// newClient creates http.Client with a jwt service account when
// jsonFile flag is specified, otherwise by obtaining the GCE service
// account's access token.
func newClient(jsonFile string) (*http.Client, error) {
if jsonFile != "" {
jsonKey, err := ioutil.ReadFile(jsonFile)
if err != nil {
return nil, err
}
conf, err := google.JWTConfigFromJSON(jsonKey, pubsub.ScopePubSub)
if err != nil {
return nil, err
}
return conf.Client(oauth2.NoContext), nil
}
if metadata.OnGCE() {
c := &http.Client{
Transport: &oauth2.Transport{
Source: google.ComputeTokenSource(""),
},
}
if *projID == "" {
projectID, err := metadata.ProjectID()
if err != nil {
return nil, fmt.Errorf("ProjectID failed, %v", err)
}
*projID = projectID
}
return c, nil
}
return nil, errors.New("Could not create an authenticated client.")
}
// NewComputeEngine constructs the credentials that fetches access tokens from
// Google Compute Engine (GCE)'s metadata server. It is only valid to use this
// if your program is running on a GCE instance.
// TODO(dsymonds): Deprecate and remove this.
func NewComputeEngine() credentials.Credentials {
return TokenSource{google.ComputeTokenSource("")}
}