Refactor ElasticSearchBackend to make it testable

packages/backend-tools/src/elastic-search/ElasticSearchBackend.ts

@@ -0,0 +1,98 @@
+import { v4 as uuidv4 } from 'uuid'
+
+import { LoggerBackend } from '../logger/interfaces'
+import {
+  ElasticSearchClient,
+  ElasticSearchClientOptions,
+} from './ElasticSearchClient'
+
+export interface ElasticSearchBackendOptions
+  extends ElasticSearchClientOptions {
+  flushInterval?: number
+  indexPrefix?: string
+}
+
+export type UuidProvider = () => string
+
+export class ElasticSearchBackend implements LoggerBackend {
+  private readonly buffer: string[]
+
+  constructor(
+    private readonly options: ElasticSearchBackendOptions,
+    private readonly client: ElasticSearchClient = new ElasticSearchClient(
+      options,
+    ),
+    private readonly uuidProvider: UuidProvider = uuidv4,
+  ) {
+    this.buffer = []
+    this.start()
+  }
+
+  public debug(message: string): void {
+    this.buffer.push(message)
+  }
+
+  public log(message: string): void {
+    this.buffer.push(message)
+  }
+
+  public warn(message: string): void {
+    this.buffer.push(message)
+  }
+
+  public error(message: string): void {
+    this.buffer.push(message)
+  }
+
+  private start(): void {
+    // eslint-disable-next-line @typescript-eslint/no-misused-promises
+    setInterval(async () => {
+      await this.flushLogs()
+    }, this.options.flushInterval ?? 10000)
+  }
+
+  private async flushLogs(): Promise<void> {
+    if (!this.buffer.length) {
+      return
+    }
+
+    try {
+      const index = await this.createIndex()
+
+      // copy buffer contents as it may change during async operations below
+      const batch = [...this.buffer]
+
+      //clear buffer
+      this.buffer.splice(0)
+
+      const documents = batch.map(
+        (log) =>
+          ({
+            id: this.uuidProvider(),
+            ...JSON.parse(log),
+          } as object),
+      )
+
+      const success = await this.client.bulk(documents, index)
+
+      if (!success) {
+        throw new Error('Failed to push liogs to Elastic Search node')
+      }
+    } catch (error) {
+      console.log(error)
+    }
+  }
+
+  private async createIndex(): Promise<string> {
+    const now = new Date()
+    const indexName = `${
+      this.options.indexPrefix ?? 'logs-'
+    }-${now.getFullYear()}.${now.getMonth()}.${now.getDay()}`
+
+    const exist = await this.client.indexExist(indexName)
+    if (!exist) {
+      await this.client.indexCreate(indexName)
+    }
+    return indexName
+  }
+}

packages/backend-tools/src/elastic-search/ElasticSearchClient.ts

@@ -0,0 +1,40 @@
+import { Client } from '@elastic/elasticsearch'
+
+export interface ElasticSearchClientOptions {
+  node: string
+  apiKey: string
+}
+
+// hides complexity of ElastiSearch client API
+export class ElasticSearchClient {
+  private readonly client: Client
+
+  constructor(private readonly options: ElasticSearchClientOptions) {
+    this.client = new Client({
+      node: options.node,
+      auth: {
+        apiKey: options.apiKey,
+      },
+    })
+  }
+
+  public async bulk(documents: object[], index: string): Promise<boolean> {
+    const operations = documents.flatMap((doc: object) => [
+      { index: { _index: index } },
+      doc,
+    ])
+
+    const bulkResponse = await this.client.bulk({ refresh: true, operations })
+    return bulkResponse.errors
+  }
+
+  public async indexExist(index: string): Promise<boolean> {
+    return await this.client.indices.exists({ index })
+  }
+
+  public async indexCreate(index: string): Promise<void> {
+    await this.client.indices.create({
+      index,
+    })
+  }
+}

packages/backend-tools/src/index.ts

@@ -1,5 +1,5 @@
+export * from './elastic-search/ElasticSearchBackend'
 export * from './env'
-export * from './logger/ElasticSearchBackend'
 export * from './logger/interfaces'
 export * from './logger/LogFormatterEcs'
 export * from './logger/LogFormatterJson'