com.amazonaws.services.s3.model.AmazonS3Exception: Status Code: 400, AWS Service: Amazon S3,
AWS Request ID: 7D8E4909FEACA905, AWS Error Code: InvalidRequest, AWS Error Message:
The authorization mechanism you have provided is not supported. Please use AWS4-HMAC-SHA256.

package com.databricks.spark.redshift

import com.databricks.spark.redshift.DefaultSource;
import org.apache.spark.sql.sources.BaseRelation;
import org.apache.spark.sql.{SparkSession, DataFrame, SQLContext}
import com.amazonaws.auth.AWSCredentialsProvider
import com.amazonaws.services.s3.AmazonS3Client

object RedshiftReaderM {
    val endpoint = "s3.ap-south-1.amazonaws.com"
    def getS3Client(provider:AWSCredentialsProvider):AmazonS3Client = {
        val client = new AmazonS3Client(provider);
        client.setEndpoint(endpoint);
        client
    }
    def getDataFrameForConfig(configs:Map[String,String], sparkSession:SparkSession):DataFrame = {
        val sqlContext = sparkSession.sqlContext
        val source:DefaultSource = new DefaultSource(new JDBCWrapper(),getS3Client)
        val br:BaseRelation = source.createRelation(sqlContext, configs)
        sparkSession.baseRelationToDataFrame(br);
    }
}

import com.databricks.spark.redshift._

sc.hadoopConfiguration.set("fs.s3a.endpoint","s3.ap-south-1.amazonaws.com")
System.setProperty("com.amazonaws.services.s3.enableV4", "true")

val options = Map(  "query" -> "select * from tbl limit 10",
                    "url"   -> "jdbc:redshift:/<redshift-host>:5439/<database>?user=<user>&password=<password>",
                    "tempdir" -> "s3a://bucket/ks1/ks2/",
                    "aws_iam_role" -> "arn:aws:iam::<accountid>:role/<iam-role>"
                )
val df = RedshiftReaderM.getDataFrameForConfig(options, spark)
df.show