feat(EthereumRegistryWriter): health endpoint

src/Configuration.ts

@@ -44,6 +44,7 @@ export interface Configuration extends LoggingConfiguration, BitcoinRPCConfigura
   readonly bitcoinFeeEstimateMode: 'CONSERVATIVE' | 'ECONOMICAL'
   readonly bitcoinFeeRate: number
 
+  readonly ethereumRegistryWriterApiPort: number
   readonly ethereumRpcUrl: string
   readonly ethereumChainId: number
   readonly ethereumRegistryContractAddress: string
@@ -137,6 +138,7 @@ export const DefaultConfiguration: Configuration = {
 
   forceBlockHeight: undefined,
 
+  ethereumRegistryWriterApiPort: 18081,
   ethereumRpcUrl: 'http://localhost:8545',
   ethereumChainId: 4,
   ethereumRegistryContractAddress: '',

src/EthereumRegistryWriter/Business.ts

@@ -27,7 +27,12 @@ export interface Arguments {
   readonly configuration: Configuration
 }
 
+export interface Health {
+  readonly healthy: boolean
+}
+
 export interface Business {
+  readonly getHealth: () => Promise<Health>
   readonly createDbIndices: () => Promise<void>
   readonly insertClaimIdFilePair: (claimId: string, claimFile: string) => Promise<void>
   readonly setBatchDirectory: (claimFiles: ReadonlyArray<string>, ipfsDirectoryHash: string) => Promise<void>
@@ -83,6 +88,10 @@ export const Business = ({
   const businessLogger: Pino.Logger = childWithFileName(logger, __filename)
   const claimAnchorReceiptsCollection: Collection<DbEntry> = db.collection('claimAnchorReceipts')
 
+  const getHealth = async () => ({
+    healthy: true,
+  })
+
   const createDbIndices = async () => {
     await claimAnchorReceiptsCollection.createIndex({ claimId: 1 }, { unique: true })
     await claimAnchorReceiptsCollection.createIndex({ claimFile: 1 }, { unique: true })
@@ -351,6 +360,7 @@ export const Business = ({
   }
 
   return {
+    getHealth,
     createDbIndices,
     insertClaimIdFilePair,
     setBatchDirectory,

src/EthereumRegistryWriter/EthereumRegistryWriter.ts

@@ -14,6 +14,7 @@ import { Router } from './Router'
 import { Scheduler } from './Scheduler'
 
 export interface EthereumRegistryWriterConfiguration extends LoggingConfiguration {
+  readonly apiPort: number
   readonly mongodbUrl: string
   readonly rabbitmqUrl: string
   readonly exchanges: ExchangeConfiguration
@@ -74,7 +75,10 @@ export const EthereumRegistryWriter = async (configuration: EthereumRegistryWrit
       business,
       ethereumRegistryContract,
     },
-    exchange: configuration.exchanges,
+    configuration: {
+      apiPort: configuration.apiPort,
+      exchange: configuration.exchanges,
+    },
   })
   await router.start()
 
@@ -95,6 +99,7 @@ export const EthereumRegistryWriter = async (configuration: EthereumRegistryWrit
   return async () => {
     logger.info('Stopping EthereumRegistryWriter...')
     await scheduler.stop()
+    await router.stop()
     logger.debug('Stopping EthereumRegistryWriter Messaging...')
     await messaging.stop()
     logger.info('EthereumRegistryWriter Messaging Stopped')

src/EthereumRegistryWriter/Router.ts

@@ -1,4 +1,8 @@
+import { Server } from 'http'
+import Koa from 'koa'
+import KoaRouter from 'koa-router'
 import Pino from 'pino'
+import { promisify } from 'util'
 
 import { EthereumRegistryContract } from 'Helpers/EthereumRegistryContract'
 import { childWithFileName } from 'Helpers/Logging'
@@ -9,6 +13,11 @@ import { Messaging } from 'Messaging/Messaging'
 import { Business } from './Business'
 import { ExchangeConfiguration } from './ExchangeConfiguration'
 
+export interface Configuration {
+  readonly apiPort: number
+  readonly exchange: ExchangeConfiguration
+}
+
 export interface Dependencies {
   readonly logger: Pino.Logger
   readonly messaging: Messaging
@@ -18,11 +27,12 @@ export interface Dependencies {
 
 export interface Arguments {
   readonly dependencies: Dependencies
-  readonly exchange: ExchangeConfiguration
+  readonly configuration: Configuration
 }
 
 export interface Router {
   readonly start: () => Promise<void>
+  readonly stop: () => Promise<void>
 }
 
 export const Router = ({
@@ -32,9 +42,15 @@ export const Router = ({
     business,
     ethereumRegistryContract,
   },
-  exchange,
+  configuration: {
+    apiPort,
+    exchange,
+  },
 }: Arguments): Router => {
   const routerLogger = childWithFileName(logger, __filename)
+  const koa = new Koa()
+  const koaRouter = new KoaRouter()
+  let server: Server
 
   const start = async () => {
     await messaging.consume(exchange.claimIpfsHash, onClaimIPFSHash)
@@ -61,6 +77,15 @@ export const Router = ({
       .on('error', (error: any) => {
         logger.error({ error }, 'onCidAdded error')
       })
+
+    server = koa.listen(apiPort, '0.0.0.0')
+  }
+
+  const stop = async () => {
+    routerLogger.debug('Stopping API Router...')
+    server.unref()
+    await promisify(server.close.bind(server))
+    routerLogger.info('API Router stopped')
   }
 
   const onClaimIPFSHash = async (message: any) => {
@@ -152,7 +177,16 @@ export const Router = ({
     }
   }
 
+  const getHealth = async (context: KoaRouter.IRouterContext, next: () => Promise<any>) => {
+    context.body = await business.getHealth()
+  }
+
+  koaRouter.get('/health', getHealth)
+  koa.use(koaRouter.allowedMethods())
+  koa.use(koaRouter.routes())
+
   return {
     start,
+    stop,
   }
 }

src/EthereumRegistryWriter/index.ts

@@ -19,6 +19,7 @@ const logger: Pino.Logger = Pino({
 EthereumRegistryWriter({
   loggingLevel: configuration.loggingLevel,
   loggingPretty: configuration.loggingPretty,
+  apiPort: configuration.ethereumRegistryWriterApiPort,
   mongodbUrl: configuration.mongodbUrl,
   rabbitmqUrl: configuration.rabbitmqUrl,
   ipfs: {