chore: DeletePolicy should default to retain (#25216)

Considering the still volatile nature of the `import` to Cfn and CDK, the default for the required `DeletePolicy` should be to `Retain`. Any mistake that would create new resources can easily be removed with the stack, but we should not jeopardize existing, possible stateful ones.

[CONTRIBUTING GUIDE]: https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md
[DESIGN GUIDELINES]: https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md

Additional typos corrected.

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: Naumel

packages/aws-cdk/lib/api/cloudformation-deployments.ts

@@ -284,7 +284,7 @@ export interface BuildStackAssetsOptions {
   readonly roleArn?: string;
 
   /**
-   * Options to pass on to `buildAsests()` function
+   * Options to pass on to `buildAssets()` function
    */
   readonly buildOptions?: BuildAssetsOptions;
 }

packages/aws-cdk/lib/cdk-toolkit.ts

@@ -239,7 +239,7 @@ export class CdkToolkit {
               'but terminal (TTY) is not attached so we are unable to get a confirmation from the user');
           }
 
-          // only talk to user if concurreny is 1 (otherwise, fail)
+          // only talk to user if concurrency is 1 (otherwise, fail)
           if (concurrency > 1) {
             throw new Error(
               '"--require-approval" is enabled and stack includes security-sensitive updates, ' +
@@ -570,7 +570,7 @@ export class CdkToolkit {
    * Synthesize the given set of stacks (called when the user runs 'cdk synth')
    *
    * INPUT: Stack names can be supplied using a glob filter. If no stacks are
-   * given, all stacks from the application are implictly selected.
+   * given, all stacks from the application are implicitly selected.
    *
    * OUTPUT: If more than one stack ends up being selected, an output directory
    * should be supplied, where the templates will be written.
@@ -1159,7 +1159,7 @@ function roundPercentage(num: number): number {
 }
 
 /**
- * Given a time in miliseconds, return an equivalent amount in seconds.
+ * Given a time in milliseconds, return an equivalent amount in seconds.
  */
 function millisecondsToSeconds(num: number): number {
   return num / 1000;

packages/aws-cdk/lib/cli.ts

@@ -485,7 +485,7 @@ export async function exec(args: string[], synthesizer?: Synthesizer): Promise<n
         });
 
       case 'bootstrap':
-        const source: BootstrapSource = determineBootsrapVersion(args, configuration);
+        const source: BootstrapSource = determineBootstrapVersion(args, configuration);
 
         const bootstrapper = new Bootstrapper(source);
 
@@ -663,7 +663,7 @@ export async function exec(args: string[], synthesizer?: Synthesizer): Promise<n
  * Determine which version of bootstrapping
  * (legacy, or "new") should be used.
  */
-function determineBootsrapVersion(args: { template?: string }, configuration: Configuration): BootstrapSource {
+function determineBootstrapVersion(args: { template?: string }, configuration: Configuration): BootstrapSource {
   const isV1 = version.DISPLAY_VERSION.startsWith('1.');
   return isV1 ? determineV1BootstrapSource(args, configuration) : determineV2BootstrapSource(args);
 }

packages/aws-cdk/lib/import.ts

@@ -145,7 +145,7 @@ export class ResourceImporter {
   }
 
   /**
-   * Perform a diff between the currently running and the new template, enusre that it is valid
+   * Perform a diff between the currently running and the new template, ensure that it is valid
    * for importing and return a list of resources that are being added in the new version
    *
    * @return mapping logicalResourceId -> resourceDifference
@@ -171,7 +171,7 @@ export class ResourceImporter {
         warning(`Ignoring updated/deleted resources (--force): ${offendingResources.join(', ')}`);
       } else {
         throw new Error('No resource updates or deletes are allowed on import operation. Make sure to resolve pending changes ' +
-                        `to existing resources, before attempting an import. Updated/deleted resources: ${offendingResources.join(', ')} (--force to override)`);
+          `to existing resources, before attempting an import. Updated/deleted resources: ${offendingResources.join(', ')} (--force to override)`);
       }
     }
 
@@ -199,7 +199,7 @@ export class ResourceImporter {
   }
 
   /**
-   * Return teh current template, with the given resources added to it
+   * Return the current template, with the given resources added to it
    */
   private async currentTemplateWithAdditions(additions: ImportableResource[]): Promise<any> {
     const template = await this.currentTemplate();
@@ -397,14 +397,16 @@ function fmtdict<A>(xs: Record<string, A>) {
 }
 
 /**
- * Add a default 'Delete' policy, which is required to make the import succeed
+ * Add a default `DeletionPolicy` policy.
+ * The default value is set to 'Retain', to lower risk of unintentionally
+ * deleting stateful resources in the process of importing to CDK.
  */
 function addDefaultDeletionPolicy(resource: any): any {
   if (resource.DeletionPolicy) { return resource; }
 
   return {
     ...resource,
-    DeletionPolicy: 'Delete',
+    DeletionPolicy: 'Retain',
   };
 }