feat: config utility

README.md

@@ -1,6 +1,6 @@
 # cdk-practical-constructs
 
-A collection of CDK constructs for making the development of AWS based applications easier and safer in a practical way.
+A collection of CDK constructs and utilities for making the development of AWS based applications easier and safer in a practical way.
 
 See examples for BaseNodeJsLambda and OpenApiGatewayLambda below.
 

package.json

@@ -40,6 +40,7 @@
     "fs": "0.0.1-security",
     "npm-which": "^3.0.1",
     "openapi3-ts": "^4.2.1",
+    "scoperjs": "^1.0.0",
     "tmp": "^0.2.1",
     "zod": "^3.22.4"
   },

src/config/configs.test.ts

@@ -0,0 +1,58 @@
+/* eslint-disable camelcase */
+import { RetentionDays } from 'aws-cdk-lib/aws-logs';
+
+import { LambdaConfig } from '..';
+
+import { StageConfig, StagesConfig, resolveStageConfig } from './configs';
+
+type TestConfig = StageConfig & {
+  lambda: LambdaConfig;
+};
+
+const testStageConfigs: StagesConfig<TestConfig> = {
+  default: {
+    lambda: {
+      allowAllOutbound: true,
+      logRetention: RetentionDays.ONE_WEEK,
+    },
+  },
+  dev: {
+    lambda: {
+      logRetention: RetentionDays.ONE_DAY,
+      bundling: {
+        sourceMap: true,
+      },
+    },
+  },
+  prd: {
+    lambda: {
+      logRetention: RetentionDays.SIX_MONTHS,
+    },
+  },
+};
+
+describe('configs', () => {
+  it('resolve config with dev overrides', async () => {
+    const stageConfig = resolveStageConfig<TestConfig>('dev', testStageConfigs);
+    expect(stageConfig.lambda.allowAllOutbound).toBeTruthy();
+    expect(stageConfig.lambda.logRetention).toBe(RetentionDays.ONE_DAY);
+  });
+
+  it('resolve stage "dev-pr-123" with same contents as stage "dev"', async () => {
+    const stageConfig = resolveStageConfig<TestConfig>('dev-pr-123', testStageConfigs);
+    expect(stageConfig.lambda.allowAllOutbound).toBeTruthy();
+    expect(stageConfig.lambda.logRetention).toBe(RetentionDays.ONE_DAY);
+  });
+
+  it('resolve prd config with defaults', async () => {
+    const stageConfig = resolveStageConfig<TestConfig>('tst', testStageConfigs);
+    expect(stageConfig.lambda.allowAllOutbound).toBeTruthy();
+    expect(stageConfig.lambda.logRetention).toBe(RetentionDays.ONE_WEEK);
+  });
+
+  it('resolve acc config with defaults', async () => {
+    const stageConfig = resolveStageConfig<TestConfig>('prd', testStageConfigs);
+    expect(stageConfig.lambda.allowAllOutbound).toBeTruthy();
+    expect(stageConfig.lambda.logRetention).toBe(RetentionDays.SIX_MONTHS);
+  });
+});

src/config/configs.ts

@@ -0,0 +1,46 @@
+import { Scoper } from 'scoperjs';
+
+// https://stackoverflow.com/questions/43159887/make-a-single-property-optional-in-typescript
+export type PartialBy<T, K extends keyof T> = Omit<T, K> & Partial<Pick<T, K>>;
+
+export type StagesConfig<T extends StageConfig> = {
+  default: T;
+  [stage: string]: T;
+};
+
+export type StageConfig = {
+  stage?: string;
+};
+
+/**
+ * Returns the prefix for a stage name identified by a '-'. e.g: for 'dev-pr-123', it returns 'dev'
+ * @param stageName Full stage name. e.g: dev-pr-123, dev-testing-deploy, acc-frozen
+ * @returns Prefix of stage name. e.g: 'dev'
+ */
+export const getStagePrefix = (stage: string): string => {
+  return stage.replaceAll(/-.*/g, '');
+};
+
+/**
+ * Resolves a stage configuration by merging global configs with specific stage configs
+ * @param {string} stage such as 'dev', 'tst', 'acc', 'prd', 'dev-pr-123'. The actual stage name for getting the config will be the stage name prefixed by "-" if exists. For example, for 'dev-pr-123', it will be used 'dev'
+ * @param {StagesConfig<T>} stagesConfig Configuration for all stages along with default values if the stage doesn't define a specific value
+ * @returns {StageConfig}
+ */
+export function resolveStageConfig<T extends StageConfig>(
+  stage: string,
+  stagesConfig: StagesConfig<T>,
+): T {
+  const contexter = Scoper.create<T>(stagesConfig.default);
+  // eslint-disable-next-line no-restricted-syntax
+  for (const [stagek, config] of Object.entries(stagesConfig)) {
+    contexter.setScopeValue(stagek, config);
+  }
+
+  // get stage context by stage prefix name. e.g: context 'dev' when stage is 'dev-pr-123'
+  const stagePrefix = getStagePrefix(stage);
+
+  const stageValue = contexter.getValue(stagePrefix);
+  stageValue.stage = stage;
+  return stageValue;
+}