metadata: add support for digitalocean

This adds support for fetching metadata and user data from the
DigitalOcean metadata service.

https://www.digitalocean.com/docs/droplets/resources/metadata/

Signed-off-by: salman aljammaz <s@aljmz.com>

pkg/metadata/main.go

@@ -78,7 +78,7 @@ func main() {
 		log.SetLevel(log.DebugLevel)
 	}
 
-	providers := []string{"aws", "gcp", "hetzner", "openstack", "scaleway", "vultr", "packet", "cdrom"}
+	providers := []string{"aws", "gcp", "hetzner", "openstack", "scaleway", "vultr", "digitalocean", "packet", "cdrom"}
 	args := flag.Args()
 	if len(args) > 0 {
 		providers = args
@@ -99,6 +99,8 @@ func main() {
 			netProviders = append(netProviders, NewScaleway())
 		case p == "vultr":
 			netProviders = append(netProviders, NewVultr())
+		case p == "digitalocean":
+			netProviders = append(netProviders, NewDigitalOcean())
 		case p == "cdrom":
 			cdromProviders = ListCDROMs()
 		case strings.HasPrefix(p, "file="):

pkg/metadata/provider_digitalocean.go

@@ -0,0 +1,132 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"path"
+	"time"
+)
+
+const (
+	digitalOceanMetaDataURL = "http://169.254.169.254/metadata/v1/"
+)
+
+// ProviderDigitalOcean is the type implementing the Provider interface for DigitalOcean
+type ProviderDigitalOcean struct {
+}
+
+// NewDigitalOcean returns a new ProviderDigitalOcean
+func NewDigitalOcean() *ProviderDigitalOcean {
+	return &ProviderDigitalOcean{}
+}
+
+func (p *ProviderDigitalOcean) String() string {
+	return "DigitalOcean"
+}
+
+// Probe checks if we are running on DigitalOcean
+func (p *ProviderDigitalOcean) Probe() bool {
+	// Getting the index should always work...
+	_, err := digitalOceanGet(digitalOceanMetaDataURL)
+	return (err == nil)
+}
+
+// Extract gets both the DigitalOcean specific and generic userdata
+func (p *ProviderDigitalOcean) Extract() ([]byte, error) {
+	// Get host name. This must not fail
+	hostname, err := digitalOceanGet(digitalOceanMetaDataURL + "hostname")
+	if err != nil {
+		return nil, err
+	}
+	err = ioutil.WriteFile(path.Join(ConfigPath, Hostname), hostname, 0644)
+	if err != nil {
+		return nil, fmt.Errorf("DigitalOcean: Failed to write hostname: %s", err)
+	}
+
+	// public ipv4
+	digitalOceanMetaGet("interfaces/public/0/ipv4/address", "public_ipv4", 0644)
+
+	// private ipv4
+	digitalOceanMetaGet("interfaces/private/0/ipv4/address", "private_ipv4", 0644)
+
+	// region
+	digitalOceanMetaGet("region", "region", 0644)
+
+	// droplet id
+	digitalOceanMetaGet("id", "id", 0644)
+
+	// ssh
+	if err := p.handleSSH(); err != nil {
+		log.Printf("DigitalOcean: Failed to get ssh data: %s", err)
+	}
+
+	// Generic userdata
+	userData, err := digitalOceanGet(digitalOceanMetaDataURL + "user-data")
+	if err != nil {
+		log.Printf("DigitalOcean: Failed to get user-data: %s", err)
+		// This is not an error
+		return nil, nil
+	}
+	return userData, nil
+}
+
+// lookup a value (lookupName) in DigitalOcean metaservice and store in given fileName
+func digitalOceanMetaGet(lookupName string, fileName string, fileMode os.FileMode) {
+	if lookupValue, err := digitalOceanGet(digitalOceanMetaDataURL + lookupName); err == nil {
+		// we got a value from the metadata server, now save to filesystem
+		err = ioutil.WriteFile(path.Join(ConfigPath, fileName), lookupValue, fileMode)
+		if err != nil {
+			// we couldn't save the file for some reason
+			log.Printf("DigitalOcean: Failed to write %s:%s %s", fileName, lookupValue, err)
+		}
+	} else {
+		// we did not get a value back from the metadata server
+		log.Printf("DigitalOcean: Failed to get %s: %s", lookupName, err)
+	}
+}
+
+// digitalOceanGet requests and extracts the requested URL
+func digitalOceanGet(url string) ([]byte, error) {
+	var client = &http.Client{
+		Timeout: time.Second * 2,
+	}
+
+	req, err := http.NewRequest("", url, nil)
+	if err != nil {
+		return nil, fmt.Errorf("DigitalOcean: http.NewRequest failed: %s", err)
+	}
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("DigitalOcean: Could not contact metadata service: %s", err)
+	}
+	if resp.StatusCode != 200 {
+		return nil, fmt.Errorf("DigitalOcean: Status not ok: %d", resp.StatusCode)
+	}
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("DigitalOcean: Failed to read http response: %s", err)
+	}
+	return body, nil
+}
+
+// SSH keys:
+func (p *ProviderDigitalOcean) handleSSH() error {
+	sshKeys, err := digitalOceanGet(digitalOceanMetaDataURL + "public-keys")
+	if err != nil {
+		return fmt.Errorf("Failed to get sshKeys: %s", err)
+	}
+
+	if err := os.Mkdir(path.Join(ConfigPath, SSH), 0755); err != nil {
+		return fmt.Errorf("Failed to create %s: %s", SSH, err)
+	}
+
+	err = ioutil.WriteFile(path.Join(ConfigPath, SSH, "authorized_keys"), sshKeys, 0600)
+	if err != nil {
+		return fmt.Errorf("Failed to write ssh keys: %s", err)
+	}
+	return nil
+}