$ cd $DEMO/alluxio-1.8.1
$ export AWS_ACCESS_KEY=YOUR_ACCESS_KEY
$ export AWS_SECRET_KEY=YOUR_SECRET_KEY
$ vi conf/alluxio-env.sh

# Modify the ALLUXIO_JAVA_OPTS to add the two parameters
export ALLUXIO_JAVA_OPTS+="
-Dlog4j.configuration=file:${CONF_DIR}/log4j.properties
...
-Dfs.s3n.awsAccessKeyId=$AWS_ACCESS_KEY
-Dfs.s3n.awsSecretAccessKey=$AWS_SECRET_KEY
"