winston-opentelemetry-format

a simple winston format which can be used to format logs to opentelemetry specification coming out from a system. it also provides some additional size control over log body and log attributes

Installation

• from npm

npm install winston-opentelemetry-format

Usage

• check example for a complete example
• the format is available as

const { opentelemetryLogFormat } = require("winston-opentelemetry-format").utils;

• the format takes a single param which is an object with following keys and thier respective values.
• filename: filename of the logger which is doing the logging, usually pass __filename, the value is shown in resource.pathname
• useTraces: use the traces information to enrich logs or not(trace_id and span_id)
• restrictAttributesTo: array of attributes to which log's attributes should be restricted, any extra attributes passed inside log will be added against _meta inside attributes. value for _meta key is converted to string later on.
• metaCharacterLimit: the max length of value for _meta in output logs' attributes, if the length of the calculated _meta exceeds this limit the value of _meta will be trimmed to specified length. also an attribute _meta_original_length is added with value as the length of original _meta and _meta_too_large with value true for debugging purpose.
• bodyCharacterLimit: the max length of value for log body, if the length of log body exceeds this limit the value of log body will be trimmed to specified value. also an attribute _body_original_length is added with value as the length of original log body and _body_too_large with value true for debugging purpose.
• discardAttributesFrom: an array of attributes which needs to be skipped when exporting logs

Local development and testing

• build the docker-image of the package docker-compose build --no-cache
• run the image docker-compose up
• go to the container docker exec -it winston_optl_format_tester sh
• to run tests first install jest npm install jest then jest to run the actual tests.

generate package-lock.json

• npm i --package-lock-only from container

License

• this project is licensed under MIT License