How to use

getCredentials

method

in

org.apache.hadoop.mapreduce.Mapper$Context

throws IOException, InterruptedException {
 Credentials ts = context.getCredentials();
 Collection<Token<? extends TokenIdentifier>> dts = ts.getAllTokens();

 /**
  * attempts to access tokenCache as from client
  */
 @Override
 public void map(IntWritable key, IntWritable value, Context context)
 throws IOException, InterruptedException {
  // get token storage and a key
  Credentials ts = context.getCredentials();
  byte[] key1 = ts.getSecretKey(new Text("alias1"));
  Collection<Token<? extends TokenIdentifier>> dts = ts.getAllTokens();
  int dts_size = 0;
  if(dts != null)
   dts_size = dts.size();
  
  
  if(dts_size != 2) { // one job token and one delegation token
   throw new RuntimeException("tokens are not available"); // fail the test
  }
  
  
  if(key1 == null || ts == null || ts.numberOfSecretKeys() != NUM_OF_KEYS) {
   throw new RuntimeException("secret keys are not available"); // fail the test
  } 
  super.map(key, value, context);
 }
}

throws IOException, InterruptedException {
 final Credentials contextCredentials = context.getCredentials();

protected void setup(Context context) 
throws IOException, InterruptedException {
 ts = context.getCredentials();
}