xdr-terraform-modules/base/splunk_servers/searchhead/main.tf

# Some instance variables
locals {
  ami_selection         = "minion" # master, minion, ...
  instance_name         = var.instance_name != "" ? var.instance_name : "${var.prefix}-splunk-sh"
  alb_name              = var.alb_name != "" ? var.alb_name : "${var.prefix}-splunk"
  is_moose              = length(regexall("moose", var.prefix)) > 0 ? true : false
  is_monitoring_console = var.alb_name == "splunk-mc" ? true : false
  is_fm_searchhead      = var.alb_name == "fm-shared-search" ? true : false
}

# 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.searchhead_security_group.id]
  description     = local.instance_name
  tags            = merge(local.standard_tags, var.tags, { Name = local.instance_name })
}

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                        = local.instance_type
  key_name                             = "msoc-build"
  monitoring                           = false
  iam_instance_profile                 = local.is_moose ? module.moose_instance_profile[0].profile_id : "splunk-sh-instance-profile"

  metadata_options {
    http_endpoint = "enabled"
    http_tokens = "optional" # tfsec:ignore:aws-ec2-enforce-http-token-imds Splunk uses v1 by default. MSOCI-2150
  }

  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           = "gp2"
    volume_size           = local.volume_sizes["/"]
    delete_on_termination = true
    encrypted             = true
    kms_key_id            = data.aws_kms_key.ebs-key.arn
  }

  ebs_block_device {
    # /opt/splunk
    # Note: Not in AMI
    device_name           = "/dev/xvdf"
    volume_size           = local.volume_sizes["/opt/splunk"]
    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_size           = local.volume_sizes["swap"]
    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_size           = local.volume_sizes["/home"]
    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           = local.volume_sizes["/var"]
    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_size           = local.volume_sizes["/var/tmp"]
    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_size           = local.volume_sizes["/var/log"]
    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_size           = local.volume_sizes["/var/log/audit"]
    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_size           = local.volume_sizes["/tmp"]
    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.cloud-init.rendered
  tags        = merge(local.standard_tags, var.tags, var.instance_tags, { Name = local.instance_name })
  volume_tags = merge(local.standard_tags, var.tags, { Name = local.instance_name })

  depends_on = [module.moose_instance_profile, module.instance_profile]
}

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

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

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

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

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

  # mount /dev/xvdf at /opt/splunk
  part {
    content_type = "text/cloud-boothook"
    content      = file("${path.module}/cloud-init/opt_splunk.boothook")
  }
}

## Searchhead
#
# Summary:
#   Ingress:
#     tcp/8000      - Splunk Web                 - vpc-access, legacy openvpn, legacy bastion, Phantom
#     tcp/8000      - Splunk Web                 - Entire VPC + local.splunk_legacy_cidr
#     tcp/8089      - Splunk API                 - vpc-access, legacy openvpn, legacy bastion, Phantom
#     tcp/8089      - Splunk API + IDX Discovery - Entire VPC + local.splunk_legacy_cidr 
#     tcp/9997-9998 - Splunk Data                - Entire VPC + local.splunk_legacy_cidr
#
#   Ingress:
#     tcp/8000      - Splunk Web                 - vpc-system-services (for salt inventory (moose only))
#     tcp/8089      - Splunk Web                 - vpc-system-services (for salt inventory and portal lambda)
#
#   Egress:
#     tcp/8089      - Splunk API + IDX Discovery - Entire VPC + local.splunk_legacy_cidr
resource "aws_security_group" "searchhead_security_group" {
  name        = "${var.prefix}_searchhead_security_group"
  description = "Security Group for Splunk Searchhead Instance(s)"
  vpc_id      = var.vpc_id
  tags        = merge(local.standard_tags, var.tags)
}

# Ingress
resource "aws_security_group_rule" "splunk-web-in" {
  description = "Web access"
  type        = "ingress"
  from_port   = 8000
  to_port     = 8000
  protocol    = "tcp"
  cidr_blocks = toset(concat(local.cidr_map["vpc-access"],
    local.cidr_map["vpc-private-services"],
    local.splunk_legacy_cidr,
    [var.vpc_cidr],
    local.is_moose ? local.cidr_map["vpc-system-services"] : [], # for salt inventory
  ))
  security_group_id = aws_security_group.searchhead_security_group.id
}

resource "aws_security_group_rule" "splunk-api-in" {
  description = "Splunk API"
  type        = "ingress"
  from_port   = 8089
  to_port     = 8089
  protocol    = "tcp"
  cidr_blocks = toset(concat(local.cidr_map["vpc-access"],
    local.cidr_map["vpc-private-services"],
    local.cidr_map["vpc-splunk"], # MC
    local.splunk_legacy_cidr,
    [var.vpc_cidr],
    local.cidr_map["vpc-system-services"], # for salt inventory and Portal lambda
  ))
  security_group_id = aws_security_group.searchhead_security_group.id
}

# Egress
resource "aws_security_group_rule" "ssh-out" {
  count             = length(local.splunk_legacy_cidr) > 0 ? 1 : 0
  description       = "SSH to legacy splunk"
  type              = "egress"
  from_port         = 22
  to_port           = 22
  protocol          = "tcp"
  cidr_blocks       = local.splunk_legacy_cidr
  security_group_id = aws_security_group.searchhead_security_group.id
}

resource "aws_security_group_rule" "splunk-api-out" {
  description       = "Splunk API Outbound to talk to indexers"
  type              = "egress"
  from_port         = 8089
  to_port           = 8089
  protocol          = "tcp"
  cidr_blocks       = toset(concat([var.vpc_cidr], local.splunk_legacy_cidr))
  security_group_id = aws_security_group.searchhead_security_group.id
}

resource "aws_security_group_rule" "splunk-api-out-to-all" {
  count             = local.is_monitoring_console || local.is_fm_searchhead ? 1 : 0
  description       = "Splunk API Outbound to talk to Other Segments"
  type              = "egress"
  from_port         = 8089
  to_port           = 8089
  protocol          = "tcp"
  cidr_blocks       = ["10.0.0.0/8"]
  security_group_id = aws_security_group.searchhead_security_group.id
}

resource "aws_security_group_rule" "splunk-data-out" {
  description       = "Splunk Data Outbound to talk to own indexers"
  type              = "egress"
  from_port         = 9997
  to_port           = 9998
  protocol          = "tcp"
  cidr_blocks       = toset(concat([var.vpc_cidr], local.splunk_legacy_cidr))
  security_group_id = aws_security_group.searchhead_security_group.id
}