refactor: add middy-like types to commons

Author: dreamorosi

Diff for: packages/commons/src/index.ts

@@ -2,4 +2,5 @@ export * from './utils/lambda';
 export * from './Utility';
 export * from './config';
 export * as ContextExamples from './samples/resources/contexts';
-export * as Events from './samples/resources/events';
+export * as Events from './samples/resources/events';
+export * from './utils/middleware/middy';

Diff for: packages/commons/src/utils/middleware/middy.ts

@@ -0,0 +1,33 @@
+import { Context } from 'aws-lambda';
+
+/**
+ * We need to define these types and interfaces here because we can't import them from @middy/core.
+ * Importing them from @middy/core would introduce a dependency on @middy/core, which we don't want
+ * because we want to keep it as an optional dependency. Those users who don't use the Powertools middleware
+ * and use `tsc` to compile their code will get an error if we import from @middy/core, see #1068.
+ * Given that we use a subset of the @middy/core types, we can define them here and avoid the dependency.
+ */
+interface Request<TEvent = unknown, TResult = unknown, TErr = Error, TContext extends Context = Context> {
+  event: TEvent
+  context: TContext
+  response: TResult | null
+  error: TErr | null
+  internal: {
+    [key: string]: unknown
+  }
+}
+
+declare type MiddlewareFn<TEvent = unknown, TResult = unknown, TErr = Error, TContext extends Context = Context> = (request: Request<TEvent, TResult, TErr, TContext>) => unknown;
+
+export interface MiddlewareLikeObj<TEvent = unknown, TResult = unknown, TErr = Error, TContext extends Context = Context> {
+  before?: MiddlewareFn<TEvent, TResult, TErr, TContext>
+  after?: MiddlewareFn<TEvent, TResult, TErr, TContext>
+  onError?: MiddlewareFn<TEvent, TResult, TErr, TContext>
+}
+
+export interface MiddyLikeRequest {
+  event: unknown
+  context: Context
+  response: unknown | null
+  error: Error | null
+}

Diff for: packages/logger/src/middleware/middy.ts

@@ -1,6 +1,9 @@
 import { Logger } from '../Logger';
-import type middy from '@middy/core';
 import { HandlerOptions, LogAttributes } from '../types';
+import type {
+  MiddlewareLikeObj,
+  MiddyLikeRequest
+} from '@aws-lambda-powertools/commons';
 
 /**
  * A middy middleware that helps emitting CloudWatch EMF metrics in your logs.
@@ -26,12 +29,12 @@ import { HandlerOptions, LogAttributes } from '../types';
  * @param options - (_optional_) Options for the middleware
  * @returns - The middy middleware object
  */
-const injectLambdaContext = (target: Logger | Logger[], options?: HandlerOptions): middy.MiddlewareObj => {
+const injectLambdaContext = (target: Logger | Logger[], options?: HandlerOptions): MiddlewareLikeObj => {
 
   const loggers = target instanceof Array ? target : [target];
   const persistentAttributes: LogAttributes[] = [];
 
-  const injectLambdaContextBefore = async (request: middy.Request): Promise<void> => {
+  const injectLambdaContextBefore = async (request: MiddyLikeRequest): Promise<void> => {
     loggers.forEach((logger: Logger) => {
       if (options && options.clearState === true) {
         persistentAttributes.push({ ...logger.getPersistentLogAttributes() });

Diff for: packages/metrics/src/middleware/middy.ts

@@ -1,6 +1,9 @@
 import type { Metrics } from '../Metrics';
-import type middy from '@middy/core';
 import type { ExtraOptions } from '../types';
+import type {
+  MiddlewareLikeObj,
+  MiddyLikeRequest
+} from '@aws-lambda-powertools/commons';
 
 /**
  * A middy middleware automating capture of metadata and annotations on segments or subsegments for a Lambda Handler.
@@ -29,10 +32,10 @@ import type { ExtraOptions } from '../types';
  * @param options - (_optional_) Options for the middleware
  * @returns middleware - The middy middleware object
  */
-const logMetrics = (target: Metrics | Metrics[], options: ExtraOptions = {}): middy.MiddlewareObj => {
+const logMetrics = (target: Metrics | Metrics[], options: ExtraOptions = {}): MiddlewareLikeObj => {
   const metricsInstances = target instanceof Array ? target : [target];
 
-  const logMetricsBefore = async (request: middy.Request): Promise<void> => {
+  const logMetricsBefore = async (request: MiddyLikeRequest): Promise<void> => {
     metricsInstances.forEach((metrics: Metrics) => {
       metrics.setFunctionName(request.context.functionName);
       const { throwOnEmptyMetrics, defaultDimensions, captureColdStartMetric } = options;

Diff for: packages/tracer/src/middleware/middy.ts

@@ -1,7 +1,10 @@
-import type middy from '@middy/core';
 import type { Tracer } from '../Tracer';
 import type { Segment, Subsegment } from 'aws-xray-sdk-core';
 import type { CaptureLambdaHandlerOptions } from '../types';
+import type {
+  MiddlewareLikeObj,
+  MiddyLikeRequest
+} from '@aws-lambda-powertools/commons';
 
 /**
  * A middy middleware automating capture of metadata and annotations on segments or subsegments for a Lambda Handler.
@@ -30,7 +33,7 @@ import type { CaptureLambdaHandlerOptions } from '../types';
  * @param options - (_optional_) Options for the middleware
  * @returns middleware - The middy middleware object
  */
-const captureLambdaHandler = (target: Tracer, options?: CaptureLambdaHandlerOptions): middy.MiddlewareObj => {
+const captureLambdaHandler = (target: Tracer, options?: CaptureLambdaHandlerOptions): MiddlewareLikeObj => {
   let lambdaSegment: Subsegment | Segment;
 
   const open = (): void => {
@@ -53,7 +56,7 @@ const captureLambdaHandler = (target: Tracer, options?: CaptureLambdaHandlerOpti
     }
   };
 
-  const captureLambdaHandlerAfter = async (request: middy.Request): Promise<void> => {
+  const captureLambdaHandlerAfter = async (request: MiddyLikeRequest): Promise<void> => {
     if (target.isTracingEnabled()) {
       if (options?.captureResponse ?? true) {
         target.addResponseAsMetadata(request.response, process.env._HANDLER);
@@ -62,7 +65,7 @@ const captureLambdaHandler = (target: Tracer, options?: CaptureLambdaHandlerOpti
     }
   };
 
-  const captureLambdaHandlerError = async (request: middy.Request): Promise<void> => {
+  const captureLambdaHandlerError = async (request: MiddyLikeRequest): Promise<void> => {
     if (target.isTracingEnabled()) {
       target.addErrorAsMetadata(request.error as Error);
       close();