Validate your templates with sam validate. Currently, this command validates that the template provided is valid JSON / YAML. As with most AWS SAM CLI commands, it looks for a template.[yaml|yml] file in your current working directory by default. You can specify a different template file/location with the -t or --template option.
Example:
sam validate
<path-to-file>/template.yml is a valid SAM Template
Note
The sam validate command requires AWS credentials to be configured. For more information, see Configuration and Credential Files.