Deploying to multiple AWS accounts with Terraform?

Deploying to multiple AWS accounts with Terraform? - amazon-web-services

I've been looking for a way to be able to deploy to multiple AWS accounts simultaneously in Terraform and coming up dry. AWS has the concept of doing this with Stacks but I'm not sure if there is a way to do this in Terraform? If so what would be some solutions?
You can read more about the Cloudformation solution here.

You can define multiple provider aliases which can be used to run actions in different regions or even different AWS accounts.
So to perform some actions in your default region (or be prompted for it if not defined in environment variables or ~/.aws/config) and also in US East 1 you'd have something like this:
provider "aws" {
# ...
}
# Cloudfront ACM certs must exist in US-East-1
provider "aws" {
alias = "cloudfront-acm-certs"
region = "us-east-1"
}
You'd then refer to them like so:
data "aws_acm_certificate" "ssl_certificate" {
provider = aws.cloudfront-acm-certs
...
}
resource "aws_cloudfront_distribution" "cloudfront" {
...
viewer_certificate {
acm_certificate_arn = data.aws_acm_certificate.ssl_certificate.arn
...
}
}
So if you want to do things across multiple accounts at the same time then you could assume a role in the other account with something like this:
provider "aws" {
# ...
}
# Assume a role in the DNS account so we can add records in the zone that lives there
provider "aws" {
alias = "dns"
assume_role {
role_arn = "arn:aws:iam::ACCOUNT_ID:role/ROLE_NAME"
session_name = "SESSION_NAME"
external_id = "EXTERNAL_ID"
}
}
And refer to it like so:
data "aws_route53_zone" "selected" {
provider = aws.dns
name = "test.com."
}
resource "aws_route53_record" "www" {
provider = aws.dns
zone_id = data.aws_route53_zone.selected.zone_id
name = "www.${data.aws_route53_zone.selected.name"
...
}
Alternatively you can provide credentials for different AWS accounts in a number of other ways such as hardcoding them in the provider or using different Terraform variables, AWS SDK specific environment variables or by using a configured profile.

I would recommend also combining your solution with Terraform workspaces:
Named workspaces allow conveniently switching between multiple
instances of a single configuration within its single backend. They
are convenient in a number of situations, but cannot solve all
problems.
A common use for multiple workspaces is to create a parallel, distinct
copy of a set of infrastructure in order to test a set of changes
before modifying the main production infrastructure. For example, a
developer working on a complex set of infrastructure changes might
create a new temporary workspace in order to freely experiment with
changes without affecting the default workspace.
Non-default workspaces are often related to feature branches in
version control. The default workspace might correspond to the
"master" or "trunk" branch, which describes the intended state of
production infrastructure. When a feature branch is created to develop
a change, the developer of that feature might create a corresponding
workspace and deploy into it a temporary "copy" of the main
infrastructure so that changes can be tested without affecting the
production infrastructure. Once the change is merged and deployed to
the default workspace, the test infrastructure can be destroyed and
the temporary workspace deleted.
AWS S3 is in the list of the supported backends.
It is very easy to use (similar to working with git branches) and combine it with the selected AWS account.
terraform workspace list
dev
* prod
staging
A few references regarding configuring the AWS provider to work with multiple account:
https://terragrunt.gruntwork.io/docs/features/work-with-multiple-aws-accounts/
https://assets.ctfassets.net/hqu2g0tau160/5Od5r9RbuEYueaeeycUIcK/b5a355e684de0a842d6a3a483a7dc7d3/devopscon-V2.1.pdf

Related

AWS - Creating resources in a multi-account environment

I just created a new AWS account using Terraform aws_organizations_account module. What I am now trying to do is to create ressources into that new account. I guess I would need the account_id of the new AWS account to do that so I stored it into a new output variable but after that I have no idea how can I create a aws_s3_bucket for example
provider.tf
provider "aws" {
region = "us-east-1"
}
main.tf
resource "aws_organizations_account" "account" {
name = "tmp"
email = "first.last+tmp#company.com"
role_name = "myOrganizationRole"
parent_id = "xxxxx"
}
## what I am trying to create inside that tmp account
resource "aws_s3_bucket" "bucket" {}
outputs.tf
output "account_id" {
value = aws_organizations_account.account.id
sensitive = true
}

You can't do this the way you want. You need entire, account creation pipeline for that. Roughly in the pipeline you would have two main stages:
Create your AWS Org and member accounts.
Assume role from the member accounts, and run your TF code for these accounts to create resources.
There are many ways of doing this, and also there are many resources on this topic. Some of them are:
How to Build an AWS Multi-Account Strategy with Centralized Identity Management
Setting up an AWS organization from scratch with Terraform
Terraform on AWS: Multi-Account Setup and Other Advanced Tips
Apart from those, there is also AWS Control Tower, which can be helpful in setting up initial multi-account infrastructure.

How to share AWS infrastructure among multiple accounts using Terraform and AWS SSO?

I have the following multi-account setup with AWS SSO:
An account called "infrastructure-owner". Under this account, there is a role called "SomeAccessLevel" where I can click to sign-in the web console.
Another account called "infrastructure-consumer". Under this account there is the same role called "SomeAccessLevel" where I can click to sign-in the web console. There may be other roles.
Account "infrastructure-owner" owns resources (for example S3 buckets, DynamoDB tables, or VPNs) typically with read/write access. This account is somewhat protected and rarely used. Account "infrastructure-consumer" merely have read access to resources in "infrastructure-owner". This account is used often by multiple people/services. For example, production data pipelines run in "infrastructure-consumer" and have read-only rights to S3 buckets in "infrastructure-owner". However, from time to time, new data may be included manually in these S3 buckets via sign-in "infrastructure-owner".
I would like to provision this infrastructure with Terraform. I am unable to provide permissions for "infrastructure-consumer" to access resources from "infrastructure-owner". I've read dozens of blog posts on AWS multi-account / SSO / Terraform but I still cannot do it. At this point, I cannot even do it manually in the web console.
Please realize that "SomeAccessLevel" is a role created by AWS that I cannot modify (typically called AWSReservedSSO_YOURNAMEHERE_RANDOMSTRING). Also, I cannot give permissions to particular users, since these users may not be owned by "infrastructure-consumer". Also, users access this account via SSO using a role.
The following Terraform code is an example DynamoDB table created in the "infrastructure-owner" that I would like to read in the "infrastructure-consumer" account (any role):
# Terraform config
terraform {
required_version = ">= 1.0.0"
required_providers {
aws = {
source = "hashicorp/aws"
version = "~> 3.44"
}
}
backend "remote" {
hostname = "app.terraform.io"
organization = "YOUR_ORGANIZATION_HERE"
workspaces {
name = "YOUR_TF_WORKSPACE_NAME_HERE" # linked to "infrastructure-owner"
}
}
}
# Local provider
provider "aws" {
profile = "YOUR_AWS_PROFILE_NAME_HERE" # linked to "infrastructure-owner"
region = "eu-central-1"
}
# Example resource that I would like to access from other accounts like "infrastructure-consumer"
resource "aws_dynamodb_table" "my-database" {
# Basic
name = "my-database"
billing_mode = "PAY_PER_REQUEST"
hash_key = "uuid"
# Key
attribute {
name = "uuid"
type = "S"
}
}
# YOUR CODE TO ALLOW "infrastructure-consumer" TO READ THE TABLE.
It could also happen that there is a better architecture for this use case. I am trying to follow general practices for AWS multi-account for production environments, and Terraform for provisioning them.
Thank you!

I assume you mean AWS accounts and not IAM accounts (users).
I remember that roles to be assumed via AWS SSO had something called permission sets, which is no more than a policy with API actions allowed|denied to be performed while assuming a role. I don't know exactly how AWS SSO could influence how role trust works in AWS, but you could have a role in infrastructure-owner's account that trusts anything in infrastructure-consumer's account, i.e. trusting "arn:aws:iam::${var.infrastructure-consumer's account}:root"
To achieve that with Terraform you would run it in your management account (SSO Administrator's Account) and make that trust happen.

How to use multiple AWS account to isolate terraform state between environment

How can I do to use s3 backend that points to a different AWS account?
In other words, I would like to have something like that:
Dev environment state on an S3 bucket in AWS account A
Stage environment state on another S3 bucket on AWS account B
Anyone can help me, please?

The documentation for Terraform's s3 backend includes a section Multi-account AWS Architecture which includes some recommendations, suggestions, and caveats for using Terraform in a multi-account AWS architecture.
That guide is far more detailed than I can reproduce here, but the key points of recommendation are:
Use a separate AWS account for Terraform and any other administrative tools you use to provision and configure your environments, so that the infrastructure that Terraform uses is entirely separate from the infrastructure that Terraform manages.
This reduces the risk of an incorrect Terraform configuration inadvertently breaking your ability to use Terraform itself (e.g. by deleting the state object, or by removing necessary IAM permissions). It also reduces the possibility for an attacker to use vulnerabilities in your main infrastructure to escalate to access to your administrative infrastructure.
Use sts:AssumeRole to indirectly access IAM roles with administrative access in each of your main environment AWS accounts.
This allows you to centralize all of your direct administrative access in a single AWS account where you can more easily audit it, reduces credentials sprawl, and also conveniently configure the AWS provider for that cross-account access (because it has assume_role support built-in).
The guide also discusses using workspaces to represent environments. That advice is perhaps more debatable given the guidance elsewhere in When to use Multiple Workspaces, but the principle of using an administrative account and IAM delegation is still applicable even if you follow this advice of having a separate root module per environment and using shared modules to represent common elements.
As with all things in system architecture, these aren't absolutes and what is best for your case will depend on your details, but hopefully the content in these two documentation sections I've linked to will help you weigh various options and decide what is best for your specific situation.

There are a few solutions to it:
provide aws profile name at the command line while running terraform init and injec terraform backend variables during runtime:
AWS_PROFILE=aws-dev terraform init -backend-config="bucket=825df6bc4eef-state" \
-backend-config="dynamodb_table=825df6bc4eef-state-lock" \
-backend-config="key=terraform-multi-account/terraform.tfstate"
or wrap this command in a Makefile as it is pretty long and forgettable.
Keep separate directories and provide the roles or your credentials or profile name even using shared-credentials
provider "aws" {
region = "us-west-2"
shared_credentials_file = "/Users/tf_user/.aws/creds"
profile = "customprofile"
}
Terraform Workspaces
terragrunt

I don't think it is possible to have a separate S3 backend for each workspace without some hijinks at this time. If you are ok with one S3 backend in one account it's pretty easy to have different accounts associated with each workspace.
# backend.tf
terraform {
backend "s3" {
profile = "default"
bucket = "my-terraform-state"
key = "terraform-multi-account-test/terraform.state"
region = "eu-west-1"
encrypt = true
dynamodb_table = "my-terraform-state-lock"
}
}
and
# provider.tf
variable "workspace_accounts" {
type = map(string)
default = {
"sandbox" = "my-sandbox-keys"
"dev" = "default"
"prod" = "default"
}
}
provider "aws" {
shared_credentials_file = "$HOME/.aws/credentials"
profile = var.workspace_accounts[terraform.workspace]
region = "eu-west-1"
}
See https://github.com/hashicorp/terraform/issues/16627

Terraform Dependancies between accounts [duplicate]

I've been looking for a way to be able to deploy to multiple AWS accounts simultaneously in Terraform and coming up dry. AWS has the concept of doing this with Stacks but I'm not sure if there is a way to do this in Terraform? If so what would be some solutions?
You can read more about the Cloudformation solution here.

You can define multiple provider aliases which can be used to run actions in different regions or even different AWS accounts.
So to perform some actions in your default region (or be prompted for it if not defined in environment variables or ~/.aws/config) and also in US East 1 you'd have something like this:
provider "aws" {
# ...
}
# Cloudfront ACM certs must exist in US-East-1
provider "aws" {
alias = "cloudfront-acm-certs"
region = "us-east-1"
}
You'd then refer to them like so:
data "aws_acm_certificate" "ssl_certificate" {
provider = aws.cloudfront-acm-certs
...
}
resource "aws_cloudfront_distribution" "cloudfront" {
...
viewer_certificate {
acm_certificate_arn = data.aws_acm_certificate.ssl_certificate.arn
...
}
}
So if you want to do things across multiple accounts at the same time then you could assume a role in the other account with something like this:
provider "aws" {
# ...
}
# Assume a role in the DNS account so we can add records in the zone that lives there
provider "aws" {
alias = "dns"
assume_role {
role_arn = "arn:aws:iam::ACCOUNT_ID:role/ROLE_NAME"
session_name = "SESSION_NAME"
external_id = "EXTERNAL_ID"
}
}
And refer to it like so:
data "aws_route53_zone" "selected" {
provider = aws.dns
name = "test.com."
}
resource "aws_route53_record" "www" {
provider = aws.dns
zone_id = data.aws_route53_zone.selected.zone_id
name = "www.${data.aws_route53_zone.selected.name"
...
}
Alternatively you can provide credentials for different AWS accounts in a number of other ways such as hardcoding them in the provider or using different Terraform variables, AWS SDK specific environment variables or by using a configured profile.

How to obtain AWS certificate from different region in terraform? [duplicate]

I've been looking for a way to be able to deploy to multiple AWS accounts simultaneously in Terraform and coming up dry. AWS has the concept of doing this with Stacks but I'm not sure if there is a way to do this in Terraform? If so what would be some solutions?
You can read more about the Cloudformation solution here.

You can define multiple provider aliases which can be used to run actions in different regions or even different AWS accounts.
So to perform some actions in your default region (or be prompted for it if not defined in environment variables or ~/.aws/config) and also in US East 1 you'd have something like this:
provider "aws" {
# ...
}
# Cloudfront ACM certs must exist in US-East-1
provider "aws" {
alias = "cloudfront-acm-certs"
region = "us-east-1"
}
You'd then refer to them like so:
data "aws_acm_certificate" "ssl_certificate" {
provider = aws.cloudfront-acm-certs
...
}
resource "aws_cloudfront_distribution" "cloudfront" {
...
viewer_certificate {
acm_certificate_arn = data.aws_acm_certificate.ssl_certificate.arn
...
}
}
So if you want to do things across multiple accounts at the same time then you could assume a role in the other account with something like this:
provider "aws" {
# ...
}
# Assume a role in the DNS account so we can add records in the zone that lives there
provider "aws" {
alias = "dns"
assume_role {
role_arn = "arn:aws:iam::ACCOUNT_ID:role/ROLE_NAME"
session_name = "SESSION_NAME"
external_id = "EXTERNAL_ID"
}
}
And refer to it like so:
data "aws_route53_zone" "selected" {
provider = aws.dns
name = "test.com."
}
resource "aws_route53_record" "www" {
provider = aws.dns
zone_id = data.aws_route53_zone.selected.zone_id
name = "www.${data.aws_route53_zone.selected.name"
...
}
Alternatively you can provide credentials for different AWS accounts in a number of other ways such as hardcoding them in the provider or using different Terraform variables, AWS SDK specific environment variables or by using a configured profile.

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