title: Sending credentials to Google Dataflow jobs
body: <p>What is the right way to pass credentials to Dataflow jobs?</p>
  
  <p>Some of my Dataflow jobs need credentials to make REST calls and fetch/post processed data.</p>
  
  <p>I am currently using environment variables to pass the credentials to the JVM, read them into a Serializable object and pass them on to the DoFn implementation's constructor. I am not sure this is the right approach as any class which is Serializable should not contain sensitive information.</p>
  
  <p>Another way I thought of is to store the credential in GCS and retrieve them using service account key file, but was wondering why should my job execute this task of reading credentials from GCS.</p>