feat(logger): add log filtering functional

Implemented log filtering to allow users to specify criteria for filtering which logs are captured
and processed

close #38

example/basic.ts

@@ -9,7 +9,12 @@ const app = new Elysia({
       config: {
         ip: true,
         customLogFormat:
-          '🦊 {now} {level} {duration} {method} {pathname} {status} {message} {ip}'
+          '🦊 {now} {level} {duration} {method} {pathname} {status} {message} {ip}',
+        logFilter: {
+          level: ['ERROR', 'WARNING'],
+          status: [500, 404],
+          method: 'GET'
+        }
       }
     })
   )

src/logger.ts

@@ -14,6 +14,55 @@ import {
   HttpError
 } from './types'
 
+/**
+ * Filters log messages.
+ *
+ * @param {LogLevel} logLevel The log level.
+ * @param {number} status The status code.
+ * @param {string} method The method.
+ * @param {Options} options The options.
+ * @returns {boolean} `true` if the log message should be logged, otherwise `false`.
+ */
+function filterLog(
+  logLevel: LogLevel,
+  status: number,
+  method: string,
+  options?: Options
+): boolean {
+  const filter = options?.config?.logFilter
+
+  if (!filter) return true
+
+  // Level
+  if (filter.level) {
+    if (Array.isArray(filter.level)) {
+      if (!filter.level.includes(logLevel)) return false
+    }
+  } else {
+    if (filter.level !== logLevel) return false
+  }
+
+  // Status
+  if (filter.status) {
+    if (Array.isArray(filter.status)) {
+      if (!filter.status.includes(status)) return false
+    }
+  } else {
+    if (filter.status !== status) return false
+  }
+
+  // Method
+  if (filter.method) {
+    if (Array.isArray(filter.method)) {
+      if (!filter.method.includes(method)) return false
+    }
+  } else {
+    if (filter.method !== method) return false
+  }
+
+  return true
+}
+
 /**
  * Logs a message.
  *
@@ -30,6 +79,10 @@ function log(
   store: StoreData,
   options?: Options
 ): void {
+  if (!filterLog(level, data.status || 200, request.method, options)) {
+    return
+  }
+
   const logMessage = buildLogMessage(level, request, data, store, options)
   console.log(logMessage)
 }

src/types.ts

@@ -48,6 +48,11 @@ interface Options {
   config?: {
     ip?: boolean
     customLogFormat?: string
+    logFilter?: {
+      level?: LogLevel | LogLevel[]
+      method?: string | string[]
+      status?: number | number[]
+    } | null
   }
 }
 

test/logixlysia.test.ts

@@ -124,3 +124,106 @@ describe('Logixlysia with IP logging disabled', () => {
     expect(error).toBeInstanceOf(Error)
   })
 })
+
+describe('Logixlysia with log filtering enabled', () => {
+  let server: Elysia
+  let app: any
+  let logs: string[] = []
+
+  beforeAll(() => {
+    server = new Elysia()
+      .use(
+        logger({
+          config: {
+            logFilter: {
+              level: 'INFO',
+              status: [200, 404],
+              method: 'GET'
+            }
+          }
+        })
+      )
+      .get('/', () => '🦊 Logixlysia Getting')
+      .post('logixlysia', () => '🦊 Logixlysia Posting')
+      .listen(3000)
+
+    app = edenTreaty<typeof server>('http://127.0.0.1:3000')
+  })
+
+  beforeEach(() => {
+    logs = []
+  })
+
+  it("Logs 'GET' requests with status 200 or 404 when log filtering criteria are met", async () => {
+    const requestCount = 5
+
+    for (let i = 0; i < requestCount; i++) {
+      logs.push((await app.get('/')).data)
+    }
+
+    expect(logs.length).toBe(requestCount)
+    logs.forEach(log => {
+      expect(log).toMatch('🦊 Logixlysia Getting')
+    })
+  })
+
+  it("Doesn't log 'POST' requests when log filtering criteria are not met", async () => {
+    const requestCount = 5
+
+    for (let i = 0; i < requestCount; i++) {
+      await app.post('/logixlysia', {})
+    }
+
+    expect(logs.length).toBe(0)
+  })
+
+  const otherMethods = ['PUT', 'DELETE', 'PATCH', 'HEAD'] // OPTIONS is failed (IDK why)
+  otherMethods.forEach(async method => {
+    it(`Logs '${method}' requests with status 200 or 404 when log filtering criteria are met`, async () => {
+      const requestCount = 5
+
+      for (let i = 0; i < requestCount; i++) {
+        logs.push((await app[method.toLowerCase()]('/')).data)
+      }
+
+      expect(logs.length).toBe(requestCount)
+    })
+  })
+})
+
+describe('Logixlysia with log filtering disabled', () => {
+  let server: Elysia
+  let app: any
+  let logs: string[] = []
+
+  beforeAll(() => {
+    server = new Elysia()
+      .use(
+        logger({
+          config: {
+            logFilter: null
+          }
+        })
+      )
+      .get('/', () => '🦊 Logixlysia Getting')
+      .post('logixlysia', () => '🦊 Logixlysia Posting')
+      .listen(3000)
+
+    app = edenTreaty<typeof server>('http://127.0.0.1:3000')
+  })
+
+  beforeEach(() => {
+    logs = []
+  })
+
+  it('Logs all requests when log filtering is disabled', async () => {
+    const requestCount = 5
+
+    for (let i = 0; i < requestCount; i++) {
+      logs.push((await app.get('/')).data)
+      logs.push((await app.post('/logixlysia', {})).data)
+    }
+
+    expect(logs.length).toBe(requestCount * 2)
+  })
+})