winston-rate-limiter

a simple winston format which can be used to limit the amount of logs getting out from a system. It uses token bucket algorithm internally.

Installation

• from npm

npm install winston-rate-limiter

Usage

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

const { rateLimitingFormat } = require("winston-rate-limiter").utils;

• on a basic level this format can be added to a winston logger or to winston.format.combine
• this format takes a key called config which has multiple optional keywords with key as log_level and value as a dict with below 3 keys

"DEBUG": {
    "tokensPerSec": 1,
    "startingTokens": 1, # optional, default=0
    "maxTokensBalance": 1 # optional, default=Infinity
}

• tokensPerSec: the number of tokens(logs) which will be available for a given log level
• startingTokens: the number of tokens already available at the start of the logging initialisation
• maxTokensBalance: the maximum number of tokens that can be accumulated if the logs for a particular level are not being requested as much as the tokensPerSec allowed. kind of limited burst balance.
• besides providing this config for particular log levels, you can supply a default key with this config.
• if a default is supplied and there is no config supplied for a requested log level then this requested log level will be checked against this default config. useful for scenario where you want an overall rate shared across multiple log levels.
• besides this an optional resultCallback can be supplied which will be called everytime a log record goes through format function
• the resultCallback must accept 2 params result which is a boolean telling whether the log record was filtered or not and record the original log record.

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 winstonformattester 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