xdr-terraform-modules/base/salt_master/main.tf

# Some instance variables
locals {
  ami_selection = "master" # master, minion, ...
}

# Rather than pass in the aws security group, we just look it up. This will
# probably be useful other places, as well.
data "aws_security_group" "typical-host" {
  name   = "typical-host"
  vpc_id = var.vpc_id
}

# Use the default EBS key
data "aws_kms_key" "ebs-key" {
  key_id = "alias/ebs_root_encrypt_decrypt"
}

resource "aws_network_interface" "instance" {
  subnet_id       = var.subnets[0]
  security_groups = [data.aws_security_group.typical-host.id, aws_security_group.salt_master_security_group.id]
  description     = var.instance_name
  tags            = merge(local.standard_tags, var.tags, { Name = var.instance_name })
}

resource "aws_eip" "instance" {
  vpc  = true
  tags = merge(local.standard_tags, var.tags, { Name = var.instance_name })
}

resource "aws_eip_association" "instance" {
  network_interface_id = aws_network_interface.instance.id
  allocation_id        = aws_eip.instance.id
}

resource "aws_instance" "instance" {
  #availability_zone = var.azs[count.index % 2]
  tenancy                              = "default"
  ebs_optimized                        = true
  disable_api_termination              = var.instance_termination_protection
  instance_initiated_shutdown_behavior = "stop"
  instance_type                        = var.environment == "prod" ? "t3a.xlarge" : "t3a.large"
  key_name                             = "msoc-build"
  monitoring                           = false # checkov:skip=CKV_AWS_126:Detailed monitoring not needed at this time
  iam_instance_profile                 = "salt-master-instance-profile"

  metadata_options {
    http_endpoint = "enabled"
    # tfsec:ignore:aws-ec2-enforce-http-token-imds Saltstack doesn't use s3 sources appropriately; see https://github.com/saltstack/salt/issues/60668
    http_tokens   = "optional"
  }

  ami = local.ami_map[local.ami_selection]
  # We need to ignore ebs_block_device changes, because if the AMI changes, so does the snapshot_id.
  # If they add a feature to block more specific changes (eg `ebs_block_devices[*].snapshot_id`), then
  # that could be removed.
  lifecycle { ignore_changes = [ami, key_name, user_data, ebs_block_device] }

  # These device definitions are optional, but added for clarity.
  root_block_device {
    volume_type = "gp3"
    #volume_size = "60"
    delete_on_termination = true
    encrypted             = true
    kms_key_id            = data.aws_kms_key.ebs-key.arn
  }

  ebs_block_device {
    # swap
    device_name           = "/dev/xvdm"
    volume_type           = "gp3"
    volume_size           = 48
    delete_on_termination = true
    encrypted             = true
    kms_key_id            = data.aws_kms_key.ebs-key.arn
    # Snapshot IDs need to be grabbed from the ami, or it will replace every time. It's ugly.
    # This may prompt replacement when the AMI is updated.
    # See:
    #   https://github.com/hashicorp/terraform/issues/19958
    #   https://github.com/terraform-providers/terraform-provider-aws/issues/13118
    snapshot_id = local.block_device_mappings[local.ami_selection]["/dev/xvdm"].ebs.snapshot_id
  }
  ebs_block_device {
    # /home
    device_name = "/dev/xvdn"
    volume_type = "gp3"
    # volume_size = xx
    delete_on_termination = true
    encrypted             = true
    kms_key_id            = data.aws_kms_key.ebs-key.arn
    snapshot_id           = local.block_device_mappings[local.ami_selection]["/dev/xvdn"].ebs.snapshot_id

  }
  ebs_block_device {
    # /var
    device_name           = "/dev/xvdo"
    volume_size           = 30
    volume_type           = "gp3"
    delete_on_termination = true
    encrypted             = true
    kms_key_id            = data.aws_kms_key.ebs-key.arn
    snapshot_id           = local.block_device_mappings[local.ami_selection]["/dev/xvdo"].ebs.snapshot_id
  }
  ebs_block_device {
    # /var/tmp
    device_name = "/dev/xvdp"
    volume_type = "gp3"
    # volume_size = xx
    delete_on_termination = true
    encrypted             = true
    kms_key_id            = data.aws_kms_key.ebs-key.arn
    snapshot_id           = local.block_device_mappings[local.ami_selection]["/dev/xvdp"].ebs.snapshot_id
  }
  ebs_block_device {
    # /var/log
    device_name = "/dev/xvdq"
    volume_type = "gp3"
    # volume_size = xx
    delete_on_termination = true
    encrypted             = true
    kms_key_id            = data.aws_kms_key.ebs-key.arn
    snapshot_id           = local.block_device_mappings[local.ami_selection]["/dev/xvdq"].ebs.snapshot_id
  }
  ebs_block_device {
    # /var/log/audit
    device_name = "/dev/xvdr"
    volume_type = "gp3"
    # volume_size = xx
    delete_on_termination = true
    encrypted             = true
    kms_key_id            = data.aws_kms_key.ebs-key.arn
    snapshot_id           = local.block_device_mappings[local.ami_selection]["/dev/xvdr"].ebs.snapshot_id
  }
  ebs_block_device {
    # /tmp
    device_name = "/dev/xvds"
    volume_type = "gp3"
    # volume_size = xx
    delete_on_termination = true
    encrypted             = true
    kms_key_id            = data.aws_kms_key.ebs-key.arn
    snapshot_id           = local.block_device_mappings[local.ami_selection]["/dev/xvds"].ebs.snapshot_id
  }

  network_interface {
    device_index         = 0
    network_interface_id = aws_network_interface.instance.id
  }

  user_data   = data.template_cloudinit_config.salt_master_cloud_init_config.rendered
  tags        = merge(local.standard_tags, var.tags, var.instance_tags, { Name = var.instance_name })
  volume_tags = merge(local.standard_tags, var.tags, { Name = var.instance_name })
}

module "private_dns_record" {
  source = "../../submodules/dns/private_A_record"

  name            = var.instance_name
  ip_addresses    = [aws_instance.instance.private_ip]
  dns_info        = var.dns_info
  reverse_enabled = var.reverse_enabled

  providers = {
    aws.c2 = aws.c2
  }
}

module "public_dns_record" {
  source = "../../submodules/dns/public_A_record"

  name         = var.instance_name
  ip_addresses = [aws_eip.instance.public_ip]
  dns_info     = var.dns_info

  providers = {
    aws.mdr-common-services-commercial = aws.mdr-common-services-commercial
  }
}

# Render a multi-part cloud-init config making use of the part
# above, and other source files
data "template_cloudinit_config" "salt_master_cloud_init_config" {
  gzip          = true
  base64_encode = true

  # Main cloud-config configuration file.
  part {
    filename     = "init.cfg"
    content_type = "text/cloud-config"
    content = templatefile("${path.module}/cloud-init/cloud_init_salt_master.tpl",
      {
        hostname            = var.instance_name
        fqdn                = "${var.instance_name}.${var.dns_info["private"]["zone"]}"
        environment         = var.environment
        salt_master         = local.salt_master
        proxy               = local.proxy
        aws_partition       = var.aws_partition
        aws_partition_alias = var.aws_partition_alias
        aws_region          = var.aws_region
      }
    )
  }

  # Additional parts as needed
  part {
    content_type = "text/x-shellscript"
    content      = file("${path.module}/cloud-init/provision_salt_master.sh")
  }
}

#----------------------------------------------------------------------------
# Salt Master Security Group
#----------------------------------------------------------------------------
resource "aws_security_group" "salt_master_security_group" {
  name        = "salt_master_security_group"
  description = "Security Group for Salt Master(s)"
  vpc_id      = var.vpc_id
  tags        = merge(local.standard_tags, var.tags)
}

#----------------------------------------------------------------------------
# Egress
#----------------------------------------------------------------------------
resource "aws_security_group_rule" "http-out" {
  type              = "egress"
  description       = "HTTP - Outbound - For endpoints and troubleshooting"
  from_port         = 80
  to_port           = 80
  protocol          = "tcp"
  cidr_blocks       = ["10.0.0.0/8"]
  security_group_id = aws_security_group.salt_master_security_group.id
}

resource "aws_security_group_rule" "https-out" {
  type              = "egress"
  description       = "HTTPS - Outbound - For endpoints and troubleshooting"
  from_port         = 443
  to_port           = 443
  protocol          = "tcp"
  cidr_blocks       = ["10.0.0.0/8"]
  security_group_id = aws_security_group.salt_master_security_group.id
}

#----------------------------------------------------------------------------
# Ingress
#----------------------------------------------------------------------------
resource "aws_security_group_rule" "saltstack" {
  type              = "ingress"
  description       = "SaltStack"
  from_port         = "4505"
  to_port           = "4506"
  protocol          = "tcp"
  cidr_blocks       = ["10.0.0.0/8"]
  security_group_id = aws_security_group.salt_master_security_group.id
}

resource "aws_security_group_rule" "saltstack-external-ips" {

  # This deserves some explanation.  Terraform "for_each" expects to be
  # getting as input a map of values to iterate over as part of the foreach.
  # The keys of the map are used to name each of these objects created.  Looking
  # in the terraform plan output of a for_each you'll see things like:
  #
  # aws_security_group_rule.resource_name["key-value-from-foreach"] will be created
  #
  # Our c2_services_external_ips is a list of maps, not a map of maps.  The for-expression
  # makes a new thing that is a map of maps, where the key value is the description with
  # blanks removed.
  #
  # We could have made the variable more natively-friendly to for_each but this seemed
  # like a better solution for what we were trying to accomplish.
  for_each = { for s in local.c2_services_external_ips : replace(s.description, "/\\s*/", "") => s }

  description       = "Saltstack - ${each.value.description}"
  type              = "ingress"
  from_port         = "4505"
  to_port           = "4506"
  protocol          = "tcp"
  cidr_blocks       = each.value.cidr_blocks # tfsec:ignore:aws-vpc-no-public-ingress-sgr Intentionally allow inbound
  security_group_id = aws_security_group.salt_master_security_group.id
}

#----------------------------------------------------------------------------
# Egress
#----------------------------------------------------------------------------
#TODO: make this better
#for now, just allow 22 outbound anywhere
resource "aws_security_group_rule" "saltstack-github" {
  type              = "egress"
  description       = "SaltStack - Github Access"
  from_port         = "22"
  to_port           = "22"
  protocol          = "tcp"
  cidr_blocks       = ["0.0.0.0/0"] # tfsec:ignore:aws-vpc-no-public-egress-sgr direct access for github
  security_group_id = aws_security_group.salt_master_security_group.id
}