terraform filter_policy sample
resource "aws_sns_topic_subscription" "sns-topic" {
topic_arn = "arn:aws:sns:${var.region}:${var.account_number}:${var.sns_topic_name}"
protocol = "sqs"
endpoint = "${aws_sqs_queue.sqs-queue.arn}"
filter_policy = <<EOF
{
"key": [{"prefix":"${var.prefix_filter}"}]
}
EOF
}