New: [AEA-6028] - Added cleanup scripts for old stacks and proxygen instances (#490)

## Summary

- ✨ New Feature

Author: MatthewPopat-NHS

README.md

@@ -2,11 +2,11 @@
 
 ![Build](https://github.com/NHSDigital/eps-cdk-utils/workflows/release/badge.svg?branch=main)
 
-This repository contains a docker image used to deploy CDK to our environments and a CDK constructs library for common EPS project patterns.
+This repository contains a docker image used to deploy CDK to our environments and a CDK constructs library for common EPS project patterns, plus shared deployment utilities.
 
 - `docker/` Contains Dockerfile used to build image used fo for CDK deployments
-- `packages/cdkConstructs/` Contains common CDK constructs used in EPS projects
-- `packages/depoymentUtils/` Contains shared code for standardizing OAS files and performing proxygen deployments
+- `packages/cdkConstructs/` Contains common CDK constructs and CDK helpers used in EPS projects
+- `packages/deploymentUtils/` Contains shared code for standardising OpenAPI specifications and performing Proxygen-based deployments
 - `scripts/` Utilities helpful to developers of this specification
 - `.github/` Contains GitHub workflows that are used for building and deploying from pull requests and releases
 
@@ -17,13 +17,89 @@ The release workflow does the following
  - creates a new version of the cdk construct library and publishes it to github
  - pushes the cdk-utils docker image to dev and all other environments (subject to manual release approval in github actions)
 
-## CDK Constructs
+## CDK Constructs (`packages/cdkConstructs`)
 
-This contains common CDK constructs used in EPS projects.
+This contains common CDK constructs and helpers used in EPS projects.
 
-Available constructs are:
+Available constructs and helpers include:
 
-- `TypescriptLambdaFunction` - A reusable construct for TypeScript Lambda functions
+- `TypescriptLambdaFunction` – A reusable construct for TypeScript Lambda functions
+- `createApp` – Helper for creating a CDK `App` pre-configured with standard EPS tags and stack props
+- `deleteUnusedStacks` – Helper functions for cleaning up superseded or PR-based CloudFormation stacks and their Route 53 records
+
+### CDK app bootstrap (`createApp`)
+
+The helper in [packages/cdkConstructs/src/apps/createApp.ts](packages/cdkConstructs/src/apps/createApp.ts) creates a CDK `App` and applies the standard NHS EPS tagging and configuration.
+
+Usage example:
+
+```ts
+import {createApp} from "@NHSDigital/eps-cdk-constructs"
+
+const {app, props} = createApp({
+	productName: "Electronic Prescription Service",
+	appName: "eps-api",
+	repoName: "eps-cdk-utils",
+	driftDetectionGroup: "eps-api"
+})
+
+// Use `app` and `props` when defining stacks
+```
+
+`createApp` reads deployment metadata from environment variables such as `versionNumber`, `commitId`, `environment` and `isPullRequest`, and exposes them via the returned `props` for use when defining stacks.
+
+### Stack cleanup helpers (`deleteUnusedStacks`)
+
+The helpers in [packages/cdkConstructs/src/stacks/deleteUnusedStacks.ts](packages/cdkConstructs/src/stacks/deleteUnusedStacks.ts) are used to clean up old CloudFormation stacks and their DNS records:
+
+- `deleteUnusedMainStacks(baseStackName, getActiveVersions, hostedZoneName?)` – deletes superseded main and sandbox stacks once the active version has been deployed for at least 24 hours, and removes matching CNAME records from Route 53.
+- `deleteUnusedPrStacks(baseStackName, repoName, hostedZoneName?)` – deletes stacks created for pull requests whose GitHub PRs have been closed, and cleans up their CNAME records.
+
+These functions are designed to be invoked from scheduled jobs (for example, a nightly cleanup workflow) after deployment. They rely on:
+
+- APIM status endpoints to determine the active API versions (via `getActiveApiVersions`).
+- GitHub’s API to determine whether PRs are closed.
+- Route 53 APIs to enumerate and delete CNAME records associated with the stacks.
+
+Refer to [packages/cdkConstructs/tests/stacks/deleteUnusedStacks.test.ts](packages/cdkConstructs/tests/stacks/deleteUnusedStacks.test.ts) for example scenarios.
+
+## Deployment utilities (`packages/deploymentUtils`)
+
+The [packages/deploymentUtils](packages/deploymentUtils) package contains utilities for working with OpenAPI specifications and Proxygen-based API deployments.
+
+It exposes the following main entry points via [packages/deploymentUtils/src/index.ts](packages/deploymentUtils/src/index.ts):
+
+- `deployApi` – Normalises an OpenAPI specification and deploys it via Proxygen Lambda functions, optionally performing blue/green deployments and publishing documentation to the appropriate catalogue.
+- `writeSchemas` – Writes JSON Schemas to disk, collapsing `examples` arrays into a single `example` value to be compatible with OAS.
+- `deleteProxygenDeployments` – Removes Proxygen PTL instances that correspond to closed GitHub pull requests for a given API.
+- Config helpers from `config/index` – used to resolve configuration and CloudFormation export values.
+
+Typical usage pattern (pseudo-code):
+
+```ts
+import {deployApi} from "@NHSDigital/eps-deployment-utils"
+
+await deployApi({
+	spec,
+	apiName: "eps-api",
+	version: "v1.2.3",
+	apigeeEnvironment: "int",
+	isPullRequest: false,
+	awsEnvironment: "dev",
+	stackName: "eps-api-v1-2-3",
+	mtlsSecretName: "eps-api-mtls",
+	clientCertExportName: "ClientCertArn",
+	clientPrivateKeyExportName: "ClientPrivateKeyArn",
+	proxygenPrivateKeyExportName: "ProxygenPrivateKeyArn",
+	proxygenKid: "kid-123",
+	hiddenPaths: ["/internal-only"]
+},
+true,   // blueGreen
+false   // dryRun
+)
+```
+
+See the source files under [packages/deploymentUtils/src/specifications](packages/deploymentUtils/src/specifications) and their tests in [packages/deploymentUtils/tests](packages/deploymentUtils/tests) for fuller examples and expected behaviours.
 
 ## Contributing
 
@@ -49,25 +125,35 @@ See [https://code.visualstudio.com/docs/devcontainers/containers](https://code.v
 All commits must be made using [signed commits](https://docs.github.com/en/authentication/managing-commit-signature-verification/signing-commits).
 
 
-### Testing changes to construct library
-To test changes to the construct library, you need to package the library and install it on the project you want to test it on.
+### Testing changes to construct or deploymentUtils libraries
+To test changes to the construct library or the deploymentUtils package, you need to package the relevant library and install it into the project you want to test it in.
 
 Either 
- - run `make package` from this project and copy the .tgz file from lib folder to the project you want to test in
- - create a pull request and from the pull request workflow run, download nhsdigital-eps-cdk-constructs-1.0.0.tgz to the project you want to test in
+ - run `make package` from this project and copy the generated `.tgz` file(s) from the lib folder to the project you want to test in
+ - create a pull request and from the pull request workflow run, download the generated `.tgz` artifact(s) (for example `nhsdigital-eps-cdk-constructs-1.0.0.tgz` and/or `nhsdigital-eps-deployment-utils-1.0.0.tgz`) to the project you want to test in
 
- In the project you want to test in, run the following
+In the project you want to test in, run the following as appropriate:
 
 ```bash
-npm install --save NHSDigital-eps-cdk-constructs-1.0.0.tgz --workspace packages/cdk/
+# Install the CDK constructs library
+npm install --save nhsdigital-eps-cdk-constructs-1.0.0.tgz --workspace packages/cdk/
+
+# Install the deploymentUtils library
+npm install --save nhsdigital-eps-deployment-utils-1.0.0.tgz --workspace packages/specifications/
 ```
 
-You will then be able to use it - for example:
+You will then be able to use them - for example:
 
 ```typescript
 import {TypescriptLambdaFunction} from "@NHSDigital/eps-cdk-constructs"
 ```
 
+or
+
+```typescript
+import {deployApi} from "@nhsdigital/eps-deployment-utils"
+```
+
 ### Make Commands
 
 There are `make` commands that are run as part of the CI pipeline and help alias some