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Metadata and tags serve different purposes in AWS CloudFormation templates:
  • Metadata is free-form, machine-readable information you can attach to a template or a resource for documentation, tooling, or processing.
  • Tags are key/value labels attached to supported resources at provisioning time to help with organization, automation, cost allocation, and policy enforcement.
This page shows concise examples of both approaches, explains where to place each in a YAML template, and walks through updating a stack so tags appear on the created resources.

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Resource-level Metadata example

Place Metadata under a specific resource to annotate that resource only: 
Resources:
  MyS3Bucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: eden-kodekloud-xcvt-bkt
    Metadata:
      Purpose: "Creating an s3 bucket"
      Reviewed: "02-07-2025"

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Template-level Metadata example

For template-wide annotations, use the top-level Metadata section (not nested under Resources): 
Resources:
  MyS3Bucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: eden-kodekloud-xcvt-bkt

Metadata:
  Purpose: "Creating an s3 bucket"
  Reviewed: "02-07-2025"
  Owner: "John Doe"
  Contact: "johndoe@mail.com"

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Adding Tags to a resource

Tags must be declared under a resource’s Properties as a YAML list of Key/Value pairs. Make sure Tags aligns with other properties. Example — S3 bucket with tags: 
Resources:
  MyS3Bucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: eden-kodekloud-xcvt-bkt
      Tags:
        - Key: Developer
          Value: "Arno Pretorius"
        - Key: Environment
          Value: "Development"
Best practices and notes:
  • Use Key and Value with the exact casing (Key: and Value:) as shown.
  • You can include intrinsic functions (e.g., !Ref, !Sub) inside tag values for dynamic content.
  • Save your template file before uploading it in the CloudFormation console or using the CLI.

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Quick comparison: Metadata vs Tags

FeatureMetadataTags
PurposeDocumentation, tooling, machine-readable annotationsResource classification, cost allocation, policy enforcement
PlacementResource-level or top-level MetadataUnder Properties as Tags list
Visible in service consolesNo (template-only unless used by tooling)Yes — visible in resource consoles (S3, EC2, etc.)
Supports CloudFormation propagationNoYes — CloudFormation adds tags during provisioning for supported resources

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Update a stack to apply template changes (CloudFormation console)

  1. In the AWS CloudFormation console, choose the stack you want to update and select Update.
  2. Choose Replace current template → Upload a template file, then select your saved YAML file and continue through the wizard.
  3. In the Configure stack options step you can add or edit tags directly in the console before submitting the update.
A browser screenshot of the AWS CloudFormation console on the "Configure stack options" step for a stack named DemoStack. The page shows the Tags (optional) section with an "Add new tag" button and the left-hand step progress navigation.
After submitting the update, CloudFormation will apply the changes. Monitor stack events and status in the console until the update completes.

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Verify tags on the S3 bucket

  1. Open the Amazon S3 console and locate the bucket created by the stack (example: eden-kodekloud-xcvt-bkt).
  2. Open the bucket and view the Tags section in the Properties tab to confirm tags defined in the template are present.
A screenshot of the AWS S3 console showing the Tags panel for the bucket "eden-kodekloud-xcvt-bkt", listing tag keys and values such as aws:cloudformation:stack-name = DemoStack and Environment = Development. The page shows an Edit button and the CloudShell/footer bar at the bottom.
You might also see additional CloudFormation-generated tags such as:
  • aws:cloudformation:stack-name
  • aws:cloudformation:logical-id
  • aws:cloudformation:stack-id
CloudFormation automatically attaches stack-identifying tags (such as aws:cloudformation:stack-name, aws:cloudformation:logical-id, and aws:cloudformation:stack-id) to supported resources when the stack is created or updated. This is expected behavior and helps with resource tracking and cost allocation.

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Practical tips

  • If you want consistent tags across all resources in a stack, consider adding tags in the CloudFormation console during stack creation/update or use a stack-level tagging strategy supported by some resource types.
  • To programmatically validate tags after deployment, use the AWS CLI or SDKs (for example, aws s3api get-bucket-tagging for S3).
  • Remember that some services may not support tag propagation from CloudFormation; check the resource documentation.

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Summary

  • Use Metadata for descriptive, template- or resource-level machine-readable notes.
  • Use Tags under Properties to label resources for organization, automation, and cost allocation.
  • Save and upload your template when updating a stack and verify tags in the target service console after the update completes.

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