Packer IAM Role in Terraform

packer_iam.tf

data "aws_caller_identity" "current" {}
data "aws_region" "current" {}

locals {
  rolename = "${local.identifier}-${data.aws_region.current.name}"
}


data "aws_iam_policy_document" "packer" {

  # Global ECS Permissions Statement
  statement {
    actions = [
      "ec2:Describe*",
      "ec2:CreateKeyPair",
      "ec2:DeleteKeyPair",
      "ec2:CreateImage",
      "ec2:DescribeKeyPairs",
      "ec2:CreateSecurityGroup",
      "iam:GetInstanceProfiles",
      "iam:ListInstanceProfiles",
      "ec2:CreateTags"
    ]
    resources = ["*"]
  }

  # Be able to pass role to instance
  statement {
    actions = [
      "iam:PassRole"
    ]
    resources = ["arn:aws:iam::${data.aws_caller_identity.current.account_id}:role/${local.rolename}"]
  }

  # Manage instances but only if they have this profile
  statement {
    actions = [
      "ec2:RunInstances",
      "ec2:StartInstances",
      "ec2:StopInstances",
      "ec2:RebootInstances",
      "ec2:TerminateInstances",
      "ec2:ModifyInstanceAttribute",
      "ec2:GetPasswordData",
      "ec2:AttachVolume",
      "ec2:DetachVolume",
      "ec2:CreateSnapshot",
      "ec2:DeleteSnaphot",
      "ec2:AuthorizeSecurityGroup*",
      "ec2:RevokeSecurityGroup*"
    ]

    condition {
      test     = "StringEquals"
      variable = "ec2:InstanceProfile"
      values   = ["arn:aws:iam::${data.aws_caller_identity.current.account_id}:instance-profile/${local.rolename}"]
    }

    resources = ["arn:aws:ec2:${data.aws_region.current.name}:${data.aws_caller_identity.current.account_id}:instance/*"]
  }


  # Running instances requires access to a lot of resources
  statement {
    actions = [
      "ec2:RunInstances"
    ]

    resources = [
      "arn:aws:ec2:${data.aws_region.current.name}:${data.aws_caller_identity.current.account_id}:subnet/*",
      "arn:aws:ec2:${data.aws_region.current.name}:${data.aws_caller_identity.current.account_id}:volume/*",
      "arn:aws:ec2:${data.aws_region.current.name}::image/*",
      "arn:aws:ec2:${data.aws_region.current.name}::snapshot/*",
      "arn:aws:ec2:${data.aws_region.current.name}:${data.aws_caller_identity.current.account_id}:network-interface/*",
      "arn:aws:ec2:${data.aws_region.current.name}:${data.aws_caller_identity.current.account_id}:key-pair/*",
      "arn:aws:ec2:${data.aws_region.current.name}:${data.aws_caller_identity.current.account_id}:security-group/*"
    ]
  }
}

resource "aws_iam_policy" "packer" {
  name        = "${local.rolename}-policy"
  path        = "/"
  description = "Packer Policy"
  policy      = data.aws_iam_policy_document.packer.json
}


#
# Create role for IAM Instance
#

resource "aws_iam_role" "packer" {
  name = local.rolename

  # Allow EC2 instances to use this role.
  assume_role_policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": "sts:AssumeRole",
      "Principal": {
        "Service": "ec2.amazonaws.com"
      },
      "Effect": "Allow",
      "Sid": ""
    }
  ]
}
EOF
}

resource "aws_iam_role_policy_attachment" "packer-policy" {
  role       = aws_iam_role.packer.name
  policy_arn = aws_iam_policy.packer.arn
}


# Add an instance profile. These are created automatically in the console but not in terraform.
resource "aws_iam_instance_profile" "test_profile" {
  name = aws_iam_role.packer.name
  role = aws_iam_role.packer.name
}