How would you deploy the same Terraform resource type to multiple AWS regions within a single configuration, using provider aliases?

Declare a second provider "aws" block with an alias (e.g., alias = "us_west"), configured with the different region — then any resource that should use that specific provider instance references it via the provider = aws.us_west meta-argument, while resources without that argument use the default (unaliased) provider configuration. This is how Terraform expresses "multiple configurations of the same provider" within a single configuration.

A provider block without an alias is the default configuration for that provider: resources referencing that provider type (implicitly, by not specifying a provider argument at all) use this default configuration — this is what most single-region configurations rely on without ever needing to think about aliasing.

An aliased provider block is an additional, named configuration of the same provider: provider "aws" { alias = "us_west"; region = "us-west-2" } declares a second, distinctly-named instance of the AWS provider, configured differently (a different region, in this case, though aliasing can also vary credentials/assume-role configuration) — this doesn't replace the default provider, it adds an additional one you can explicitly reference.

Resources opt into a specific provider instance via the provider meta-argument: resource "aws_s3_bucket" "west" { provider = aws.us_west; ... } tells Terraform this specific resource should be created using the aliased provider configuration, not the default one — any resource not specifying this argument uses the default provider as usual.

This pattern extends to modules too, via providers block passing: a module needing to create resources in multiple regions/accounts itself needs to explicitly receive the relevant provider configurations from its caller (via the module's own providers = { aws = aws.us_west, aws.east = aws.us_east } argument at the call site), since providers aren't automatically inherited by child modules the way some other configuration is — this is a deliberate design choice in Terraform requiring explicit provider passing for clarity about which provider configuration a module actually uses.

Common use cases beyond multi-region: the same aliasing mechanism is used for multi-account deployments (an alias configured with a different assume_role), and for any scenario needing more than one configuration of the same provider type within one Terraform run — multi-region is simply the most common, illustrative case.

• A provider block without an alias is the default configuration; an aliased provider block (alias = "...") is an additional, distinctly-named configuration of the same provider type.
• Resources opt into a specific aliased provider via the provider = <type>.<alias> meta-argument; resources without this argument use the default provider.
• Modules don't automatically inherit provider configurations from their caller — they need explicit providers block passing to use a specific aliased provider.
• The same pattern (provider aliasing) is used for multi-account deployments, not just multi-region, wherever more than one configuration of a provider is needed in one run.

• Terraform: Provider Configuration — alias