metadata: Refactor metadata service into ec2 metadata

Added more testing.

datasource/metadata/ec2/metadata.go

@@ -0,0 +1,141 @@
+package ec2
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"github.com/coreos/coreos-cloudinit/pkg"
+)
+
+const (
+	DefaultAddress = "http://169.254.169.254/"
+	apiVersion     = "2009-04-04"
+	userdataUrl    = apiVersion + "/user-data"
+	metadataUrl    = apiVersion + "/meta-data"
+)
+
+type metadataService struct {
+	root   string
+	client pkg.Getter
+}
+
+func NewDatasource(root string) *metadataService {
+	if !strings.HasSuffix(root, "/") {
+		root += "/"
+	}
+	return &metadataService{root, pkg.NewHttpClient()}
+}
+
+func (ms metadataService) IsAvailable() bool {
+	_, err := ms.client.Get(ms.root + apiVersion)
+	return (err == nil)
+}
+
+func (ms metadataService) AvailabilityChanges() bool {
+	return true
+}
+
+func (ms metadataService) ConfigRoot() string {
+	return ms.root
+}
+
+func (ms metadataService) FetchMetadata() ([]byte, error) {
+	attrs := make(map[string]interface{})
+	if keynames, err := fetchAttributes(ms.client, fmt.Sprintf("%s/public-keys", ms.metadataUrl())); err == nil {
+		keyIDs := make(map[string]string)
+		for _, keyname := range keynames {
+			tokens := strings.SplitN(keyname, "=", 2)
+			if len(tokens) != 2 {
+				return nil, fmt.Errorf("malformed public key: %q", keyname)
+			}
+			keyIDs[tokens[1]] = tokens[0]
+		}
+
+		keys := make(map[string]string)
+		for name, id := range keyIDs {
+			sshkey, err := fetchAttribute(ms.client, fmt.Sprintf("%s/public-keys/%s/openssh-key", ms.metadataUrl(), id))
+			if err != nil {
+				return nil, err
+			}
+			keys[name] = sshkey
+			fmt.Printf("Found SSH key for %q\n", name)
+		}
+		attrs["public_keys"] = keys
+	} else if _, ok := err.(pkg.ErrNotFound); !ok {
+		return nil, err
+	}
+
+	if hostname, err := fetchAttribute(ms.client, fmt.Sprintf("%s/hostname", ms.metadataUrl())); err == nil {
+		attrs["hostname"] = hostname
+	} else if _, ok := err.(pkg.ErrNotFound); !ok {
+		return nil, err
+	}
+
+	if localAddr, err := fetchAttribute(ms.client, fmt.Sprintf("%s/local-ipv4", ms.metadataUrl())); err == nil {
+		attrs["local-ipv4"] = localAddr
+	} else if _, ok := err.(pkg.ErrNotFound); !ok {
+		return nil, err
+	}
+
+	if publicAddr, err := fetchAttribute(ms.client, fmt.Sprintf("%s/public-ipv4", ms.metadataUrl())); err == nil {
+		attrs["public-ipv4"] = publicAddr
+	} else if _, ok := err.(pkg.ErrNotFound); !ok {
+		return nil, err
+	}
+
+	if content_path, err := fetchAttribute(ms.client, fmt.Sprintf("%s/network_config/content_path", ms.metadataUrl())); err == nil {
+		attrs["network_config"] = map[string]string{
+			"content_path": content_path,
+		}
+	} else if _, ok := err.(pkg.ErrNotFound); !ok {
+		return nil, err
+	}
+
+	return json.Marshal(attrs)
+}
+
+func (ms metadataService) FetchUserdata() ([]byte, error) {
+	if data, err := ms.client.GetRetry(ms.userdataUrl()); err == nil {
+		return data, err
+	} else if _, ok := err.(pkg.ErrNotFound); ok {
+		return []byte{}, nil
+	} else {
+		return data, err
+	}
+}
+
+func (ms metadataService) Type() string {
+	return "ec2-metadata-service"
+}
+
+func (ms metadataService) metadataUrl() string {
+	return (ms.root + metadataUrl)
+}
+
+func (ms metadataService) userdataUrl() string {
+	return (ms.root + userdataUrl)
+}
+
+func fetchAttributes(client pkg.Getter, url string) ([]string, error) {
+	resp, err := client.GetRetry(url)
+	if err != nil {
+		return nil, err
+	}
+	scanner := bufio.NewScanner(bytes.NewBuffer(resp))
+	data := make([]string, 0)
+	for scanner.Scan() {
+		data = append(data, scanner.Text())
+	}
+	return data, scanner.Err()
+}
+
+func fetchAttribute(client pkg.Getter, url string) (string, error) {
+	if attrs, err := fetchAttributes(client, url); err == nil && len(attrs) > 0 {
+		return attrs[0], nil
+	} else {
+		return "", err
+	}
+}