Scott Baker | e7144bc | 2019-10-01 14:16:47 -0700 | [diff] [blame^] | 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 | } |