pino-template

[![Issues][issues-shield]][issues-url]
[![MIT][license-shield]][license-url]

pino-template

An [Eta][eta-url] template transport for the pino logging library

About The Project

This is a pipeline transport for the [pino.js][pino.js] logging library, which allows you to transform the logging output by applying an [Eta][eta-url] template.

> For those unfamiliar with Eta, perhaps you've encountered [EJS][EJS-url]. Eta templates are very similar to EJS templates.

e.g.

template

``js
<%
// extract the context and this log message from it
const {data: d, context: ctx} = it;
// get the name of the level from the mapping provided as context
const levelName = (ctx?.[d.level] ?? d.level).toUpperCase(); // e.g. "INFO"
%><%=
// output our formatted log message as a string
${
new Date(d.time)
.toISOString()
.substring(0, 19)
} - ${
levelName
} - ${
d.msg
}
%>
`

input

`json
{"levelName":"info","level":30,"time":1531171074631,"msg":"hello world","pid":657,"hostname":"Davids-MBP-3.fritz.box"}
`

result

`txt
2018-07-09T21:17:54 - INFO - hello world
`

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$3

* [![TypeScript][TypeScript]][Typescript-url]
* [![Node.js][Node.js]][Nodejs-url]
* [![Eta][eta]][eta-url]

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Getting Started

$3

While this project has no dependencies, it does have the following peerDependencies:


* [pino][pino.js]@^10.1.0
`sh
npm install "pino@^10.1.0" --save
`
* [eta][eta-url]@^4.0.1
`sh
npm install "eta@^4.0.1" --save
`

* Node versions:
This project is tested on Node 24.12.0 .

* ES Module: This project is only available as an ES module (a.k.a. "ESM") i.e. it probably won't work in CommonJS, except perhaps using [dynamic import][dynamic-import].

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1. Ensure you've installed the prerequisites above.
2. Install this NPM package (pino-template):
`sh
npm install pino-template --save
`

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Usage

Combine pino-template (this module) as part of a [pino transport pipeline][pino-transport-pipeline].

$3

| option | description | example |
| ----------------- | ---------------------------------------------------------------------------------------- | -------------------------------------------------- |
| template | The Eta template as a string. Each log message will be available as it.data. Required. | <%= it.data.msg + it.context.foo %> |
| templateContext | An object which will be made available to the Eta template as it.context . Optional. | {"foo":"bar"} |
| templateOptions | Options which will be passed to the [Eta constructor][eta-constructor] . Optional. | {"debug":false,"cache":false,"autoEscape":false} |

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The example below adds an extra "levelName" property to each JSON log line i.e. it changes this:

`json
{"level":30,"time":1531171074631,"msg":"hello world","pid":657,"hostname":"Davids-MBP-3.fritz.box"}
`

into this:

`json
{"levelName":"info","level":30,"time":1531171074631,"msg":"hello world","pid":657,"hostname":"Davids-MBP-3.fritz.box"}
`

`js
import pino from 'pino'

const logger = pino({
transport: {
pipeline: [{
target: 'pino-template',
options: {
// Provide the Eta template here as the "template" property value. The "it.data"
// object contains the log data (i.e. level, time, msg, hostname etc); while
// the "it.context" object contains whatever you provide as the
// "templateContext" property below
template: <%
const {context, data} = it;
%><%=
JSON.stringify({...data, "levelName":context?.levelMapping?.[data.level] ?? data.level})
%>,
templateContext: { levelMapping: pino.levels.labels },
},
}, {
// Use target: 'pino/file' with STDOUT descriptor 1 to write
// logs without any change.
target: 'pino/file',
options: { destination: 1 }
}]
}
})

logger.info('hello world')
`

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License

Distributed under the MIT license. See LICENSE.txt` for more information.

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Project Link

https://github.com/cunneen/pino-template

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[eta-url]: https://eta.js.org/
[eta-constructor]: https://eta.js.org/docs/4.x.x/api/overview#setting-up-eta
[issues-shield]: https://img.shields.io/github/issues/cunneen/pino-template.svg?style=for-the-badge
[issues-url]: https://github.com/cunneen/pino-template/issues
[license-shield]: https://img.shields.io/github/license/cunneen/pino-template.svg?style=for-the-badge
[license-url]: https://github.com/cunneen/pino-template/blob/master/LICENSE.txt
[product-screenshot]: images/screenshot.png
[Typescript-url]: https://www.typescriptlang.org/
[Nodejs-url]: https://nodejs.org/
[pino.js]: https://getpino.io
[EJS-url]: https://ejs.co/
[dynamic-import]: https://nodejs.org/api/esm.html#import-expressions
[pino-transport-pipeline]: https://getpino.io/#/docs/transports?id=creating-a-transport-pipeline

[Eta]: https://img.shields.io/badge/%CE%B7-Eta-a8b1ff "Eta"
[EJS]: https://img.shields.io/badge/ejs-#B4CA65?logo=ejs&logoColor=fff "EJS"
[TypeScript]: https://img.shields.io/badge/TypeScript-3178C6?logo=typescript&logoColor=fff "TypeScript"
[Node.js]: https://img.shields.io/badge/Node.js-6DA55F?logo=node.js&logoColor=white "Node.js"