The Resource provider Meta-Argument

The provider meta-argument specifies which provider configuration to use for a resource, overriding Terraform's default behavior of selecting one based on the resource type name. Its value should be an unquoted <PROVIDER>.<ALIAS> reference.

As described in Provider Configuration, you can optionally create multiple configurations for a single provider (usually to manage resources in different regions of multi-region services). Each provider can have one default configuration, and any number of alternate configurations that include an extra name segment (or "alias").

By default, Terraform interprets the initial word in the resource type name (separated by underscores) as the local name of a provider, and uses that provider's default configuration. For example, the resource type google_compute_instance is associated automatically with the default configuration for the provider named google.

By using the provider meta-argument, you can select an alternate provider configuration for a resource:

# default configuration
provider "google" {
  region = "us-central1"
}

# alternate configuration, whose alias is "europe"
provider "google" {
  alias  = "europe"
  region = "europe-west1"
}

resource "google_compute_instance" "example" {
  # This "provider" meta-argument selects the google provider
  # configuration whose alias is "europe", rather than the
  # default configuration.
  provider = google.europe

  # ...
}

A resource always has an implicit dependency on its associated provider, to ensure that the provider is fully configured before any resource actions are taken.

The provider meta-argument expects a <PROVIDER>.<ALIAS> reference, which does not need to be quoted. Arbitrary expressions are not permitted for provider because it must be resolved while Terraform is constructing the dependency graph, before it is safe to evaluate expressions.