[OpenStack] Metadata service support

This commit adds support for retrieving instance metadata on OpenStack
public clouds.

Signed-off-by: Nick Jones <nick@dischord.org>

pkg/metadata/main.go

@@ -19,6 +19,10 @@ const (
 
 	// SSH is the path where sshd configuration from the provider is stored
 	SSH = "ssh"
+
+	// Standard AWS-compatible Metadata URLs
+	userDataURL = "http://169.254.169.254/latest/user-data"
+	metaDataURL = "http://169.254.169.254/latest/meta-data"
 )
 
 // Provider is a generic interface for metadata/userdata providers.
@@ -41,7 +45,7 @@ var netProviders []Provider
 var cdromProviders []Provider
 
 func main() {
-	providers := []string{"aws", "gcp", "vultr", "packet", "cdrom"}
+	providers := []string{"aws", "gcp", "openstack", "vultr", "packet", "cdrom"}
 	if len(os.Args) > 1 {
 		providers = os.Args[1:]
 	}
@@ -51,6 +55,8 @@ func main() {
 			netProviders = append(netProviders, NewAWS())
 		case "gcp":
 			netProviders = append(netProviders, NewGCP())
+		case "openstack":
+			netProviders = append(netProviders, NewOpenstack())
 		case "packet":
 			netProviders = append(netProviders, NewPacket())
 		case "vultr":

pkg/metadata/provider_aws.go

@@ -10,11 +10,6 @@ import (
 	"time"
 )
 
-const (
-	userDataURL = "http://169.254.169.254/latest/user-data"
-	metaDataURL = "http://169.254.169.254/latest/meta-data/"
-)
-
 // ProviderAWS is the type implementing the Provider interface for AWS
 type ProviderAWS struct {
 }

pkg/metadata/provider_openstack.go

@@ -0,0 +1,134 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"path"
+	"time"
+)
+
+// ProviderOpenstack is the type implementing the Provider interface for OpenStack
+type ProviderOpenstack struct {
+}
+
+// NewOpenstack returns a new ProviderOpenstack
+func NewOpenstack() *ProviderOpenstack {
+	return &ProviderOpenstack{}
+}
+
+func (p *ProviderOpenstack) String() string {
+	return "openstack"
+}
+
+// Probe checks if we are running on OpenStack
+func (p *ProviderOpenstack) Probe() bool {
+	// Getting the hostname should always work...
+	_, err := openstackGet(metaDataURL + "hostname")
+	return (err == nil)
+}
+
+// Extract gets both the OpenStack specific and generic userdata
+func (p *ProviderOpenstack) Extract() ([]byte, error) {
+	// Get host name. This must not fail
+	hostname, err := openstackGet(metaDataURL + "hostname")
+	if err != nil {
+		return nil, err
+	}
+	err = ioutil.WriteFile(path.Join(ConfigPath, Hostname), hostname, 0644)
+	if err != nil {
+		return nil, fmt.Errorf("OpenStack: Failed to write hostname: %s", err)
+	}
+
+	// public ipv4
+	openstackMetaGet("public-ipv4", "public_ipv4", 0644)
+
+	// private ipv4
+	openstackMetaGet("local-ipv4", "local_ipv4", 0644)
+
+	// availability zone
+	openstackMetaGet("placement/availability-zone", "availability_zone", 0644)
+
+	// instance type
+	openstackMetaGet("instance-type", "instance_type", 0644)
+
+	// instance-id
+	openstackMetaGet("instance-id", "instance_id", 0644)
+
+	// local-hostname
+	openstackMetaGet("local-hostname", "local_hostname", 0644)
+
+	// ssh
+	if err := p.handleSSH(); err != nil {
+		log.Printf("OpenStack: Failed to get ssh data: %s", err)
+	}
+
+	// Generic userdata
+	userData, err := openstackGet(userDataURL)
+	if err != nil {
+		log.Printf("OpenStack: Failed to get user-data: %s", err)
+		// This is not an error
+		return nil, nil
+	}
+	return userData, nil
+}
+
+// lookup a value (lookupName) in OpenStack's metaservice and store in given fileName
+func openstackMetaGet(lookupName string, fileName string, fileMode os.FileMode) {
+	if lookupValue, err := openstackGet(metaDataURL + 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("OpenStack: Failed to write %s:%s %s", fileName, lookupValue, err)
+		}
+	} else {
+		// we did not get a value back from the metadata server
+		log.Printf("OpenStack: Failed to get %s: %s", lookupName, err)
+	}
+}
+
+// openstackGet requests and extracts the requested URL
+func openstackGet(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("OpenStack: http.NewRequest failed: %s", err)
+	}
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("OpenStack: Could not contact metadata service: %s", err)
+	}
+	if resp.StatusCode != 200 {
+		return nil, fmt.Errorf("OpenStack: Status not ok: %d", resp.StatusCode)
+	}
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("OpenStack: Failed to read http response: %s", err)
+	}
+	return body, nil
+}
+
+// SSH keys:
+func (p *ProviderOpenstack) handleSSH() error {
+	sshKeys, err := openstackGet(metaDataURL + "public-keys/0/openssh-key")
+	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
+}