Merge pull request #92 from guardian/aa-param-helper

feat: add parameter helper functions on GuStack

src/constructs/core/parameters.test.ts

@@ -1,22 +1,17 @@
 import "@aws-cdk/assert/jest";
 import { SynthUtils } from "@aws-cdk/assert/lib/synth-utils";
-import { Stack } from "@aws-cdk/core";
 import { simpleGuStackForTesting } from "../../../test/utils";
 import type { SynthedStack } from "../../../test/utils";
-import { Stage, Stages } from "../../constants";
 import {
   GuAmiParameter,
   GuArnParameter,
   GuInstanceTypeParameter,
   GuParameter,
   GuS3ObjectArnParameter,
-  GuStackParameter,
-  GuStageParameter,
   GuStringParameter,
   GuSubnetListParameter,
   GuVpcParameter,
 } from "./parameters";
-import type { GuStack } from "./stack";
 
 describe("The GuParameter class", () => {
   it("sets the type as passed through by default", () => {
@@ -84,39 +79,6 @@ describe("The GuStringParameter class", () => {
   });
 });
 
-describe("The GuStageParameter class", () => {
-  it("should set the values as required", () => {
-    const stack = new Stack() as GuStack;
-
-    new GuStageParameter(stack);
-
-    const json = SynthUtils.toCloudFormation(stack) as SynthedStack;
-
-    expect(json.Parameters.Stage).toEqual({
-      Type: "String",
-      Description: "Stage name",
-      AllowedValues: Stages,
-      Default: Stage.CODE,
-    });
-  });
-});
-
-describe("The GuStackParameter class", () => {
-  it("should set the values as required", () => {
-    const stack = new Stack() as GuStack;
-
-    new GuStackParameter(stack);
-
-    const json = SynthUtils.toCloudFormation(stack) as SynthedStack;
-
-    expect(json.Parameters.Stack).toEqual({
-      Type: "String",
-      Description: "Name of this stack",
-      Default: "deploy",
-    });
-  });
-});
-
 describe("The GuInstanceTypeParameter class", () => {
   it("should combine default, override and prop values", () => {
     const stack = simpleGuStackForTesting();

src/constructs/core/parameters.ts

@@ -10,11 +10,16 @@ export interface GuParameterProps extends CfnParameterProps {
 export type GuNoTypeParameterProps = Omit<GuParameterProps, "type">;
 
 export class GuParameter extends CfnParameter {
+  public readonly id: string;
+
   constructor(scope: GuStack, id: string, props: GuParameterProps) {
     super(scope, id, {
       ...props,
       type: props.fromSSM ? `AWS::SSM::Parameter::Value<${props.type ?? "String"}>` : props.type,
     });
+
+    this.id = id;
+    scope.setParam(this);
   }
 }
 
@@ -25,7 +30,8 @@ export class GuStringParameter extends GuParameter {
 }
 
 export class GuStageParameter extends GuParameter {
-  constructor(scope: GuStack, id: string = "Stage") {
+  public static readonly defaultId = "Stage";
+  constructor(scope: GuStack, id: string = GuStageParameter.defaultId) {
     super(scope, id, {
       type: "String",
       description: "Stage name",
@@ -36,7 +42,8 @@ export class GuStageParameter extends GuParameter {
 }
 
 export class GuStackParameter extends GuParameter {
-  constructor(scope: GuStack, id: string = "Stack") {
+  public static readonly defaultId = "Stack";
+  constructor(scope: GuStack, id: string = GuStackParameter.defaultId) {
     super(scope, id, {
       type: "String",
       description: "Name of this stack",

src/constructs/core/stack.test.ts

@@ -7,6 +7,7 @@ import { alphabeticalTags, simpleGuStackForTesting } from "../../../test/utils";
 import type { SynthedStack } from "../../../test/utils";
 import { Stage, Stages } from "../../constants";
 import { TrackingTag } from "../../constants/library-info";
+import { GuParameter } from "./parameters";
 import { GuStack } from "./stack";
 
 describe("The GuStack construct", () => {
@@ -63,4 +64,21 @@ describe("The GuStack construct", () => {
 
     expect(stack.app).toBe("MyApp");
   });
+
+  it("should return a parameter that exists", () => {
+    const stack = new GuStack(new App(), "Test", { app: "MyApp", stack: "test" });
+    const testParam = new GuParameter(stack, "MyTestParam", {});
+    stack.setParam(testParam);
+
+    const actual = stack.getParam<GuParameter>("MyTestParam");
+    expect(actual).toBe(testParam);
+  });
+
+  it("should throw on attempt to get a parameter that doesn't exist", () => {
+    const stack = new GuStack(new App(), "Test", { app: "MyApp", stack: "test" });
+
+    expect(() => stack.getParam<GuParameter>("i-do-not-exist")).toThrowError(
+      "Attempting to read parameter i-do-not-exist which does not exist"
+    );
+  });
 });

src/constructs/core/stack.ts

@@ -1,6 +1,7 @@
 import type { App, StackProps } from "@aws-cdk/core";
 import { Stack, Tags } from "@aws-cdk/core";
 import { TrackingTag } from "../../constants/library-info";
+import type { GuParameter } from "./parameters";
 import { GuStageParameter } from "./parameters";
 
 export interface GuStackProps extends StackProps {
@@ -39,14 +40,15 @@ export interface GuStackProps extends StackProps {
  * ```
  */
 export class GuStack extends Stack {
-  private readonly _stage: GuStageParameter;
   private readonly _stack: string;
   private readonly _app: string;
 
+  private params: Map<string, GuParameter>;
+
   public readonly migratedFromCloudFormation: boolean;
 
   get stage(): string {
-    return this._stage.valueAsString;
+    return this.getParam(GuStageParameter.defaultId).valueAsString;
   }
 
   get stack(): string {
@@ -73,13 +75,27 @@ export class GuStack extends Stack {
     Tags.of(this).add(key, value, { applyToLaunchedInstances });
   }
 
+  setParam(value: GuParameter): void {
+    this.params.set(value.id, value);
+  }
+
+  getParam<T extends GuParameter>(key: string): T {
+    if (!this.params.has(key)) {
+      throw new Error(`Attempting to read parameter ${key} which does not exist`);
+    }
+
+    return this.params.get(key) as T;
+  }
+
   // eslint-disable-next-line custom-rules/valid-constructors -- GuStack is the exception as it must take an App
   constructor(app: App, id: string, props: GuStackProps) {
     super(app, id, props);
 
     this.migratedFromCloudFormation = !!props.migratedFromCloudFormation;
 
-    this._stage = new GuStageParameter(this);
+    this.params = new Map<string, GuParameter>();
+
+    new GuStageParameter(this);
     this._stack = props.stack;
     this._app = props.app;