WIP

Author: stevebux

internal/datastore/src/healthcheck.ts

@@ -0,0 +1,13 @@
+import { DescribeTableCommand } from "@aws-sdk/client-dynamodb";
+import { DynamoDBDocumentClient } from "@aws-sdk/lib-dynamodb";
+import { LetterRepositoryConfig } from "./letter-repository";
+
+export class DBHealthcheck {
+  constructor(readonly ddbClient: DynamoDBDocumentClient,
+    readonly config: LetterRepositoryConfig) {}
+
+  async check(): Promise<void> {
+    this.ddbClient.send(new DescribeTableCommand({
+      TableName: this.config.lettersTableName}));
+  }
+}

internal/datastore/src/index.ts

@@ -1,3 +1,4 @@
 export * from './types';
 export * from './letter-repository';
+export * from './healthcheck';
 export * from './types';

lambdas/api-handler/src/config/deps.ts

@@ -2,13 +2,14 @@ import { S3Client } from "@aws-sdk/client-s3";
 import { DynamoDBClient } from '@aws-sdk/client-dynamodb';
 import { DynamoDBDocumentClient } from '@aws-sdk/lib-dynamodb';
 import pino from 'pino';
-import { LetterRepository } from '../../../../internal/datastore';
+import { LetterRepository, DBHealthcheck } from '../../../../internal/datastore';
 import { envVars, EnvVars } from "../config/env";
 
 export type Deps = {
   s3Client: S3Client;
   letterRepo: LetterRepository;
-  logger: pino.Logger,
+  dbHealthcheck: DBHealthcheck;
+  logger: pino.Logger;
   env: EnvVars
 };
 
@@ -23,13 +24,25 @@ function createLetterRepository(log: pino.Logger, envVars: EnvVars): LetterRepos
   return new LetterRepository(docClient, log, config);
 }
 
+function createDBHealthcheck(envVars: EnvVars): DBHealthcheck {
+  const ddbClient = new DynamoDBClient({});
+  const docClient = DynamoDBDocumentClient.from(ddbClient);
+  const config = {
+    lettersTableName: envVars.LETTERS_TABLE_NAME,
+    ttlHours: envVars.LETTER_TTL_HOURS
+  };
+
+  return new DBHealthcheck(docClient, config);
+}
+
 export function createDependenciesContainer(): Deps {
 
   const log = pino();
 
   return {
     s3Client: new S3Client(),
     letterRepo: createLetterRepository(log, envVars),
+    dbHealthcheck: createDBHealthcheck(envVars),
     logger: log,
     env: envVars
   };

lambdas/api-handler/src/handlers/__tests__/get-letter-data.test.ts

@@ -18,7 +18,7 @@ import { makeApiGwEvent } from './utils/test-utils';
 import { ValidationError } from '../../errors';
 import * as errors from '../../contracts/errors';
 import { createGetLetterDataHandler } from '../get-letter-data';
-import { S3Client } from '@aws-sdk/client-s3';
+import { Destination, S3Client } from '@aws-sdk/client-s3';
 import pino from 'pino';
 import { LetterRepository } from '../../../../../internal/datastore/src';
 import { EnvVars } from '../../config/env';
@@ -37,7 +37,7 @@ describe('API Lambda handler', () => {
       LETTER_TTL_HOURS: 12960,
       DOWNLOAD_URL_TTL_SECONDS: 60
     } as unknown as EnvVars
-  }
+  } as Deps;
 
   beforeEach(() => {
     jest.clearAllMocks();

lambdas/api-handler/src/handlers/__tests__/get-letters.test.ts

@@ -38,7 +38,7 @@ describe('API Lambda handler', () => {
       DOWNLOAD_URL_TTL_SECONDS: 60,
       MAX_LIMIT: 2500
     } as unknown as EnvVars
-  }
+  } as Deps;
 
   beforeEach(() => {
     jest.clearAllMocks();

lambdas/api-handler/src/handlers/__tests__/get_status.test.ts

@@ -0,0 +1,62 @@
+import { S3, S3Client } from "@aws-sdk/client-s3";
+import { DBHealthcheck } from "../../../../../internal/datastore/src";
+import pino from "pino";
+import { Deps } from "../../config/deps";
+import { makeApiGwEvent } from "./utils/test-utils";
+import { mockDeep } from "jest-mock-extended";
+import { Context } from "aws-lambda";
+import { createGetStatusHandler } from "../get-status";
+
+describe('API Lambda handler', () => {
+
+  const mockedDeps: jest.Mocked<Deps> = {
+    s3Client: { send: jest.fn()} as unknown as S3Client,
+    dbHealthcheck: {check: jest.fn()} as unknown as DBHealthcheck,
+    logger: { info: jest.fn(), error: jest.fn() } as unknown as pino.Logger,
+    env: {
+      SUPPLIER_ID_HEADER: 'nhsd-supplier-id',
+      APIM_CORRELATION_HEADER: 'nhsd-correlation-id'
+    }
+  } as Deps;
+
+  beforeEach(() => {
+    jest.clearAllMocks();
+    jest.resetModules();
+  });
+
+  it('passes if S3 and DynamoDB are available', async() => {
+
+    const event = makeApiGwEvent({path: '/_status',
+      headers: {'nhsd-supplier-id': 'supplier1', 'nhsd-correlation-id': 'correlationId'},
+      pathParameters: {id: 'id1'}
+    });
+
+    const getLetterDataHandler = createGetStatusHandler(mockedDeps);
+    const result = await getLetterDataHandler(event,  mockDeep<Context>(), jest.fn());
+
+    expect(result).toEqual({
+      statusCode: 200,
+      body: JSON.stringify({}, null, 2),
+    });
+  });
+
+  it('fails if S3 is unavailable', async() => {
+    mockedDeps.s3Client = {
+      send: jest.fn().mockRejectedValue(new Error('unexpected error'))
+    } as unknown as S3Client;
+
+    const event = makeApiGwEvent({path: '/_status',
+      headers: {'nhsd-supplier-id': 'supplier1', 'nhsd-correlation-id': 'correlationId'},
+      pathParameters: {id: 'id1'}
+    });
+
+
+    const getLetterDataHandler = createGetStatusHandler(mockedDeps);
+    const result = await getLetterDataHandler(event,  mockDeep<Context>(), jest.fn());
+
+    expect(result).toEqual(expect.objectContaining({
+      statusCode: 500
+    }));
+  });
+
+});

lambdas/api-handler/src/handlers/__tests__/patch-letter.test.ts

@@ -57,7 +57,7 @@ describe('patchLetter API Handler', () => {
       LETTER_TTL_HOURS: 12960,
       DOWNLOAD_URL_TTL_SECONDS: 60
     } as unknown as EnvVars
-  }
+  } as Deps;
 
   it('returns 200 OK with updated resource', async () => {
     const event = makeApiGwEvent({

lambdas/api-handler/src/handlers/get-status.ts

@@ -0,0 +1,42 @@
+import { APIGatewayProxyHandler } from "aws-lambda";
+import { Deps } from "../config/deps";
+import { ListBucketsCommand, S3Client } from "@aws-sdk/client-s3";
+import { validateCommonHeaders } from "../utils/validation";
+import { mapErrorToResponse } from "../mappers/error-mapper";
+
+export function createGetStatusHandler(deps: Deps): APIGatewayProxyHandler {
+
+  return async(event) => {
+
+    const commonHeadersResult = validateCommonHeaders(event.headers, deps);
+
+    if (!commonHeadersResult.ok) {
+      return mapErrorToResponse(commonHeadersResult.error, commonHeadersResult.correlationId, deps.logger);
+    }
+
+    try {
+      deps.dbHealthcheck.check();
+      s3HealthCheck(deps.s3Client);
+
+      deps.logger.info({
+        description: 'Healthcheck passed',
+        supplierId: commonHeadersResult.value.supplierId
+      });
+
+      return {
+        statusCode: 200,
+        body: JSON.stringify({}, null, 2)
+      };
+    } catch (error) {
+      return mapErrorToResponse(error, commonHeadersResult.value.correlationId, deps.logger);
+  }
+  }
+}
+
+
+function s3HealthCheck(s3Client: S3Client) {
+  const command: ListBucketsCommand = new ListBucketsCommand({
+    MaxBuckets: 1
+  });
+  s3Client.send(command);
+}

lambdas/api-handler/src/services/__tests__/letter-operations.test.ts

@@ -133,7 +133,7 @@ describe('getLetterDataUrl function', () => {
         APIM_CORRELATION_HEADER: 'nhsd-correlation-id',
         DOWNLOAD_URL_TTL_SECONDS: 60
   };
-  const deps: Deps = { s3Client, letterRepo, logger, env };
+  const deps: Deps = { s3Client, letterRepo, logger, env } as Deps;
 
   it('should return pre signed url successfully', async () => {