Merge pull request #215 from Carevoyance/gce_fingerprint

Add GCE fingerprinting functionality

client/fingerprint/env_aws.go

@@ -62,12 +62,12 @@ var ec2InstanceSpeedMap = map[string]int{
 	"d2.8xlarge":  10000,
 }
 
-// EnvAWSFingerprint is used to fingerprint the CPU
+// EnvAWSFingerprint is used to fingerprint AWS metadata
 type EnvAWSFingerprint struct {
 	logger *log.Logger
 }
 
-// NewEnvAWSFingerprint is used to create a CPU fingerprint
+// NewEnvAWSFingerprint is used to create a fingerprint from AWS metadata
 func NewEnvAWSFingerprint(logger *log.Logger) Fingerprint {
 	f := &EnvAWSFingerprint{logger: logger}
 	return f

client/fingerprint/env_gce.go

@@ -0,0 +1,229 @@
+package fingerprint
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"net/url"
+	"os"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/hashicorp/nomad/client/config"
+	"github.com/hashicorp/nomad/nomad/structs"
+)
+
+// This is where the GCE metadata server normally resides. We hardcode the
+// "instance" path as well since it's the only one we access here.
+const DEFAULT_GCE_URL = "http://169.254.169.254/computeMetadata/v1/instance/"
+
+type GCEMetadataNetworkInterface struct {
+	AccessConfigs []struct {
+		ExternalIp string
+		Type       string
+	}
+	ForwardedIps []string
+	Ip           string
+	Network      string
+}
+
+type ReqError struct {
+	StatusCode int
+}
+
+func (e ReqError) Error() string {
+	return http.StatusText(e.StatusCode)
+}
+
+func lastToken(s string) string {
+	index := strings.LastIndex(s, "/")
+	return s[index+1:]
+}
+
+// EnvGCEFingerprint is used to fingerprint GCE metadata
+type EnvGCEFingerprint struct {
+	client      *http.Client
+	logger      *log.Logger
+	metadataURL string
+}
+
+// NewEnvGCEFingerprint is used to create a fingerprint from GCE metadata
+func NewEnvGCEFingerprint(logger *log.Logger) Fingerprint {
+	// Read the internal metadata URL from the environment, allowing test files to
+	// provide their own
+	metadataURL := os.Getenv("GCE_ENV_URL")
+	if metadataURL == "" {
+		metadataURL = DEFAULT_GCE_URL
+	}
+
+	// assume 2 seconds is enough time for inside GCE network
+	client := &http.Client{
+		Timeout: 2 * time.Second,
+	}
+
+	return &EnvGCEFingerprint{
+		client:      client,
+		logger:      logger,
+		metadataURL: metadataURL,
+	}
+}
+
+func (f *EnvGCEFingerprint) Get(attribute string, recursive bool) (string, error) {
+	reqUrl := f.metadataURL + attribute
+	if recursive {
+		reqUrl = reqUrl + "?recursive=true"
+	}
+
+	parsedUrl, err := url.Parse(reqUrl)
+	if err != nil {
+		return "", err
+	}
+
+	req := &http.Request{
+		Method: "GET",
+		URL:    parsedUrl,
+		Header: http.Header{
+			"Metadata-Flavor": []string{"Google"},
+		},
+	}
+
+	res, err := f.client.Do(req)
+	if err != nil {
+		return "", err
+	}
+
+	resp, err := ioutil.ReadAll(res.Body)
+	res.Body.Close()
+	if err != nil {
+		f.logger.Printf("[ERR]: fingerprint.env_gce: Error reading response body for GCE %s", attribute)
+		return "", err
+	}
+
+	if res.StatusCode >= 400 {
+		return "", ReqError{res.StatusCode}
+	}
+
+	return string(resp), nil
+}
+
+func checkError(err error, logger *log.Logger, desc string) error {
+	// If it's a URL error, assume we're not actually in an GCE environment.
+	// To the outer layers, this isn't an error so return nil.
+	if _, ok := err.(*url.Error); ok {
+		logger.Printf("[ERR] fingerprint.env_gce: Error querying GCE " + desc + ", skipping")
+		return nil
+	}
+	// Otherwise pass the error through.
+	return err
+}
+
+func (f *EnvGCEFingerprint) Fingerprint(cfg *config.Config, node *structs.Node) (bool, error) {
+	if !f.isGCE() {
+		return false, nil
+	}
+
+	if node.Links == nil {
+		node.Links = make(map[string]string)
+	}
+
+	keys := []string{
+		"hostname",
+		"id",
+		"cpu-platform",
+		"scheduling/automatic-restart",
+		"scheduling/on-host-maintenance",
+	}
+	for _, k := range keys {
+		value, err := f.Get(k, false)
+		if err != nil {
+			return false, checkError(err, f.logger, k)
+		}
+
+		// assume we want blank entries
+		key := strings.Replace(k, "/", ".", -1)
+		node.Attributes["platform.gce."+key] = strings.Trim(string(value), "\n")
+	}
+
+	// These keys need everything before the final slash removed to be usable.
+	keys = []string{
+		"machine-type",
+		"zone",
+	}
+	for _, k := range keys {
+		value, err := f.Get(k, false)
+		if err != nil {
+			return false, checkError(err, f.logger, k)
+		}
+
+		node.Attributes["platform.gce."+k] = strings.Trim(lastToken(value), "\n")
+	}
+
+	// Get internal and external IPs (if they exist)
+	value, err := f.Get("network-interfaces/", true)
+	var interfaces []GCEMetadataNetworkInterface
+	if err := json.Unmarshal([]byte(value), &interfaces); err != nil {
+		f.logger.Printf("[WARN] fingerprint.env_gce: Error decoding network interface information: %s", err.Error())
+	}
+
+	for _, intf := range interfaces {
+		prefix := "platform.gce.network." + lastToken(intf.Network)
+		node.Attributes[prefix] = "true"
+		node.Attributes[prefix+".ip"] = strings.Trim(intf.Ip, "\n")
+		for index, accessConfig := range intf.AccessConfigs {
+			node.Attributes[prefix+".external-ip."+strconv.Itoa(index)] = accessConfig.ExternalIp
+		}
+	}
+
+	var tagList []string
+	value, err = f.Get("tags", false)
+	if err != nil {
+		return false, checkError(err, f.logger, "tags")
+	}
+	if err := json.Unmarshal([]byte(value), &tagList); err != nil {
+		f.logger.Printf("[WARN] fingerprint.env_gce: Error decoding instance tags: %s", err.Error())
+	}
+	for _, tag := range tagList {
+		node.Attributes["platform.gce.tag."+tag] = "true"
+	}
+
+	var attrDict map[string]string
+	value, err = f.Get("attributes/", true)
+	if err != nil {
+		return false, checkError(err, f.logger, "attributes/")
+	}
+	if err := json.Unmarshal([]byte(value), &attrDict); err != nil {
+		f.logger.Printf("[WARN] fingerprint.env_gce: Error decoding instance attributes: %s", err.Error())
+	}
+	for k, v := range attrDict {
+		node.Attributes["platform.gce.attr."+k] = strings.Trim(v, "\n")
+	}
+
+	// populate Links
+	node.Links["gce"] = node.Attributes["platform.gce.id"]
+
+	return true, nil
+}
+
+func (f *EnvGCEFingerprint) isGCE() bool {
+	// TODO: better way to detect GCE?
+
+	// Query the metadata url for the machine type, to verify we're on GCE
+	machineType, err := f.Get("machine-type", false)
+	if err != nil {
+		if re, ok := err.(ReqError); !ok || re.StatusCode != 404 {
+			// If it wasn't a 404 error, print an error message.
+			f.logger.Printf("[ERR] fingerprint.env_gce: Error querying GCE Metadata URL, skipping")
+		}
+		return false
+	}
+
+	match, err := regexp.MatchString("projects/.+/machineTypes/.+", machineType)
+	if !match {
+		return false
+	}
+
+	return true
+}