Merge pull request #623 from govuk-one-login/OJ-3220

OJ-3220 - Handle ResourceAlreadyExistsException in PIIRedactFunction createLogStream()

Author: barnabycollins

lambdas/pii-redact/src/pii-redact-handler.ts

@@ -8,6 +8,7 @@ import {
   PutLogEventsCommand,
   PutLogEventsCommandOutput,
   CreateLogStreamCommand,
+  ResourceAlreadyExistsException,
 } from "@aws-sdk/client-cloudwatch-logs";
 import { redactPII } from "./pii-redactor";
 import {
@@ -19,24 +20,22 @@ import { initOpenTelemetry } from "../../open-telemetry/src/otel-setup";
 
 initOpenTelemetry();
 
-const logger = new Logger();
 const cloudwatch = new CloudWatchLogsClient();
 
 const logStreamTrackingTable = process.env.RedactionLogStreamTrackingTable;
 
 export class PiiRedactHandler implements LambdaInterface {
-  private readonly dynamodb: DynamoDBClient;
-
-  constructor(dynamodb = new DynamoDBClient()) {
-    this.dynamodb = dynamodb;
-  }
+  constructor(
+    private readonly dynamodb = new DynamoDBClient(),
+    private readonly logger = new Logger()
+  ) {}
 
   public async handler(
     event: CloudWatchLogsEvent,
     _context: unknown
   ): Promise<object> {
     try {
-      logger.info("Received " + JSON.stringify(event));
+      this.logger.info("Received " + JSON.stringify(event));
 
       const logDataBase64 = event.awslogs.data;
       const logDataBuffer = Buffer.from(logDataBase64, "base64");
@@ -56,7 +55,7 @@ export class PiiRedactHandler implements LambdaInterface {
       return {};
     } catch (error: unknown) {
       const message = error instanceof Error ? error.message : String(error);
-      logger.error(`Error in PiiRedactHandler: ${message}`);
+      this.logger.error(`Error in PiiRedactHandler: ${message}`);
       throw error;
     }
   }
@@ -66,7 +65,7 @@ export class PiiRedactHandler implements LambdaInterface {
     logStream: string,
     logEvents: CloudWatchLogsDecodedData
   ) {
-    logger.info("Putting redacted logs into " + redactLogGroup);
+    this.logger.info("Putting redacted logs into " + redactLogGroup);
 
     try {
       const response: PutLogEventsCommandOutput = await cloudwatch.send(
@@ -81,26 +80,38 @@ export class PiiRedactHandler implements LambdaInterface {
           })),
         })
       );
-      logger.info(JSON.stringify(response));
+      this.logger.info(JSON.stringify(response));
     } catch (error) {
-      logger.error(`Error putting log events into ${redactLogGroup}: ${error}`);
+      this.logger.error(
+        `Error putting log events into ${redactLogGroup}: ${error}`
+      );
       throw error;
     }
   }
 
   private async createLogStream(logStreamName: string, logGroupName: string) {
     if (!(await this.logStreamExists(logStreamName))) {
-      logger.info("Creating log stream " + logStreamName);
-
-      await cloudwatch.send(
-        new CreateLogStreamCommand({
-          logGroupName: logGroupName,
-          logStreamName: logStreamName,
-        })
-      );
+      this.logger.info("Creating log stream " + logStreamName);
+
+      try {
+        await cloudwatch.send(
+          new CreateLogStreamCommand({
+            logStreamName: logStreamName,
+            logGroupName: logGroupName,
+          })
+        );
+      } catch (error: unknown) {
+        if (error instanceof ResourceAlreadyExistsException) {
+          this.logger.info(logStreamName + " already exists");
+        } else {
+          throw error;
+        }
+      }
 
       await this.saveLogStreamRecordInDB(logStreamName);
-      logger.info("Added " + logStreamName + " to " + logStreamTrackingTable);
+      this.logger.info(
+        "Added " + logStreamName + " to " + logStreamTrackingTable
+      );
     }
   }
 

lambdas/pii-redact/tests/pii-redact-handler.test.ts

@@ -2,21 +2,31 @@ import { PiiRedactHandler } from "../src/pii-redact-handler";
 import * as zlib from "node:zlib";
 import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
 import mocked = jest.mocked;
+import { ResourceAlreadyExistsException } from "@aws-sdk/client-cloudwatch-logs";
+import { mockLogger } from "./utils";
 
-let shouldMockThrowError = false;
+let throwMockError: null | "Error" | "ResourceAlreadyExistsException" = null;
 
 jest.mock("@aws-sdk/client-cloudwatch-logs", () => {
   const actual = jest.requireActual("@aws-sdk/client-cloudwatch-logs");
   return {
     ...actual,
     CloudWatchLogsClient: jest.fn(() => ({
       send: jest.fn().mockImplementation((command) => {
-        if (
-          shouldMockThrowError &&
-          command instanceof actual.CreateLogStreamCommand
-        ) {
-          throw new Error("Error creating log stream");
+        if (command instanceof actual.CreateLogStreamCommand) {
+          switch (throwMockError) {
+            case "ResourceAlreadyExistsException": {
+              throw new ResourceAlreadyExistsException({
+                $metadata: {},
+                message: "Resource already exists!",
+              });
+            }
+            case "Error": {
+              throw new Error("Error creating log stream");
+            }
+          }
         }
+
         return {
           message: "",
         };
@@ -44,6 +54,10 @@ describe("pii-redact-handler", () => {
     });
   }
 
+  beforeEach(() => {
+    throwMockError = null;
+  });
+
   it("should not fail when running the handler", async () => {
     const mockDynamoDbClient = mocked(DynamoDBClient);
     mockDynamoDbClient.prototype.send = jest.fn().mockReturnValue({
@@ -71,7 +85,10 @@ describe("pii-redact-handler", () => {
         data: compressedData,
       },
     };
-    const handler = new PiiRedactHandler(mockDynamoDbClient.prototype);
+    const handler = new PiiRedactHandler(
+      mockDynamoDbClient.prototype,
+      mockLogger
+    );
     const result = await handler.handler(event, {});
     expect(result).toStrictEqual({});
   });
@@ -81,7 +98,7 @@ describe("pii-redact-handler", () => {
     mockDynamoDbClient.prototype.send = jest.fn().mockReturnValue({
       Count: 0,
     });
-    shouldMockThrowError = true;
+    throwMockError = "Error";
     const piiData = {
       owner: undefined,
       logGroup: "dummy-log-group",
@@ -103,12 +120,50 @@ describe("pii-redact-handler", () => {
         data: compressedData,
       },
     };
-    const handler = new PiiRedactHandler(mockDynamoDbClient.prototype);
+    const handler = new PiiRedactHandler(
+      mockDynamoDbClient.prototype,
+      mockLogger
+    );
 
     await expect(handler.handler(event, {})).rejects.toThrow(
       new Error("Error creating log stream")
     );
-    shouldMockThrowError = false;
+  });
+
+  it("should not throw when a ResourceAlreadyExistsException error occurs creating a log stream", async () => {
+    const mockDynamoDbClient = mocked(DynamoDBClient);
+    mockDynamoDbClient.prototype.send = jest.fn().mockReturnValue({
+      Count: 0,
+    });
+    throwMockError = "ResourceAlreadyExistsException";
+    const piiData = {
+      owner: undefined,
+      logGroup: "dummy-log-group",
+      logStream: "dummy-log-stream",
+      subscriptionFilters: undefined,
+      messageType: undefined,
+      logEvents: [
+        {
+          id: undefined,
+          timestamp: undefined,
+          message: "{}",
+          extractedFields: undefined,
+        },
+      ],
+    };
+    const compressedData = await encode(JSON.stringify(piiData));
+    const event = {
+      awslogs: {
+        data: compressedData,
+      },
+    };
+    const handler = new PiiRedactHandler(
+      mockDynamoDbClient.prototype,
+      mockLogger
+    );
+
+    const result = await handler.handler(event, {});
+    expect(result).toStrictEqual({});
   });
 
   it("should create log stream when does not exist", async () => {
@@ -138,7 +193,10 @@ describe("pii-redact-handler", () => {
         data: compressedData,
       },
     };
-    const handler = new PiiRedactHandler(mockDynamoDbClient.prototype);
+    const handler = new PiiRedactHandler(
+      mockDynamoDbClient.prototype,
+      mockLogger
+    );
     const result = await handler.handler(event, {});
 
     expect(result).toStrictEqual({});
@@ -171,7 +229,10 @@ describe("pii-redact-handler", () => {
         data: compressedData,
       },
     };
-    const handler = new PiiRedactHandler(mockDynamoDbClient.prototype);
+    const handler = new PiiRedactHandler(
+      mockDynamoDbClient.prototype,
+      mockLogger
+    );
     const result = await handler.handler(event, {});
 
     expect(result).toStrictEqual({});

lambdas/pii-redact/tests/utils.ts

@@ -0,0 +1,9 @@
+import { Logger } from "@aws-lambda-powertools/logger";
+
+export const mockLogger = {
+  info: jest.fn(),
+  critical: jest.fn(),
+  debug: jest.fn(),
+  error: jest.fn(),
+  warn: jest.fn(),
+} as unknown as Logger;