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5.1.2 • Public • Published


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A Grafana Loki transport for the nodejs logging library Winston.


This Winston transport is used similarly to other Winston transports. Require winston and define a new LokiTransport() inside its options when creating it.


LokiTransport() takes a Javascript object as an input. These are the options that are available, required in bold:

Parameter Description Example Default
host URL for Grafana Loki http://localhost:3100 null
interval The interval at which batched logs are sent in seconds 30 5
json Use JSON instead of Protobuf for transport true false
batching If batching is not used, the logs are sent as they come true true
clearOnError Discard any logs that result in an error during transport true false
replaceTimestamp Replace any log timestamps with true false
labels custom labels, key-value pairs { module: 'http' } null
format winston format ( simple() null
gracefulShutdown Enable/disable graceful shutdown (wait for any unsent batches) false true


With default formatting:

const { createLogger, transports } = require("winston");
const LokiTransport = require("winston-loki");
const options = {
  transports: [
    new LokiTransport({
      host: "http://localhost:3100"
const logger = createLogger(options);

You can set custom labels in every log as well like this:

logger.debug({ message: 'test', labels: { 'key': 'value' } })

TODO: Add custom formatting example



Running a local Loki for testing is probably required, and the easiest way to do that is to follow this guide: After that, Grafana Loki instance is available at http://localhost:3100, with a Grafana instance running at http://localhost:3000. Username admin, password admin. Add the Loki source with the URL http://loki:3100, and the explorer should work.

Refer to for documentation about the available endpoints, data formats etc.


npm install
npm link
cd ~/your_project
npm link winston-loki
npm install

And you should have a working, requirable winston-loki package under your project's node_modules. After the link has been established, any changes to winston-loki should show on rerun of the software that uses it.

Run tests

npm test

Write new ones under /test


npm i winston-loki

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