CloudFormation template errors.

AWS CloudFormation allows you to define and provision AWS infrastructure as code. When working with CloudFormation templates, you may encounter various errors. Here are some common CloudFormation template errors and potential solutions:

1. Syntax Errors:
   • Cause: Invalid JSON or YAML syntax in the template.
   • Solution: Use a JSON or YAML validator to identify and correct syntax errors. Ensure that all brackets, commas, colons, etc., are properly formatted.
2. Resource Name Conflicts:
   • Cause: Resource names must be unique within a CloudFormation stack.
   • Solution: Ensure that all resource names, such as AWS::EC2::Instance or AWS::S3::Bucket, are unique within the template.
3. Missing Required Properties:
   • Cause: Some resources have required properties that are not specified in the template.
   • Solution: Refer to the AWS documentation for the specific resource type and ensure that all required properties are included.
4. Invalid Resource Type:
   • Cause: A resource type specified in the template is not a valid AWS resource type.
   • Solution: Check the AWS documentation for valid resource types and ensure you are using the correct type.
5. Invalid Parameter or Output References:
   • Cause: Referencing a parameter or output that doesn't exist in the template.
   • Solution: Double-check the spelling and capitalization of parameter and output names to ensure they match the template.
6. Circular Dependencies:
   • Cause: Resources have circular dependencies, which CloudFormation cannot resolve.
   • Solution: Review the dependencies between resources and restructure the template to eliminate circular references.
7. Invalid Intrinsic Functions:
   • Cause: Incorrect use of intrinsic functions like Fn::Ref, Fn::ImportValue, or Fn::Sub.
   • Solution: Check the AWS documentation for the correct usage of intrinsic functions and ensure they are used appropriately.
8. Invalid Condition Usage:
   • Cause: Conditions must be evaluated to be either true or false, and they may not be used in certain contexts.
   • Solution: Verify that conditions are used appropriately, and consider using conditions only where allowed.
9. Template Size Exceeds Limits:
   • Cause: The CloudFormation template size exceeds the maximum allowed size.
   • Solution: If your template is too large, consider breaking it into smaller templates or using nested stacks.
10. Incorrect IAM Permissions:
    • Cause: The IAM user or role executing the CloudFormation stack creation/update does not have the necessary permissions.
    • Solution: Ensure that the IAM user or role has the required permissions to create/update the resources specified in the template.
11. Invalid Parameter Values:
    • Cause: Providing parameter values that do not meet the specified constraints or type requirements.
    • Solution: Review the parameter definitions and ensure that the values provided align with the specified constraints.
12. Resource Deletion Policy Conflicts:
    • Cause: Conflicting deletion policies defined for a resource.
    • Solution: Review deletion policies (e.g., Retain, Delete, Snapshot) for resources and ensure they are set appropriately.
13. Template References Nonexistent Resources:
    • Cause: The template references resources that do not exist in the stack.
    • Solution: Double-check resource names and ensure they match the actual resources in the stack.

For more complex issues or specific error messages, consulting the AWS CloudFormation documentation and forums can provide additional guidance. Additionally, using tools like AWS CloudFormation Designer or AWS CloudFormation Linter can help identify and rectify errors in your templates.