This stage sets up an area dedicated to hosting security resources and configurations which impact the whole organization, or are shared across the hierarchy to other projects and teams.

The design of this stage is fairly general, and out of the box it only provides a reference example for Cloud KMS.

Expanding it to include other security-related services like Secret Manager is fairly simple by adapting the provided implementation for Cloud KMS, and leveraging the broad permissions granted on the top-level Security folder to the automation service account used here.

The following diagram illustrates the high-level design of resources managed here:

Design overview and choices
- Cloud KMS
- Certificate Authority Service (CAS)
How to run this stage
Customizations
- KMS keys
- NGFW Enterprise - sample TLS configurations
Files
Variables
Outputs

Design overview and choices

Project-level security resources are grouped into two separate projects, one per environment. This setup matches requirements we frequently observe in real life and provides enough separation without needlessly complicating operations.

Cloud KMS is configured and designed mainly to encrypt GCP resources with a Customer-managed encryption key but it may be used to create cryptokeys used to encrypt application data too.

IAM for day to day operations is already assigned at the folder level to the security team by the previous stage, but more granularity can be added here at the project level, to grant control of separate services across environments to different actors.

Cloud KMS

A reference Cloud KMS implementation is part of this stage, to provide a simple way of managing centralized keys, that are then shared and consumed widely across the organization to enable customer-managed encryption. The implementation is also easy to clone and modify to support other services like Secret Manager.

The Cloud KMS configuration allows defining keys by name (typically matching the downstream service that uses them) in different locations. It then takes care internally of provisioning the relevant keyrings and creating keys in the appropriate location.

IAM roles on keys can be configured at the logical level for all locations where a logical key is created. Their management can also be delegated via delegated role grants exposed through a simple variable, to allow other identities to set IAM policies on keys. This is particularly useful in setups like project factories, making it possible to configure IAM bindings during project creation for team groups or service agent accounts (compute, storage, etc.).

Certificate Authority Service (CAS)

With this stage you can leverage Certificate Authority Services (CAS) and create as many CAs you need for each environments. To create custom CAS, you can use the certificate_authorities variable.

How to run this stage

This stage is meant to be executed after the bootstrap stage has run, as it leverages the automation service account and bucket created there, and additional resources configured there.

It's of course possible to run this stage in isolation, but that's outside the scope of this document, and you would need to refer to the code for the previous stages for the environmental requirements.

Before running this stage, you need to make sure you have the correct credentials and permissions, and localize variables by assigning values that match your configuration.

Provider and Terraform variables

As all other FAST stages, the mechanism used to pass variable values and pre-built provider files from one stage to the next is also leveraged here.

The commands to link or copy the provider and terraform variable files can be easily derived from the fast-links.sh script in the FAST stages folder, passing it a single argument with the local output files folder (if configured) or the GCS output bucket in the automation project (derived from stage 0 outputs). The following examples demonstrate both cases, and the resulting commands that then need to be copy/pasted and run.

../fast-links.sh ~/fast-config

# File linking commands for security stage

# provider file
ln -s ~/fast-config/fast-test-00/providers/2-security-providers.tf ./

# input files from other stages
ln -s ~/fast-config/fast-test-00/tfvars/0-globals.auto.tfvars.json ./
ln -s ~/fast-config/fast-test-00/tfvars/0-org-setup.auto.tfvars.json ./
ln -s ~/fast-config/fast-test-00/tfvars/1-resman.auto.tfvars.json ./

# conventional place for stage tfvars (manually created)
ln -s ~/fast-config/fast-test-00/2-security.auto.tfvars ./

# optional files
ln -s ~/fast-config/fast-test-00/2-nsec.auto.tfvars.json ./

../fast-links.sh gs://xxx-prod-iac-core-outputs-0

# File linking commands for security stage

# provider file
gcloud storage cp gs://xxx-prod-iac-core-outputs-0/providers/2-security-providers.tf ./

# input files from other stages
gcloud storage cp gs://xxx-prod-iac-core-outputs-0/tfvars/0-globals.auto.tfvars.json ./
gcloud storage cp gs://xxx-prod-iac-core-outputs-0/tfvars/0-org-setup.auto.tfvars.json ./
gcloud storage cp gs://xxx-prod-iac-core-outputs-0/tfvars/1-resman.auto.tfvars.json ./

# conventional place for stage tfvars (manually created)
gcloud storage cp gs://xxx-prod-iac-core-outputs-0/2-security.auto.tfvars ./

# optional files
gcloud storage cp gs://xxx-prod-iac-core-outputs-0/2-nsec.auto.tfvars.json ./

Impersonating the automation service account

The preconfigured provider file uses impersonation to run with this stage's automation service account's credentials. The gcp-devops and organization-admins groups have the necessary IAM bindings in place to do that, so make sure the current user is a member of one of those groups.

Variable configuration

Variables in this stage -- like most other FAST stages -- are broadly divided into three separate sets:

variables which refer to global values for the whole organization (org id, billing account id, prefix, etc.), which are pre-populated via the 0-globals.auto.tfvars.json file linked or copied above
variables which refer to resources managed by previous stages, which are prepopulated here via the 0-org-setup.auto.tfvars.json and 1-resman.auto.tfvars.json files linked or copied above
and finally variables that optionally control this stage's behaviour and customizations, and can to be set in a custom terraform.tfvars file

The latter set is explained in the Customization sections below, and the full list can be found in the Variables table at the bottom of this document.

Note that the outputs_location variable is disabled by default, you need to explicitly set it in your terraform.tfvars file if you want output files to be generated by this stage. This is a sample terraform.tfvars that configures it, refer to the bootstrap stage documentation for more details:

outputs_location = "~/fast-config"

Using delayed billing association for projects

This configuration is possible but unsupported and only exists for development purposes, use at your own risk:

temporarily switch billing_account.id to null in 0-globals.auto.tfvars.json
for each project resources in the project modules used in this stage (dev-sec-project, prod-sec-project)
- apply using -target, for example terraform apply -target 'module.prod-sec-project.google_project.project[0]'
- untaint the project resource after applying, for example terraform untaint 'module.prod-sec-project.google_project.project[0]'
go through the process to associate the billing account with the two projects
switch billing_account.id back to the real billing account id
resume applying normally

Running the stage

Once provider and variable values are in place and the correct user is configured, the stage can be run:

terraform init
terraform apply

Customizations

KMS keys

Cloud KMS configuration is controlled by kms_keys, which configures the actual keys to create, and also allows configuring their IAM bindings, labels, locations and rotation period. When configuring locations for a key, please consider the limitations each cloud product may have.

The additional kms_restricted_admins variable allows granting roles/cloudkms.admin to specified principals, restricted via delegated role grants so that it only allows granting the roles needed for encryption/decryption on keys. This allows safe delegation of key management to subsequent Terraform stages like the Project Factory, for example to grant usage access on relevant keys to the service agent accounts for compute, storage, etc.

To support these scenarios, key IAM bindings are configured by default to be additive, to enable other stages or Terraform configuration to safely co-manage bindings on the same keys. If this is not desired, follow the comments in the core-dev.tf and core-prod.tf files to switch to authoritative bindings on keys.

An example of how to configure keys:

# terraform.tfvars

kms_keys = {
  compute = {
    iam = {
      "roles/cloudkms.cryptoKeyEncrypterDecrypter" = [
        "user:user1@example.com"
      ]
    }
    labels          = { service = "compute" }
    locations       = ["europe-west1", "europe-west3", "global"]
    rotation_period = "7776000s"
  }
  storage = {
    iam             = null
    labels          = { service = "storage" }
    locations       = ["europe"]
    rotation_period = null
  }
}

The script will create one keyring for each specified location and keys on each keyring.

NGFW Enterprise - sample TLS configurations

This is a minimal configuration that creates a CAs for each environment and enables TLS inspection policies for NGFW Enterprise.

cas_configs = {
  dev = {
    ngfw-dev-cas-0 = {
      location = "europe-west1"
    }
  }
  prod = {
    ngfw-prod-cas-0 = {
      location = "europe-west1"
    }
  }
}
tls_inspection = {
  enabled = true
}

You can optionally create also trust-configs for NGFW Enterprise.

cas_configs = {
  dev = {
    ngfw-dev-cas-0 = {
      location = "europe-west1"
    }
  }
  prod = {
    ngfw-prod-cas-0 = {
      location = "europe-west1"
    }
  }
}
trust_configs = {
  dev = {
    ngfw-dev-tc-0 = {
      allowlisted_certificates = {
        my_ca = "~/my_keys/srv-dev.crt"
      }
      location = "europe-west1"
    }
  }
  prod = {
    ngfw-prod-tc-0 = {
      allowlisted_certificates = {
        my_ca = "~/my_keys/srv-prod.crt"
      }
      location = "europe-west1"
    }
  }
}
tls_inspection = {
  enabled = true
}

You can customize the keys of your configurations, as long as they match the ones you specify in the ngfw_tls_configs.keys variable.

cas_configs = {
  dev = {
    my-ca-0 = {
      location = "europe-west1"
    }
  }
}
ngfw_tls_configs = {
  keys = {
    dev = {
      cas = "my-ca-0"
    }
  }
}
tls_inspection = {
  enabled = true
}

Files

name	description	modules	resources
cas.tf	Per-environment certificate resources.	`certificate-authority-service`
kms.tf	Per-environment KMS.
main.tf	Module-level locals and resources.	`folder` · `project`
outputs.tf	Module outputs.		`google_storage_bucket_object` · `local_file`
variables-fast.tf	None
variables.tf	Module variables.

Variables

name	description	type	required	default	producer
automation	Automation resources created by the bootstrap stage.	`object({…})`	✓		`0-org-setup`
billing_account	Billing account id. If billing account is not part of the same org set `is_org_level` to false.	`object({…})`	✓		`0-org-setup`
folder_ids	Folder name => id mappings, the 'security' folder name must exist.	`object({…})`	✓		`1-resman`
prefix	Prefix used for resources that need unique names. Use a maximum of 9 chars for organizations, and 11 chars for tenants.	`string`	✓		`0-org-setup`
certificate_authorities	Certificate Authority Service pool and CAs. If environments is null identical pools and CAs are created in all environments.	`map(object({…}))`		`{}`
environments	Environment names.	`map(object({…}))`		`{…}`	`0-globals`
essential_contacts	Email used for essential contacts, unset if null.	`string`		`null`
kms_keys	KMS keys to create, keyed by name.	`map(object({…}))`		`{}`
outputs_location	Path where providers, tfvars files, and lists for the following stages are written. Leave empty to disable.	`string`		`null`
stage_configs	FAST stage configuration.	`object({…})`		`{}`	`1-resman`
tag_values	Root-level tag values.	`map(string)`		`{}`	`1-resman`

Outputs

name	description	sensitive
certificate_authority_pools	Certificate Authority Service pools and CAs.
kms_keys	KMS key ids.
tfvars	Terraform variable files for the following stages.	✓