Logging in Typescript using Bunyan and Logentries

Question

I want to setup remote Logging using logentries.com in my ionic app.

This an extract from my package.json:

  "dependencies": {

    "bunyan": "^1.8.5",
    "bunyan-logentries": "^1.2.0",

  },
  "devDependencies": {
    "@types/bunyan": "0.0.35",
    "@types/bunyan-logentries": "0.1.30",
    "typescript": "2.0.9"
  },

Code

import {createStream} from "bunyan-logentries";
import * as Logger from "bunyan";

// ...
constructor() {
    let token = 'xxxxxxxxxxxxxxxxx';
    let log = Logger.createLogger({
      name: '',
      streams: [{
        level: 'info',
        stream: createStream({token: token}),
        type: 'raw'
       }]
    });
    log.info("Created log");
 }

The problem

My IDE does not warn me about any errors. But as soon as I run the app I get the following error:

exists is not a function. (In 'exists(pkgPath)', 'exists' is undefined)

findPackage@http://localhost:8101/build/main.js:131257:18
register@http://localhost:8101/build/main.js:131332:31
http://localhost:8101/build/main.js:112585:50
http://localhost:8101/build/main.js:113391:34
__webpack_require__@http://localhost:8101/build/main.js:20:34
http://localhost:8101/build/main.js:129423:37
__webpack_require__@http://localhost:8101/build/main.js:20:34
http://localhost:8101/build/main.js:29972:95
__webpack_require__@http://localhost:8101/build/main.js:20:34
http://localhost:8101/build/main.js:80592:90
__webpack_require__@http://localhost:8101/build/main.js:20:34
http://localhost:8101/build/main.js:59390:96
__webpack_require__@http://localhost:8101/build/main.js:20:34
http://localhost:8101/build/main.js:59495:94
__webpack_require__@http://localhost:8101/build/main.js:20:34
http://localhost:8101/build/main.js:128048:94
__webpack_require__@http://localhost:8101/build/main.js:20:34
http://localhost:8101/build/main.js:116775:92
__webpack_require__@http://localhost:8101/build/main.js:20:34
http://localhost:8101/build/main.js:149625:89
__webpack_require__@http://localhost:8101/build/main.js:20:34
http://localhost:8101/build/main.js:66:37
global code@http://localhost:8101/build/main.js:67:12 

I think the core of the problem is that the @types don't match the actual node modules, but it is unclear how this is supposed to be addressed.

Answer 1

I have faced the same issue. The bunyan-logentries module depends on le_node: the logentries module for node.

le_node uses the net and tls modules that are not available from the browser.

To move on, I have implemented a custom bunyan stream that sends the logs to logentries via their REST API. It is straightforward to code and it works.

Here is a sample code to illustrate this solution.

The LoggerService that creates Bunyan Instances:

@Injectable()
export class LoggerService {
    constructor(private http: Http) {
    }

    public create(name: string): Logger{
        return Bunyan.createLogger({
            name: name,
            streams: [{
                stream: new LogentriesBunyanStream(AppConfig.LogEntries.token, this.http),
                type: 'raw'
            }]
        });
    }
}

The bunyan custom stream that sends logs to logentries:

export class LogentriesBunyanStream extends Writable {
    private token: string;
    private http: Http;
    
    constructor(token: string, http: Http) {
        super({objectMode: true});
        this.http = http;
        this.token = token;
    }
        
    public _write(rec: any, encoding?: string, cb?: Function) {
        // Replace the level code with a friendly string 
        rec.level = LogentriesBunyanStream.resolveLevel(rec.level);
        
        // Send the post request to logentries
        // https://docs.logentries.com/docs/http-post
        const LOGENTRIES_URL = "https://webhook.logentries.com/noformat/logs/";
        let headers = new Headers();
        headers.append("Content-Type", 'application/json');
        let requestoptions = new RequestOptions({
            method: RequestMethod.Post,
            headers: headers,
            body: JSON.stringify(rec)
        });
        this.http.request(LOGENTRIES_URL + this.token, requestoptions).toPromise().then((response) => {
            cb();
        }).catch((error) =>{
            console.log("faield to send log to the logentries server");
        });
    };

    private static resolveLevel(bunyanLevel) {
        let levelToName = {
            10: 'DEBUG',
            20: 'DEBUG',
            30: 'INFO',
            40: 'WARN',
            50: 'ERROR',
            60: 'CRIT'
        };
        return levelToName[bunyanLevel] || 'INFO';
    }
};

Maybe it helps,

Regards.