Needed Trust Relationship for what is described in http://marcelog.github.io/articles/aws_cloudwatch_event_rule_serverless_replace_crontab.html

aws_trust_relationship.json

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": [
          "events.amazonaws.com",
          "lambda.amazonaws.com"
        ]
      },
      "Action": "sts:AssumeRole"
    }
  ]
}