koa-tracer 1.7.11
Install from the command line:
Learn more about npm packages
$ npm install @uswitch/koa-tracer@1.7.11
Install via package.json:
"@uswitch/koa-tracer": "1.7.11"
About this version
A Koa middleware for tracing your request's lifecycle, efficiently & effectively.
This package is a Koa middleware to allow tracing the lifecycle of requests.
It tries to implement the following features;
- π Namespaced traces - Group messages by namespace
- β± Namespaced relative time diffs - Display the time difference in
ms
between events in a namespace. - π Global relative time diffs - Display time difference between request start and the trace event.
- π Decoupled errors - Log errors separately to handling them.
- π Per-request trace - Be able to reference all traces back to a single request!
All of this is designed to make it easy to rebuild an exact picture of what's happening in your code.
npm install @uswitch/koa-tracer
import Koa from 'koa'
import tracer, { eventTrace, eventError } from '@uswitch/koa-tracer'
const app = new Koa()
app.use(tracer())
app.on('koa-tracer:trace', Logger.log)
app.on('koa-tracer:error', Logger.err)
app.on(eventTrace, Logger.log)
app.on(eventError, Logger.err)
This package uses Event
Emitters to decouple the
handling of runtime tracing and logging. This means that you can
decide how you want to handle traces and errors separately with the
koa-tracer:trace
& koa-tracer:error
events.
However, all traces and errors are available in Koa's context at the end of the request to be used in access logs, or whatever else you might want.
-
ctx [Object]
- the Koactx
object -
namespace [String]
- A namespace for the trace message (optional) -
message [String/Object]
- The details of the trace message
-
ctx [Object]
- the Koactx
object -
err [String/Object/Error]
- The details of the error
A trace object looks like this;
{
"time": "Date" // Date for when that trace was logged
"timeDiff": 12 // Diff in `ms` between this and the first trace in namspace
"initDiff": 30 // Diff in `ms` between this and start of request
"msg": "Foo bar" // The message passed into the trace
[other properties] // Any other properties passed in
}
An error object looks like this;
{
"time": "Date" // Date for when that error was logged
"msg": "Foo bar" // The message passed into the error
[other properties] // Any other properties passed in
}
The state object, after a request, looks like this;
{
"traceStart": "Date" /* Date when the request started */
"trace": {
"__general": {
traces: [ /* List of traces without namespace */ ],
tracesLength: 50,
timeDiff: 12,
initDiff: 12
},
"namespace": {
traces: [ /* List of traces in `namespace` */ ],
tracesLength: 50,
timeDiff: 12,
initDiff: 12
}
}
"errorsCount": 12 /* The number of errors occured in this request */
"errors": [
/* List of errors */
]
}
The following events are fired on trace
and error
logging
completion.
koa-tracer:trace => ({ ctx, key, trace })
koa-tracer:error => ({ ctx, error, original })
N.B. These events are called with Objects
They can be imported from the koa-tracer
module, as
import { eventTrace, eventError } from 'koa-tracer'
Thanks goes to these wonderful people (emoji key):
Dom Charlesworth π» π π€ π |
---|
This project follows the all-contributors specification. Contributions of any kind welcome!