gtsocial-umbx

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metadata.go (1332B)

      1 // Copyright 2014 Google Inc. All rights reserved.
      2 // Use of this source code is governed by the Apache 2.0
      3 // license that can be found in the LICENSE file.
      4 
      5 package internal
      6 
      7 // This file has code for accessing metadata.
      8 //
      9 // References:
     10 //	https://cloud.google.com/compute/docs/metadata
     11 
     12 import (
     13 	"fmt"
     14 	"io/ioutil"
     15 	"net/http"
     16 	"net/url"
     17 )
     18 
     19 const (
     20 	metadataHost = "metadata"
     21 	metadataPath = "/computeMetadata/v1/"
     22 )
     23 
     24 var (
     25 	metadataRequestHeaders = http.Header{
     26 		"Metadata-Flavor": []string{"Google"},
     27 	}
     28 )
     29 
     30 // TODO(dsymonds): Do we need to support default values, like Python?
     31 func mustGetMetadata(key string) []byte {
     32 	b, err := getMetadata(key)
     33 	if err != nil {
     34 		panic(fmt.Sprintf("Metadata fetch failed for '%s': %v", key, err))
     35 	}
     36 	return b
     37 }
     38 
     39 func getMetadata(key string) ([]byte, error) {
     40 	// TODO(dsymonds): May need to use url.Parse to support keys with query args.
     41 	req := &http.Request{
     42 		Method: "GET",
     43 		URL: &url.URL{
     44 			Scheme: "http",
     45 			Host:   metadataHost,
     46 			Path:   metadataPath + key,
     47 		},
     48 		Header: metadataRequestHeaders,
     49 		Host:   metadataHost,
     50 	}
     51 	resp, err := http.DefaultClient.Do(req)
     52 	if err != nil {
     53 		return nil, err
     54 	}
     55 	defer resp.Body.Close()
     56 	if resp.StatusCode != 200 {
     57 		return nil, fmt.Errorf("metadata server returned HTTP %d", resp.StatusCode)
     58 	}
     59 	return ioutil.ReadAll(resp.Body)
     60 }