Bunyan Transport for GKE (Google Kubernetes Engine) using Stackdriver
npm install bunyan-gke-stackdriverSimple bunyan transport to leverage GKE (Google Kubernetes Engine) logging configuration for Stackdriver
Just configure this transport for the logger:
``js
const Bunyan = require('bunyan');
const {createStream} = require('bunyan-gke-stackdriver');
const logger = Bunyan.createLogger({
name: 'MyLogName',
streams: [createStream()],
});
`
Optionally, you can configure the log level for the transport and the final output stream
(stdout by default).
`js
const Bunyan = require('bunyan');
const {createStream} = require('bunyan-gke-stackdriver');
const logger = Bunyan.createLogger({
name: 'warnings',
streams: [createStream(Bunyan.WARN, process.stderr)],
});
`
If your node application is deployed on GKE, and you've enabled logging for it (the default); all
your logs will end up in Stackdriver viewer but won't be very readable, and won't be using most
of Stackdriver features.
Bunyan uses structured logging, but with a different schema than stackdriver expect to make take
advantange of it's features.
Some of the features enabled by using this module:
- Show the correct severity (level) in stackdriver
- Show the msg in the summary. (Stackdriver expects a message key instead of msg)
- Render information about the request.
- Track errors in Stackdriver Error Reporting
When using bunyan you can configure transports (streams in reality). If no one is configured, logsstdout
go to . In our case, we want them to go to stdout but with a different format. A format
that is compatible with what GKE has configured for log recolection.
So, in essence all you need to do is configure this module as the stream.
`js
const Bunyan = require('bunyan');
const {createStream} = require('bunyan-gke-stackdriver');
const logger = Bunyan.createLogger({
name: 'MyLogName',
streams: [createStream()],
});
`
So, what happens when you do logger.info('hello world')?
First, bunyan creates a log record something like {v: 1, level: 30, msg: 'hello world', ...}.stdout
Then, is passed to the configured strem, which if none was configured, is simply sending all to
Second, since you are running on a docker container within a node in GKE; docker will wrap that log
entry into something like
`json`
{
"stream": "stdout",
"time": "2018-08-24T12:41:50.987184687Z",
"log": "{\"level\":30,\"time\":1535114510986,\"msg\":\"hello world\"...}"
}
Lastly, since you have logging configured for GKE, there a fluentd daemon on each node. fluentd
aggregates logs from all your containers, transform them based on it's configuration, and finally
exports them. On GKE, fluentd is configured to export log entries to stackdriver. Also, it's
configured to unwrap the docker log entry and parse your original entry. It will recognize some fields
as part of the stackdriver schema and use them. But mostly it will pass all of them to stackdriver.
So, to be a good citizen with stackdriver and the fluentd configuration in GKE, we need to make a
few changes to the original entry.
1. Use message instead of msgerr.stack
2. When logging an error, use as the value for messagehttpRequest
3. When logging an http request, use to log the details about itlevel
4. Map to severity
For more information about the stackdriver log entry schema check:
- General: https://cloud.google.com/logging/docs/reference/v2/rest/v2/LogEntry
- For errrors: https://cloud.google.com/error-reporting/docs/formatting-error-messages
When in bunyan you log like:
`js`
logger.info({data: {from: 'me', to: 'you'}}, 'data transfer');
Bunyan will generate
`json`
{
"name": "src-example", // the name configured for the log
"level": 30, // info is level:30
"msg": "data transfer", // your message
"data": {"from": "me", "to": "you"}, // your log data
"time": "2012-02-06T04:19:35.605Z",
"src": {
// only if use src: true while creating the logger
"file": "/Users/trentm/tm/node-bunyan/examples/src.js",
"line": 20,
"func": "Wuzzle.woos"
},
"hostname": "banana.local",
"pid": 123,
"v": 0
}
To make stackdriver-fluentd compatible it will be transformed into:
`json`
{
"name": "src-example",
"severity": 200, // map level into stackdriver severity
"message": "data transfer", // change msg to message
"data": {"from": "me", "to": "you"}, // your log data
"time": "2012-02-06T04:19:35.605Z",
"src": {
// only if use src: true while creating the logger
"file": "/Users/trentm/tm/node-bunyan/examples/src.js",
"line": 20,
"func": "Wuzzle.woos"
}
// erase not important keys v, pid, hostname
}
when logging an error with bunyan:
`jsError
log.info(err); // Special case to log an instance to the record.`
// This adds an "err" field with exception details
// (including the stack) and sets "msg" to the exception
// message.
log.info(err, 'more on this: %s', more);
// ... or you can specify the "msg".
Bunyan by default, will keep your error in err key. We will use the err.stack and set itmessage
as the , since that what's required by stackdriver.
Also, the error log entry for stackdriver requires us to set:
`ts`
"serviceContext": {
"service": string, // Required.
"version": string
},
We will use the name configured as serviceContext.name`.
Thanks to this, you can track your error ocurrences in https://cloud.google.com/error-reporting/
You can bypass fluentd & docker all together and log directly by calling the stackdriver API. I'm
not pro using a http transport for log within the applicaton, since every application will be
doing it's own buffering and sending, plus you will be loosing context information like the
node & pod id.
But, if that's not a proble, simply use https://github.com/googleapis/nodejs-logging-bunyan.