What permissions in IAM do i need to start EC2 instances with chef knife?

Q1: I had to debug knife-ec2 gem in order to find out the minimal IAM permissions required to start an EC2 instance. Here is the minimal policy:

{
  "Statement": [
    {
      "Sid": "Stmt123",
      "Action": [
        "ec2:RunInstances",
        "ec2:DescribeInstances",
        "ec2:DescribeKeyPairs",
        "ec2:DescribeImages",
        "ec2:CreateTags",
        "ec2:DescribeTags"
      ],
      "Effect": "Allow",
      "Resource": [
        "*"
      ]
    }
  ]
}

Please note the Sid should be unique.

Q2: My knowledge of Ruby is quite limited so possibly there is not convenient way for debugging. Personally I used binding.pry as a debugger. Please refer to the following article for more info.

You will need to allow RunInstances.