://169.254.169.254/metadata/v1/interfaces/public/0/anchor_ipv4/address"
+	doPublicIPv6URL                = "http://169.254.169.254/metadata/v1/interfaces/public/0/ipv6/address"
+)
+
+// NewDigitalOceanDiscoverer returns a new Digital Ocean network discoverer
+func NewDigitalOceanDiscoverer() Discoverer {
+	return NewDiscoverer(
+		PublicIPv4DiscovererOption(doPublicIPv4),
+		PublicIPv6DiscovererOption(doPublicIPv6),
+	)
+
+}
+
+// FIXME:  this URL never seems to be populated
+func doPrivateIPv4() (net.IP, error) {
+	return StandardIPFromHTTP(doPrivateIPv4URL, nil)
+}
+
+func doPublicIPv4() (net.IP, error) {
+	return StandardIPFromHTTP(doPublicIPv4URL, nil)
+}
+
+func doPublicIPv6() (net.IP, error) {
+	return StandardIPFromHTTP(doPublicIPv6URL, nil)
+}

discover/util.go

@@ -17,7 +17,7 @@ func ParseIPv4FromBody(in io.Reader) (net.IP, error) {
 		return nil, fmt.Errorf("failed to read response: %v", err)
 	}
 
-	if len(data) < 8 || len(data) > 18 {
+	if len(data) < 8 || len(data) > 42 {
 		return nil, fmt.Errorf("invalid response: %s", string(data))
 	}
 

main.go

@@ -18,7 +18,7 @@ var (
 
 func init() {
 	flag.BoolVar(&debug, "debug", false, `debug mode`)
-	flag.StringVar(&provider, "provider", "", `provider type.  Options are: "aws", "azure", "gcp"`)
+	flag.StringVar(&provider, "provider", "", `provider type.  Options are: "aws", "azure", "do", gcp"`)
 	flag.StringVar(&retField, "field", "", `return only a single field.  Options are: "hostname", "publicv4", publicv6", "privatev4"`)
 }
 
@@ -50,6 +50,8 @@ func main() {
 		discoverer = discover.NewAWSDiscoverer()
 	case "azure":
 		discoverer = discover.NewAzureDiscoverer()
+	case "do":
+		discoverer = discover.NewDigitalOceanDiscoverer()
 	case "gcp":
 		discoverer = discover.NewGCPDiscoverer()
 	default: