What We Realized from Constructing GovSlack

Slack launched GovSlack in July 2022. With GovSlack, authorities companies, and people they work with, can allow their groups to seamlessly collaborate of their digital headquarters, whereas protecting safety and compliance on the forefront. Utilizing GovSlack consists of the next advantages:

• Helps key authorities safety requirements, reminiscent of FedRAMP Excessive, DoD IL4, and ITAR
• Runs in AWS GovCloud information facilities
• Permits exterior collaboration with different GovSlack-using organizations by means of Slack Join
• Supplies entry to your individual set of encryption keys for superior auditing and logging controls
• Permits permission and entry controls at scale by means of Slack’s enterprise-grade admin dashboard
• Features a listing of curated functions (together with DLP and eDiscovery apps) that may combine with Slack
• Maintained and supported by US personnel

Earlier than the massive launch, the Cloud Foundations crew spent virtually two quarters organising the infrastructure wanted to run GovSlack.

GovSlack is the very first service Slack launched on AWS Gov infrastructure. Due to this fact we needed to spend a major period of time studying the variations between normal and Gov AWS and making modifications to our tooling and the platform to have the ability to run on Gov AWS.

On this weblog publish, we’re going to take a look at how we constructed the AWS infrastructure wanted for GovSlack and challenges we confronted. When you’re enthusiastic about constructing a brand new service on AWS GovCloud, this publish is for you.

How are GovCloud accounts associated to business accounts?

Not way back, Slack began shifting from a single AWS account to baby accounts. As a part of this undertaking, we additionally made vital modifications to our international community infrastructure. You possibly can learn extra about this within the weblog posts Constructing the Subsequent Evolution of Cloud Networks at Slack and Constructing the Subsequent Evolution of Cloud Networks at Slack – A Retrospective. We have been capable of make the most of most of our learnings into constructing the GovSlack community infrastructure.

To begin with, AWS Gov accounts would not have any billing functionality. The sources within the Gov accounts will propagate their billing right into a linked shell business AWS account. While you request a Gov AWS account, a linked shell business AWS account is mechanically created. Due to this fact the very first thing we needed to do was to request a Gov root AWS account utilizing our root payer business account. This was a prolonged course of, however not as a result of it was a technically troublesome factor to do—it was so simple as clicking a button on our root business AWS account. Nonetheless including the Gov Accounts to our current agreements with AWS did take a couple of weeks. As soon as we had our Gov root account, we have been capable of request extra GovCloud accounts for our service groups. It’s price mentioning that GovCloud baby accounts nonetheless must be requested utilizing the business AWS API utilizing the create-gov-cloud-account name.

When a brand new GovCloud baby account is created, you’ll be able to assume the OrganizationAccountAccessRole within the baby account by way of the GovCloud root account’s OrganizationAccountAccessRole (this function title might differ in case you override the title utilizing –role-name flag).

Let’s take a look at what are these hyperlinks appear like in a diagram:

As we are able to see above, all our GovCloud sources prices are propagated to our root business AWS account.

How did we create GovCloud accounts?

As we mentioned above, we use the AWS organizations API and the create-gov-cloud-account name to request a brand new GovCloud baby account. This course of creates two new accounts: the GovCloud account and the linked business AWS account. We use a pipeline on the business aspect for this portion of the method. Then the linked business AWS account is moved to a extremely restricted OU, so it’s blocked from creating any AWS sources in it.

We use a Jenkins pipeline within the AWS Gov partition to configure the GovCloud baby account. We will assume the OrganizationAccountAccessRole of the brand new baby account from the GovCloud root account as quickly as it’s created. Nonetheless our Gov Jenkins companies are situated in a devoted baby account. Due to this fact there’s a step on this pipeline that can replace the kid account’s OrganizationAccountAccessRole’s belief coverage, so it may be assumed by the Jenkins employees. This step should be accomplished first earlier than we are able to transfer on to different steps of the kid account configuration course of.

How can we separate GovDev and GovProd?

As talked about beforehand, one of many core compliance necessities for a GovCloud setting was that solely US individuals can be approved to the manufacturing setting. With this requirement in thoughts we made the choice to face up two Gov environments, one being the manufacturing Gov setting, recognized internally as “GovProd”, and a second setting, often called “GovDev”. The GovDev setting may be accessed by anybody and check their companies earlier than being deployed to GovProd by US personnel.

To make sure we have now full isolation between these environments, we have now approached the construct out utilizing a full shared-nothing paradigm, which permits the environments to function in fully completely different AWS organizations. The layer 3 networking mesh we use (Nebula) is totally disconnected, that means the networks are solely segregated from each other.

To archive this, we created two AWS organizations in GovCloud, and beneath every of those organizations, an similar set of kid accounts to launch our companies within the Dev and Prod environments.

Is that this actually remoted?

When a brand new baby account is created, we have to use the Gov root account for assuming the OrganizationAccountAccessRole’s into it for the primary portion of the provisioning as we mentioned right here. Since solely US personnel can entry the Gov prod accounts, solely US personnel are capable of entry the Gov root account, as this account has entry to imagine the OrganizationAccountAccessRole within the baby accounts. Due to this fact the preliminary provisioning of dev accounts additionally need to run on Gov prod Jenkins, and US personnel are required to be engaged to kick off the preliminary a part of GovDev accounts creation.

Different challenges

GovProd additionally lacks some AWS companies, reminiscent of CloudFront and public zones in Route53. Moreover, after we are utilizing the AWS CLI in GovCloud, we should go within the –area flag or set the AWS_DEFAULT_REGION setting variable with a Gov area because the AWS CLI at all times defaults to a business area for API calls.

Route53 and ACM

A few of our Gov companies use AWS ACM for the load balancer SSL certifications. We keep away from utilizing e mail certificates validation as this doesn’t enable us to auto-renew expiring certificates. ACM DNS helps auto-renewal however requires public DNS data to take action. Due to this fact, we use the identical devoted business DNS account for validating our ACM certificates as effectively. Entry to this business DNS account is restricted to US personnel.

Route53

AWS GovCloud doesn’t assist public Route53 zones. Nonetheless non-public zones are allowed. We created a GovDev and Gov Prod DNS account for internet hosting non-public Route53 zones. The Cloud Foundations crew creates VPCs in a set of accounts managed by us, then we use AWS Transit gateways to attach completely different areas collectively and construct a worldwide community mesh. Lastly these VPCs are shared into baby accounts to summary the complexity of organising networks from utility groups. You possibly can learn extra about how we do that in our different two weblog posts Constructing the Subsequent Evolution of Cloud Networks at Slack and Constructing the Subsequent Evolution of Cloud Networks at Slack – A Retrospective

The non-public Route53 zones we create are connected to the shared VPCs, in order quickly as a document is added to those zones, it may be resolved inside our VPCs.

Nonetheless since GovCloud doesn’t assist public DNS, we have to create these data on the business aspect. Due to this fact, we created a devoted business AWS account for internet hosting public GovSlack DNS data. Entry to this business DNS account is restricted to US personnel.

How can we switch artefacts between business and GovCloud?

AWS doesn’t assist assuming roles between AWS normal and AWS GovCloud partitions. Due to this fact we created a mechanism to compliantly go objects to GovCloud.

This mechanism ensures the objects are pulled into AWS GovCloud partition from the usual partition utilizing AWS IAM credentials. Credentials to entry the usual partition for pulling these objects are saved securely on the AWS GovCloud partition.

Terraform modules

We use Terraform modules for constructing our infrastructure as a set of interdependent sources reminiscent of VPCs, Web Gateways, Transit Gateways, and route tables. We wished to make use of the identical modules for constructing our Gov infrastructure so we are able to hold these patterns constant between AWS Gov and normal partitions. One key distinction between the business and Gov AWS sources are the sources ARNs. Business ARNs begin with arn:aws versus Gov ARNs begin with arn:aws-us-gov.

Due to this fact we needed to construct a quite simple Terraform module referred to as aws_partition. Utilizing outputs of this module, we are able to programmatically construct ARNs and uncover which AWS partition we’re in.

Let’s take a look at the aws_partition module,

information "aws_caller_identity" "present" 

information "aws_arn" "arn_details" 
  arn = information.aws_caller_identity.present.arn


output "partition" 
  worth = information.aws_arn.arn_details.partition


output "is_govcloud" 
  worth = change(information.aws_arn.arn_details.partition, "gov", "") != information.aws_arn.arn_details.partition ? true : false

Now let’s take a look at a instance utilization,

module "aws_partition" 
  supply = "../modules/aws/aws_partition"


information "aws_iam_policy_document" "instance" 
  assertion 
	impact = "Permit"

	actions = [
	  "s3:GetObject",
	]

	sources = [
	  "arn:$module.aws_partition.partition:iam::*:role/some-role",
	]
  


useful resource "aws_config_config_rule" "instance" 
  rely = module.aws_partition.is_govcloud ? 1 : 0

  title = "example-rule"

  supply 
	proprietor             = "AWS"
	source_identifier = "S3_BUCKET_SERVER_SIDE_ENCRYPTION_ENABLED"
  

VPC endpoints

Over the past three years Slack has been working very arduous to utilize AWS’ VPC endpoints for accessing native AWS companies in our business setting. They cut back the latency and enhance the resiliency of our techniques, whereas additionally lowering our networking prices.

With all these benefits, it’s very straightforward to imagine that it’s a easy transfer, however one obvious subject that we have now present in each the business and GovCloud transfer to VPC endpoints is that AWS doesn’t at all times assist all companies in all AZs. Very often we have now discovered that we have to assist the power for techniques to entry AWS companies each with and with out VPC endpoints, which at instances can create summary edge instances that may be arduous to account for.

Whereas AWS is consistently releasing these VPC endpoints at a AZ stage, we nonetheless haven’t reached 100% of companies enabled for 100% of the areas/AZs we run our service in.

AWS-SSO

Whereas we have been constructing out the Gov setting, we began by utilizing IAM customers to bootstrap the Gov setting, however this was solely ever going to be a short-term answer. AWS lately launched the AWS-SSO answer into their business setting and much more lately of their Gov setting. As this was a whole greenfield buildout it was a very good alternative to experiment with new applied sciences and enhance our current implementation.

Not like AWS’ normal IAM roles, AWS-SSO permission units are an org-wide international (throughout the whole org, versus an account) useful resource, and this modifications how we construct and deploy them.

Since deploying AWS-SSO within the GovCloud setting, we have now taken the learnings and back-ported it into our business setting. Whereas we already had an current SSO system in place for entry to the whole lot of our business AWS setting, utilizing AWS-SSO has made this course of rather a lot smoother and simpler.

So what have we realized?

Rebuilding our total community infrastructure gave us the power to check our tooling, processes,  and Terraform modules, and gave us the chance to make enhancements. We have been capable of clear up a mess of hardcoded values and alter issues to be extra reusable. We have been additionally capable of take a step again and have a deep dive into our processes, instruments, AWS footprint and acquire a larger understanding of our platform as this complete course of gave us a chance to rebuild Slack from scratch.