# Videos ## AWS re:Invent 2019: \[REPEAT 1] Best practices for authoring AWS CloudFormation (DOP302-R1) {% embed url="" %} ### Authoring Best Practices * Parameters: Avoid hardcoding values, can add validation to users and improve UX with console grouping, labels, descriptions; keep secrets in SSM Parameter Store and Secrets Manager * Mappings: As a case statement, helps maintain a set of information for various environments * Conditions: Simple if/then statements (e.g. if dev do this, if prod do that) * Imports and exports, leverage cross-stack references or export/import values through SSM * Use !Sub over !Join * Leverage SSM Parameter Store for latest AMI instance IDs ### Testing & Deployment Best Practices * Run Lint in headless mode, prevent promoting templates with errors * Use [TaskCat](https://github.com/aws-quickstart/taskcat/tree/master/taskcat) to live-test infrastructure * Use ChangeSets to know what effect the change will have on the underlying resources before actually deploying it * Use StackSets to deploy across multiple accounts and regions * Use automated deployment pipelines to deploy infrastructure changes * Refactor large stacks with resource import * Detect and remediate drift ### StackSets best practices * Partially deploy your CloudFormation StackSet updates to reduce blast radius; great for sanity testing / releasing incrementally * Depending on your speed needs, consider setting a higher concurrent account limit * Use parameter overrides to define specific parameters in account-region pairs * Separate stacks by function and frequency of changes needed --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://notebook.iuriioapps.com/cloud/aws/automation-and-optimization/cloudformation/videos.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.