Provider Default Tags Support

Terratags integrates with AWS provider's default_tags feature. When you define default tags in your AWS provider configuration, Terratags will recognize these tags and consider them when validating resources.

How Default Tags Work

1. Tags defined in the AWS provider's default_tags block are automatically applied to all taggable resources created by that provider
2. Terratags tracks tag inheritance from provider default_tags to individual resources
3. Resources only need to specify tags not covered by default_tags
4. Default tags can be overridden at the resource level if needed

Example with Default Tags

provider "aws" {
  region = "us-west-2"

  default_tags {
    tags = {
      Environment = "dev"
      Owner       = "team-a"
      Project     = "demo"
    }
  }
}

resource "aws_instance" "example" {
  ami           = "ami-12345678"
  instance_type = "t2.micro"

  # Only need to specify Name tag, as other required tags come from default_tags
  tags = {
    Name = "example-instance"
  }
}

In this example, the AWS instance will have all four required tags: Name from the resource-level tags, and Environment, Owner, and Project from the provider's default_tags.

Benefits of Using Default Tags

1. Consistency: Ensures consistent tagging across all resources
2. Reduced Duplication: Eliminates the need to repeat the same tags on every resource
3. Centralized Management: Makes it easier to update tags across all resources
4. Reduced Errors: Minimizes the chance of missing required tags

Default Tags Limitations

1. Provider Specific: Only works with providers that support default_tags (like AWS)
2. Override Behavior: Resource-level tags override default tags with the same key
3. Module Awareness: When using modules, be aware of how default tags propagate

Best Practices

1. Use for Common Tags: Use default_tags for tags that should be consistent across all resources
2. Resource-Specific Tags: Use resource-level tags for tags that are specific to individual resources
3. Documentation: Document which tags are provided by default_tags to avoid confusion
4. Validation: Still use Terratags to validate that all required tags are present