Log parser app

A command line node.js application, which parses the input log file.

The application finds all the log messages with the level error and prints them into the output file. Formats of input and output files are described below.

Pre-requisites

• Node.js v10+
• TypeScript

Usage

npm install
npm run build
node parser.js --input ./app.log --output ./errors.json

#Input

Format

<ISO Date> - <Log Level> - {"transactionId: "<UUID>", "details": "<message event/action description>", "err": "<Optional, error description>", ...<additional log information>}

Example

2044-08-09T02:12:51.253Z - info - {"transactionId":"9abc55b2-807b-4361-9dbe-aa88b1b2e978","details":"Service is started"}
2021-08-09T02:12:51.254Z - debug - {"transactionId":"9abc55b2-807b-4361-9dbe-aa88b1b2e978","details":"About to request the user information","userId": 10}
2021-08-09T02:12:51.254Z - debug - {"transactionId":"9abc55b2-807b-4361-9dbe-aa88b1b2e978","details":"About to request user orders list","userId": 10}
2021-08-09T02:12:51.255Z - info - {"transactionId":"9abc55b2-807b-4361-9dbe-aa88b1b2e821","details":"Service is started"}
2021-08-09T02:12:51.257Z - debug - {"transactionId":"9abc55b2-807b-4361-9dbe-aa88b1b2e821","details":"About to request the user information","userId": 16}
2021-08-09T02:12:51.257Z - debug - {"transactionId":"9abc55b2-807b-4361-9dbe-aa88b1b2e978","details":"User information is gathered","user":{"id":10,"name":"Alice"}}
2021-08-09T02:12:51.258Z - debug - {"transactionId":"9abc55b2-807b-4361-9dbe-aa88b1b2e821","details":"About to request user orders list","userId":16}
2021-08-09T02:12:51.259Z - error - {"transactionId":"9abc55b2-807b-4361-9dbe-aa88b1b2e978","details":"Cannot find user orders list","code": 404,"err":"Not found"}
2021-08-09T02:12:51.259Z - debug - {"transactionId":"9abc55b2-807b-4361-9dbe-aa88b1b2e821","details":"User information is retrieved","user": {"id": 16, "name": "Michael"}}
2021-08-09T02:12:51.262Z - debug - {"transactionId":"9abc55b2-807b-4361-9dbe-aa88b1b2e821","details":"User information is retrieved","user":{"id":16,"orders":[{"id":472,"items":{"id":7,"price":7.12}}]}}
2021-08-09T02:12:51.264Z - warn - {"transactionId":"9abc55b2-807b-4361-9dbe-aa88b1b2e978","details":"Service finished with error","code":404,"err":"Cannot find user orders list"}
2021-08-09T02:12:51.265Z - info - {"transactionId":"9abc55b2-807b-4361-9dbe-aa88b1b2e821","details":"Service is successfully finished"}

Output

Format

[{"timestamp": <Epoch Unix Timestamp>, "loglevel": "<loglevel>", "transactionId: "<UUID>", "err": "<Error message>" }]

Example

[{"timestamp":1628475171259,"loglevel":"error","transactionId":"9abc55b2-807b-4361-9dbe-aa88b1b2e978","err":"Not found"}]

Contributions

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Please make sure to update tests as appropriate.