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|
package aws
import (
"encoding/json"
"io/ioutil"
"net/http"
"strings"
"time"
"github.com/pkg/errors"
"github.com/hairyhenderson/gomplate/v3/env"
)
// DefaultEndpoint -
var DefaultEndpoint = "http://169.254.169.254"
const (
// the default region
unknown = "unknown"
)
// Ec2Meta -
type Ec2Meta struct {
Endpoint string
Client *http.Client
nonAWS bool
cache map[string]string
options ClientOptions
}
// NewEc2Meta -
func NewEc2Meta(options ClientOptions) *Ec2Meta {
if endpoint := env.Getenv("AWS_META_ENDPOINT"); endpoint != "" {
DefaultEndpoint = endpoint
}
return &Ec2Meta{cache: make(map[string]string), options: options}
}
// returnDefault -
func returnDefault(def []string) string {
if len(def) > 0 {
return def[0]
}
return ""
}
func unreachable(err error) bool {
if strings.Contains(err.Error(), "request canceled") ||
strings.Contains(err.Error(), "no route to host") ||
strings.Contains(err.Error(), "host is down") {
return true
}
return false
}
// retrieve EC2 metadata, defaulting if we're not in EC2 or if there's a non-OK
// response. If there is an OK response, but we can't parse it, this errors
func (e *Ec2Meta) retrieveMetadata(url string, def ...string) (string, error) {
if value, ok := e.cache[url]; ok {
return value, nil
}
if e.nonAWS {
return returnDefault(def), nil
}
if e.Client == nil {
timeout := e.options.Timeout
if timeout == 0 {
timeout = 500 * time.Millisecond
}
e.Client = &http.Client{Timeout: timeout}
}
resp, err := e.Client.Get(url)
if err != nil {
if unreachable(err) {
e.nonAWS = true
}
return returnDefault(def), nil
}
// nolint: errcheck
defer resp.Body.Close()
if resp.StatusCode > 399 {
return returnDefault(def), nil
}
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
return "", errors.Wrapf(err, "Failed to read response body from %s", url)
}
value := strings.TrimSpace(string(body))
e.cache[url] = value
return value, nil
}
// Meta -
func (e *Ec2Meta) Meta(key string, def ...string) (string, error) {
if e.Endpoint == "" {
e.Endpoint = DefaultEndpoint
}
url := e.Endpoint + "/latest/meta-data/" + key
return e.retrieveMetadata(url, def...)
}
// Dynamic -
func (e *Ec2Meta) Dynamic(key string, def ...string) (string, error) {
if e.Endpoint == "" {
e.Endpoint = DefaultEndpoint
}
url := e.Endpoint + "/latest/dynamic/" + key
return e.retrieveMetadata(url, def...)
}
// Region -
func (e *Ec2Meta) Region(def ...string) (string, error) {
defaultRegion := returnDefault(def)
if defaultRegion == "" {
defaultRegion = unknown
}
doc, err := e.Dynamic("instance-identity/document", `{"region":"`+defaultRegion+`"}`)
if err != nil {
return "", err
}
obj := &InstanceDocument{
Region: defaultRegion,
}
err = json.Unmarshal([]byte(doc), &obj)
if err != nil {
return "", errors.Wrapf(err, "Unable to unmarshal JSON object %s", doc)
}
return obj.Region, nil
}
// InstanceDocument -
type InstanceDocument struct {
PrivateIP string `json:"privateIp"`
AvailabilityZone string `json:"availabilityZone"`
InstanceID string `json:"InstanceId"`
InstanceType string `json:"InstanceType"`
AccountID string `json:"AccountId"`
ImageID string `json:"imageId"`
Architecture string `json:"architecture"`
Region string `json:"region"`
}
|
