Terraform — Multiple Providers

Companion lab for the Medium article Terraform — Using Multiple Providers. Part of my Terraform fundamentals series — more on Medium.

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What you'll learn

How to deploy resources to multiple AWS regions (or multiple AWS accounts) from a single Terraform project using provider aliases — the canonical pattern for cross-region and multi-account infrastructure.

Architecture

┌──────────────────┐       ┌──────────────────────────────────┐
│   Terraform      │       │   AWS                            │
│                  │       │                                  │
│   provider.aws   │ ────► │   S3 bucket · us-east-1 (VA)     │
│                  │       │                                  │
│   provider.aws   │ ────► │   S3 bucket · eu-west-3 (Paris)  │
│   .paris (alias) │       │                                  │
└──────────────────┘       └──────────────────────────────────┘

One codebase, two provider instances, two regions.

What's inside

File	Purpose
provider.tf	Declares two AWS provider instances: default (us-east-1) and paris alias (eu-west-3)
variables.tf	Defines bucket_virginia and bucket_paris input variables
main.tf	Creates S3 buckets — one in each region, using provider = aws.paris on the second
output.tf	Outputs the regional domain names of both buckets
backend.tf	Configures local state backend

Prerequisites

• Terraform ≥ 1.5
• AWS CLI configured (aws configure) with a default profile that has access to both regions
• Globally unique S3 bucket names — set bucket_virginia and bucket_paris via terraform.tfvars or -var (the defaults will collide)

Quick start

# Initialize (downloads the AWS provider once, used for both aliases)
terraform init

# Preview — you should see 2 S3 buckets, one per region
terraform plan \
  -var="bucket_virginia=my-unique-va-bucket-2026" \
  -var="bucket_paris=my-unique-paris-bucket-2026"

# Apply
terraform apply \
  -var="bucket_virginia=my-unique-va-bucket-2026" \
  -var="bucket_paris=my-unique-paris-bucket-2026"

# Inspect the outputs
terraform output

Expected output: two s3.<region>.amazonaws.com domain names, one for Virginia and one for Paris.

Cleanup

terraform destroy \
  -var="bucket_virginia=my-unique-va-bucket-2026" \
  -var="bucket_paris=my-unique-paris-bucket-2026"

Key concepts

• Provider aliases — alias = "paris" creates a second provider instance you can reference as aws.paris
• provider = resource argument — attach a resource to a specific provider instance (provider = aws.paris)
• Single terraform init — downloads the provider plugin once even for multiple instances
• Multi-region (and by extension, multi-account) pattern — swap regions for account credentials to manage infra across AWS accounts

When you'd use this in production

• Cross-region DR — primary in us-east-1, disaster recovery in another region
• Multi-account organization — one Terraform root module managing infra across accounts via assume-role
• Mixing cloud providers — provider.aws + provider.gcp + provider.azurerm all in one module

Series

Part of my Terraform fundamentals series:

• Previous: Managing Environments with Terraform Workspaces
• Also in series: Creating Your First Instance with Terraform

All articles on Medium.