Bunyan is **a simple and fast JSON logging library** for node.js services: var bunyan = require('bunyan'); var log = bunyan.createLogger({name: "myapp"}); log.info("hi"); and **a `bunyan` CLI tool** for nicely viewing those logs: ![bunyan CLI screenshot](https://raw.github.com/trentm/node-bunyan/master/tools/screenshot1.png) Manifesto: Server logs should be structured. JSON's a good format. Let's do that. A log record is one line of `JSON.stringify`'d output. Let's also specify some common names for the requisite and common fields for a log record (see below). Also: log4j is way more than you need. # Current Status Solid core functionality is there. Joyent is using this for a number of production services. Bunyan supports node 0.6 and greater. Follow @trentmick for updates to Bunyan. There is an email discussion list [bunyan-logging@googlegroups.com](mailto:bunyan-logging@googlegroups.com), also [as a forum in the browser](https://groups.google.com/forum/?fromgroups#!forum/bunyan-logging). # Installation npm install bunyan **Tip**: The `bunyan` CLI tool is written to be compatible (within reason) with all versions of Bunyan logs. Therefore you might want to `npm install -g bunyan` to get the bunyan CLI on your PATH, then use local bunyan installs for node.js library usage of bunyan in your apps. To use the DTrace features (on platforms that support dtrace) you need to manually install the dtrace-provider library separately: npm install dtrace-provider Yes, this sucks. This used to be in "optionalDependencies" but [this](https://github.com/trentm/node-bunyan/issues/135) and other issues showed burden and confusion for users. I'm looking forward to coming *core* tracing facilities in node 0.12 to which bunyan can switch. # Features - elegant [log method API](#log-method-api) - extensible [streams](#streams) system for controlling where log records go (to a stream, to a file, [log file rotation](#stream-type-rotating-file), etc.) - [`bunyan` CLI](#cli-usage) for pretty-printing and filtering of Bunyan logs - simple include of log call source location (file, line, function) with [`src: true`](#src) - lightweight specialization of Logger instances with [`log.child`](#logchild) - custom rendering of logged objects with ["serializers"](#serializers) - [Runtime log snooping via Dtrace support](#runtime-log-snooping-via-dtrace) - Support for [browserify](http://browserify.org/). See [Browserify section](#browserify) below. # Introduction Like most logging libraries you create a Logger instance and call methods named after the logging levels: $ cat hi.js var bunyan = require('bunyan'); var log = bunyan.createLogger({name: 'myapp'}); log.info('hi'); log.warn({lang: 'fr'}, 'au revoir'); All loggers must provide a "name". This is somewhat akin to the log4j logger "name", but Bunyan doesn't do hierarchical logger names. **Bunyan log records are JSON.** A few fields are added automatically: "pid", "hostname", "time" and "v". $ node hi.js {"name":"myapp","hostname":"banana.local","pid":40161,"level":30,"msg":"hi","time":"2013-01-04T18:46:23.851Z","v":0} {"name":"myapp","hostname":"banana.local","pid":40161,"level":40,"lang":"fr","msg":"au revoir","time":"2013-01-04T18:46:23.853Z","v":0} ## Log Method API The example above shows two different ways to call `log.info(...)`. The full API is: log.info(); // Returns a boolean: is the "info" level enabled? // This is equivalent to `log.isInfoEnabled()` or // `log.isEnabledFor(INFO)` in log4j. log.info('hi'); // Log a simple string message (or number). log.info('hi %s', bob, anotherVar); // Uses `util.format` for msg formatting. log.info({foo: 'bar'}, 'hi'); // Adds "foo" field to log record. You can add any number // of additional fields here. log.info(err); // Special case to log an `Error` 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". Note that this implies **you cannot pass any object as the first argument to log it**. IOW, `log.info(mywidget)` may not be what you expect. Instead of a string representation of `mywidget` that other logging libraries may give you, Bunyan will try to JSON-ify your object. It is a Bunyan best practice to always give a field name to included objects, e.g.: log.info({widget: mywidget}, ...) This will dove-tail with [Bunyan serializer support](#serializers), discussed later. The same goes for all of Bunyan's log levels: `log.trace`, `log.debug`, `log.info`, `log.warn`, `log.error`, and `log.fatal`. See the [levels section](#levels) below for details and suggestions. ## CLI Usage Bunyan log output is a stream of JSON objects. This is great for processing, but not for reading directly. A **`bunyan` tool** is provided **for pretty-printing bunyan logs** and for **filtering** (e.g. `| bunyan -c 'this.foo == "bar"'`). Using our example above: $ node hi.js | ./bin/bunyan [2013-01-04T19:01:18.241Z] INFO: myapp/40208 on banana.local: hi [2013-01-04T19:01:18.242Z] WARN: myapp/40208 on banana.local: au revoir (lang=fr) See the screenshot above for an example of the default coloring of rendered log output. That example also shows the nice formatting automatically done for some well-known log record fields (e.g. `req` is formatted like an HTTP request, `res` like an HTTP response, `err` like an error stack trace). One interesting feature is **filtering** of log content, which can be useful for digging through large log files or for analysis. We can filter only records above a certain level: $ node hi.js | bunyan -l warn [2013-01-04T19:08:37.182Z] WARN: myapp/40353 on banana.local: au revoir (lang=fr) Or filter on the JSON fields in the records (e.g. only showing the French records in our contrived example): $ node hi.js | bunyan -c 'this.lang == "fr"' [2013-01-04T19:08:26.411Z] WARN: myapp/40342 on banana.local: au revoir (lang=fr) See `bunyan --help` for other facilities. ## Streams Introduction By default, log output is to stdout and at the "info" level. Explicitly that looks like: var log = bunyan.createLogger({ name: 'myapp', stream: process.stdout, level: 'info' }); That is an abbreviated form for a single stream. **You can define multiple streams at different levels**. var log = bunyan.createLogger({ name: 'myapp', streams: [ { level: 'info', stream: process.stdout // log INFO and above to stdout }, { level: 'error', path: '/var/log/myapp-error.log' // log ERROR and above to a file } ] }); More on streams in the [Streams section](#streams) below. ## log.child Bunyan has a concept of a child logger to **specialize a logger for a sub-component of your application**, i.e. to create a new logger with additional bound fields that will be included in its log records. A child logger is created with `log.child(...)`. In the following example, logging on a "Wuzzle" instance's `this.log` will be exactly as on the parent logger with the addition of the `widget_type` field: var bunyan = require('bunyan'); var log = bunyan.createLogger({name: 'myapp'}); function Wuzzle(options) { this.log = options.log.child({widget_type: 'wuzzle'}); this.log.info('creating a wuzzle') } Wuzzle.prototype.woos = function () { this.log.warn('This wuzzle is woosey.') } log.info('start'); var wuzzle = new Wuzzle({log: log}); wuzzle.woos(); log.info('done'); Running that looks like (raw): $ node myapp.js {"name":"myapp","hostname":"myhost","pid":34572,"level":30,"msg":"start","time":"2013-01-04T07:47:25.814Z","v":0} {"name":"myapp","hostname":"myhost","pid":34572,"widget_type":"wuzzle","level":30,"msg":"creating a wuzzle","time":"2013-01-04T07:47:25.815Z","v":0} {"name":"myapp","hostname":"myhost","pid":34572,"widget_type":"wuzzle","level":40,"msg":"This wuzzle is woosey.","time":"2013-01-04T07:47:25.815Z","v":0} {"name":"myapp","hostname":"myhost","pid":34572,"level":30,"msg":"done","time":"2013-01-04T07:47:25.816Z","v":0} And with the `bunyan` CLI (using the "short" output mode): $ node myapp.js | bunyan -o short 07:46:42.707Z INFO myapp: start 07:46:42.709Z INFO myapp: creating a wuzzle (widget_type=wuzzle) 07:46:42.709Z WARN myapp: This wuzzle is woosey. (widget_type=wuzzle) 07:46:42.709Z INFO myapp: done A more practical example is in the [node-restify](https://github.com/mcavage/node-restify) web framework. Restify uses Bunyan for its logging. One feature of its integration, is that if `server.use(restify.requestLogger())` is used, each restify request handler includes a `req.log` logger that is: log.child({req_id: }, true) Apps using restify can then use `req.log` and have all such log records include the unique request id (as "req\_id"). Handy. ## Serializers Bunyan has a concept of **"serializers" to produce a JSON-able object from a JavaScript object**, so you can easily do the following: log.info({req: }, 'something about handling this request'); Serializers is a mapping of log record field name, "req" in this example, to a serializer function. That looks like this: function reqSerializer(req) { return { method: req.method, url: req.url, headers: req.headers } } var log = bunyan.createLogger({ name: 'myapp', serializers: { req: reqSerializer } }); Or this: var log = bunyan.createLogger({ name: 'myapp', serializers: {req: bunyan.stdSerializers.req} }); because Buyan includes a small set of standard serializers. To use all the standard serializers you can use: var log = bunyan.createLogger({ ... serializers: bunyan.stdSerializers }); **Note**: Your own serializers should never throw, otherwise you'll get an ugly message on stderr from Bunyan (along with the traceback) and the field in your log record will be replaced with a short error message. ## src The **source file, line and function of the log call site** can be added to log records by using the `src: true` config option: var log = bunyan.createLogger({src: true, ...}); This adds the call source info with the 'src' field, like this: { "name": "src-example", "hostname": "banana.local", "pid": 123, "component": "wuzzle", "level": 4, "msg": "This wuzzle is woosey.", "time": "2012-02-06T04:19:35.605Z", "src": { "file": "/Users/trentm/tm/node-bunyan/examples/src.js", "line": 20, "func": "Wuzzle.woos" }, "v": 0 } **WARNING: Determining the call source info is slow. Never use this option in production.** # Levels The log levels in bunyan are as follows. The level descriptions are best practice *opinions*. - "fatal" (60): The service/app is going to stop or become unusable now. An operator should definitely look into this soon. - "error" (50): Fatal for a particular request, but the service/app continues servicing other requests. An operator should look at this soon(ish). - "warn" (40): A note on something that should probably be looked at by an operator eventually. - "info" (30): Detail on regular operation. - "debug" (20): Anything else, i.e. too verbose to be included in "info" level. - "trace" (10): Logging from external libraries used by your app or *very* detailed application logging. Suggestions: Use "debug" sparingly. Information that will be useful to debug errors *post mortem* should usually be included in "info" messages if it's generally relevant or else with the corresponding "error" event. Don't rely on spewing mostly irrelevant debug messages all the time and sifting through them when an error occurs. Integers are used for the actual level values (10 for "trace", ..., 60 for "fatal") and constants are defined for the (bunyan.TRACE ... bunyan.DEBUG). The lowercase level names are aliases supported in the API. Here is the API for changing levels in an existing logger: log.level() -> INFO // gets current level (lowest level of all streams) log.level(INFO) // set all streams to level INFO log.level("info") // set all streams to level INFO log.levels() -> [DEBUG, INFO] // get array of levels of all streams log.levels(0) -> DEBUG // get level of stream at index 0 log.levels("foo") // get level of stream with name "foo" log.levels(0, INFO) // set level of stream 0 to INFO log.levels(0, "info") // can use "info" et al aliases log.levels("foo", WARN) // set stream named "foo" to WARN # Log Record Fields This section will describe *rules* for the Bunyan log format: field names, field meanings, required fields, etc. However, a Bunyan library doesn't strictly enforce all these rules while records are being emitted. For example, Bunyan will add a `time` field with the correct format to your log records, but you can specify your own. It is the caller's responsibility to specify the appropriate format. The reason for the above leniency is because IMO logging a message should never break your app. This leads to this rule of logging: **a thrown exception from `log.info(...)` or equivalent (other than for calling with the incorrect signature) is always a bug in Bunyan.** A typical Bunyan log record looks like this: {"name":"myserver","hostname":"banana.local","pid":123,"req":{"method":"GET","url":"/path?q=1#anchor","headers":{"x-hi":"Mom","connection":"close"}},"level":3,"msg":"start request","time":"2012-02-03T19:02:46.178Z","v":0} Pretty-printed: { "name": "myserver", "hostname": "banana.local", "pid": 123, "req": { "method": "GET", "url": "/path?q=1#anchor", "headers": { "x-hi": "Mom", "connection": "close" }, "remoteAddress": "120.0.0.1", "remotePort": 51244 }, "level": 3, "msg": "start request", "time": "2012-02-03T19:02:57.534Z", "v": 0 } Core fields: - `v`: Required. Integer. Added by Bunyan. Cannot be overriden. This is the Bunyan log format version (`require('bunyan').LOG_VERSION`). The log version is a single integer. `0` is until I release a version "1.0.0" of node-bunyan. Thereafter, starting with `1`, this will be incremented if there is any backward incompatible change to the log record format. Details will be in "CHANGES.md" (the change log). - `level`: Required. Integer. Added by Bunyan. Cannot be overriden. See the "Levels" section. - `name`: Required. String. Provided at Logger creation. You must specify a name for your logger when creating it. Typically this is the name of the service/app using Bunyan for logging. - `hostname`: Required. String. Provided or determined at Logger creation. You can specify your hostname at Logger creation or it will be retrieved vi `os.hostname()`. - `pid`: Required. Integer. Filled in automatically at Logger creation. - `time`: Required. String. Added by Bunyan. Can be overriden. The date and time of the event in [ISO 8601 Extended Format](http://en.wikipedia.org/wiki/ISO_8601) format and in UTC, as from [`Date.toISOString()`](https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Date/toISOString). - `msg`: Required. String. Every `log.debug(...)` et al call must provide a log message. - `src`: Optional. Object giving log call source info. This is added automatically by Bunyan if the "src: true" config option is given to the Logger. Never use in production as this is really slow. Go ahead and add more fields, and nested ones are fine (and recommended) as well. This is why we're using JSON. Some suggestions and best practices follow (feedback from actual users welcome). Recommended/Best Practice Fields: - `err`: Object. A caught JS exception. Log that thing with `log.info(err)` to get: ... "err": { "message": "boom", "name": "TypeError", "stack": "TypeError: boom\n at Object. ..." }, "msg": "boom", ... Or use the `bunyan.stdSerializers.err` serializer in your Logger and do this `log.error({err: err}, "oops")`. See "examples/err.js". - `req_id`: String. A request identifier. Including this field in all logging tied to handling a particular request to your server is strongly suggested. This allows post analysis of logs to easily collate all related logging for a request. This really shines when you have a SOA with multiple services and you carry a single request ID from the top API down through all APIs (as [node-restify](https://github.com/mcavage/node-restify) facilitates with its 'Request-Id' header). - `req`: An HTTP server request. Bunyan provides `bunyan.stdSerializers.req` to serialize a request with a suggested set of keys. Example: { "method": "GET", "url": "/path?q=1#anchor", "headers": { "x-hi": "Mom", "connection": "close" }, "remoteAddress": "120.0.0.1", "remotePort": 51244 } - `res`: An HTTP server response. Bunyan provides `bunyan.stdSerializers.res` to serialize a response with a suggested set of keys. Example: { "statusCode": 200, "header": "HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\nConnection: keep-alive\r\nTransfer-Encoding: chunked\r\n\r\n" } Other fields to consider: - `req.username`: Authenticated user (or for a 401, the user attempting to auth). - Some mechanism to calculate response latency. "restify" users will have a "X-Response-Time" header. A `latency` custom field would be fine. - `req.body`: If you know that request bodies are small (common in APIs, for example), then logging the request body is good. # Streams A "stream" is Bunyan's name for an output for log messages (the equivalent to a log4j Appender). Ultimately Bunyan uses a [Writable Stream](http://nodejs.org/docs/latest/api/all.html#writable_Stream) interface, but there are some additional attributes used to create and manage the stream. A Bunyan Logger instance has one or more streams. In general streams are specified with the "streams" option: var bunyan = require('bunyan'); var log = bunyan.createLogger({ name: "foo", streams: [ { stream: process.stderr, level: "debug" }, ... ] }); For convenience, if there is only one stream, it can specified with the "stream" and "level" options (internally converted to a `Logger.streams`). var log = bunyan.createLogger({ name: "foo", stream: process.stderr, level: "debug" }); Note that "file" streams do not support this shortcut (partly for historical reasons and partly to not make it difficult to add a literal "path" field on log records). If neither "streams" nor "stream" are specified, the default is a stream of type "stream" emitting to `process.stdout` at the "info" level. ## stream errors Bunyan re-emits error events from the created `WriteStream`. So you can do this: var log = bunyan.createLogger({name: 'mylog', streams: [{path: LOG_PATH}]}); log.on('error', function (err, stream) { // Handle stream write or create error here. }); Note: This is **not** that same as a log record at the "error" level as produced by `log.error(...)`. ## stream type: `stream` A `type === 'stream'` is a plain ol' node.js [Writable Stream](http://nodejs.org/docs/latest/api/all.html#writable_Stream). A "stream" (the writeable stream) field is required. E.g.: `process.stdout`, `process.stderr`. var log = bunyan.createLogger({ name: 'foo', streams: [{ stream: process.stderr // `type: 'stream'` is implied }] });
Field Required? Default Description
stream Yes - A "Writable Stream", e.g. a std handle or an open file write stream.
type No n/a `type == 'stream'` is implied if the `stream` field is given.
level No info The level at which logging to this stream is enabled. If not specified it defaults to "info". If specified this can be one of the level strings ("trace", "debug", ...) or constants (`bunyan.TRACE`, `bunyan.DEBUG`, ...).
name No - A name for this stream. This may be useful for usage of `log.level(NAME, LEVEL)`. See the [Levels section](#levels) for details. A stream "name" isn't used for anything else.
## stream type: `file` A `type === 'file'` stream requires a "path" field. Bunyan will open this file for appending. E.g.: var log = bunyan.createLogger({ name: 'foo', streams: [{ path: '/var/log/foo.log', // `type: 'file'` is implied }] });
Field Required? Default Description
path Yes - A file path to which to log.
type No n/a `type == 'file'` is implied if the `path` field is given.
level No info The level at which logging to this stream is enabled. If not specified it defaults to "info". If specified this can be one of the level strings ("trace", "debug", ...) or constants (`bunyan.TRACE`, `bunyan.DEBUG`, ...).
name No - A name for this stream. This may be useful for usage of `log.level(NAME, LEVEL)`. See the [Levels section](#levels) for details. A stream "name" isn't used for anything else.
## stream type: `rotating-file` **WARNING on node 0.8 usage:** Users of Bunyan's `rotating-file` should (a) be using at least bunyan 0.23.1 (with the fix for [this issue](https://github.com/trentm/node-bunyan/pull/97)), and (b) should use at least node 0.10 (node 0.8 does not support the `unref()` method on `setTimeout(...)` needed for the mentioned fix). The symptom is that process termination will hang for up to a full rotation period. **WARNING on [cluster](http://nodejs.org/docs/latest/api/all.html#all_cluster) usage:** Using Bunyan's `rotating-file` stream with node.js's "cluster" module can result in unexpected file rotation. You must not have multiple processes in the cluster logging to the same file path. In other words, you must have a separate log file path for the master and each worker in the cluster. Alternatively, consider using a system file rotation facility such as `logrotate` on Linux or `logadm` on SmartOS/Illumos. See [this comment on issue #117](https://github.com/trentm/node-bunyan/issues/117#issuecomment-44804938) for details. A `type === 'rotating-file'` is a file stream that handles file automatic rotation. var log = bunyan.createLogger({ name: 'foo', streams: [{ type: 'rotating-file', path: '/var/log/foo.log', period: '1d', // daily rotation count: 3 // keep 3 back copies }] }); This will rotate '/var/log/foo.log' every day (at midnight) to: /var/log/foo.log.0 # yesterday /var/log/foo.log.1 # 1 day ago /var/log/foo.log.2 # 2 days ago *Currently*, there is no support for providing a template for the rotated files, or for rotating when the log reaches a threshold size.
Field Required? Default Description
type Yes - "rotating-file"
path Yes - A file path to which to log. Rotated files will be "$path.0", "$path.1", ...
period No 1d The period at which to rotate. This is a string of the format "$number$scope" where "$scope" is one of "h" (hours), "d" (days), "w" (weeks), "m" (months), "y" (years). Or one of the following names can be used "hourly" (means 1h), "daily" (1d), "weekly" (1w), "monthly" (1m), "yearly" (1y). Rotation is done at the start of the scope: top of the hour (h), midnight (d), start of Sunday (w), start of the 1st of the month (m), start of Jan 1st (y).
count No 10 The number of rotated files to keep.
level No info The level at which logging to this stream is enabled. If not specified it defaults to "info". If specified this can be one of the level strings ("trace", "debug", ...) or constants (`bunyan.TRACE`, `bunyan.DEBUG`, ...).
name No - A name for this stream. This may be useful for usage of `log.level(NAME, LEVEL)`. See the [Levels section](#levels) for details. A stream "name" isn't used for anything else.
**Note on log rotation**: Often you may be using external log rotation utilities like `logrotate` on Linux or `logadm` on SmartOS/Illumos. In those cases, unless your are ensuring "copy and truncate" sematics (via `copytruncate` with logrotate or `-c` with logadm) then the fd for your 'file' stream will change. You can tell bunyan to reopen the file stream with code like this in your app: var log = bunyan.createLogger(...); ... process.on('SIGUSR2', function () { log.reopenFileStreams(); }); where you'd configure your log rotation to send SIGUSR2 (or some other signal) to your process. Any other mechanism to signal your app to run `log.reopenFileStreams()` would work as well. ## stream type: `raw` - `raw`: Similar to a "stream" writeable stream, except that the write method is given raw log record *Object*s instead of a JSON-stringified string. This can be useful for hooking on further processing to all Bunyan logging: pushing to an external service, a RingBuffer (see below), etc. ## `raw` + RingBuffer Stream Bunyan comes with a special stream called a RingBuffer which keeps the last N records in memory and does *not* write the data anywhere else. One common strategy is to log 'info' and higher to a normal log file but log all records (including 'trace') to a ringbuffer that you can access via a debugger, or your own HTTP interface, or a post-mortem facility like MDB or node-panic. To use a RingBuffer: /* Create a ring buffer that stores the last 100 records. */ var bunyan = require('bunyan'); var ringbuffer = new bunyan.RingBuffer({ limit: 100 }); var log = bunyan.createLogger({ name: 'foo', streams: [ { level: 'info', stream: process.stdout }, { level: 'trace', type: 'raw', // use 'raw' to get raw log record objects stream: ringbuffer } ] }); log.info('hello world'); console.log(ringbuffer.records); This example emits: [ { name: 'foo', hostname: '912d2b29', pid: 50346, level: 30, msg: 'hello world', time: '2012-06-19T21:34:19.906Z', v: 0 } ] ## third-party streams - syslog: [mcavage/node-bunyan-syslog](https://github.com/mcavage/node-bunyan-syslog) provides support for directing bunyan logging to a syslog server. - TODO: eventually https://github.com/trentm/node-bunyan-winston # Runtime log snooping via DTrace **Note**: To use Bunyan's DTrace facilities you need to manually install the "dtrace-provider" lib separately via `npm install dtrace-provider`. On systems that support DTrace (e.g., MacOS, FreeBSD, illumos derivatives like SmartOS and OmniOS), Bunyan will create a DTrace provider (`bunyan`) that makes available the following probes: log-trace log-debug log-info log-warn log-error log-fatal Each of these probes has a single argument: the string that would be written to the log. Note that when a probe is enabled, it will fire whenever the corresponding function is called, even if the level of the log message is less than that of any stream. ## DTrace examples Trace all log messages coming from any Bunyan module on the system. (The `-x strsize=4k` is to raise dtrace's default 256 byte buffer size because log messages are longer than typical dtrace probes.) dtrace -x strsize=4k -qn 'bunyan*:::log-*{printf("%d: %s: %s", pid, probefunc, copyinstr(arg0))}' Trace all log messages coming from the "wuzzle" component: dtrace -x strsize=4k -qn 'bunyan*:::log-*/strstr(this->str = copyinstr(arg0), "\"component\":\"wuzzle\"") != NULL/{printf("%s", this->str)}' Aggregate debug messages from process 1234, by message: dtrace -x strsize=4k -n 'bunyan1234:::log-debug{@[copyinstr(arg0)] = count()}' Have the bunyan CLI pretty-print the traced logs: dtrace -x strsize=4k -qn 'bunyan1234:::log-*{printf("%s", copyinstr(arg0))}' | bunyan A convenience handle has been made for this: bunyan -p 1234 On systems that support the [`jstack`](http://dtrace.org/blogs/dap/2012/04/25/profiling-node-js/) action via a node.js helper, get a stack backtrace for any debug message that includes the string "danger!": dtrace -x strsize=4k -qn 'log-debug/strstr(copyinstr(arg0), "danger!") != NULL/{printf("\n%s", copyinstr(arg0)); jstack()}' Output of the above might be: {"name":"foo","hostname":"763bf293-d65c-42d5-872b-4abe25d5c4c7.local","pid":12747,"level":20,"msg":"danger!","time":"2012-10-30T18:28:57.115Z","v":0} node`0x87e2010 DTraceProviderBindings.node`usdt_fire_probe+0x32 DTraceProviderBindings.node`_ZN4node11DTraceProbe5_fireEN2v85LocalINS1_5ValueEEE+0x32d DTraceProviderBindings.node`_ZN4node11DTraceProbe4FireERKN2v89ArgumentsE+0x77 << internal code >> (anon) as (anon) at /root/node-bunyan/lib/bunyan.js position 40484 << adaptor >> (anon) as doit at /root/my-prog.js position 360 (anon) as list.ontimeout at timers.js position 4960 << adaptor >> << internal >> << entry >> node`_ZN2v88internalL6InvokeEbNS0_6HandleINS0_10JSFunctionEEENS1_INS0_6ObjectEEEiPS5_Pb+0x101 node`_ZN2v88internal9Execution4CallENS0_6HandleINS0_6ObjectEEES4_iPS4_Pbb+0xcb node`_ZN2v88Function4CallENS_6HandleINS_6ObjectEEEiPNS1_INS_5ValueEEE+0xf0 node`_ZN4node12MakeCallbackEN2v86HandleINS0_6ObjectEEENS1_INS0_8FunctionEEEiPNS1_INS0_5ValueEEE+0x11f node`_ZN4node12MakeCallbackEN2v86HandleINS0_6ObjectEEENS1_INS0_6StringEEEiPNS1_INS0_5ValueEEE+0x66 node`_ZN4node9TimerWrap9OnTimeoutEP10uv_timer_si+0x63 node`uv__run_timers+0x66 node`uv__run+0x1b node`uv_run+0x17 node`_ZN4node5StartEiPPc+0x1d0 node`main+0x1b node`_start+0x83 node`0x87e2010 DTraceProviderBindings.node`usdt_fire_probe+0x32 DTraceProviderBindings.node`_ZN4node11DTraceProbe5_fireEN2v85LocalINS1_5ValueEEE+0x32d DTraceProviderBindings.node`_ZN4node11DTraceProbe4FireERKN2v89ArgumentsE+0x77 << internal code >> (anon) as (anon) at /root/node-bunyan/lib/bunyan.js position 40484 << adaptor >> (anon) as doit at /root/my-prog.js position 360 (anon) as list.ontimeout at timers.js position 4960 << adaptor >> << internal >> << entry >> node`_ZN2v88internalL6InvokeEbNS0_6HandleINS0_10JSFunctionEEENS1_INS0_6ObjectEEEiPS5_Pb+0x101 node`_ZN2v88internal9Execution4CallENS0_6HandleINS0_6ObjectEEES4_iPS4_Pbb+0xcb node`_ZN2v88Function4CallENS_6HandleINS_6ObjectEEEiPNS1_INS_5ValueEEE+0xf0 node`_ZN4node12MakeCallbackEN2v86HandleINS0_6ObjectEEENS1_INS0_8FunctionEEEiPNS1_INS0_5ValueEEE+0x11f node`_ZN4node12MakeCallbackEN2v86HandleINS0_6ObjectEEENS1_INS0_6StringEEEiPNS1_INS0_5ValueEEE+0x66 node`_ZN4node9TimerWrap9OnTimeoutEP10uv_timer_si+0x63 node`uv__run_timers+0x66 node`uv__run+0x1b node`uv_run+0x17 node`_ZN4node5StartEiPPc+0x1d0 node`main+0x1b node`_start+0x83 # Browserify As the [Browserify](http://browserify.org/) site says it "lets you `require('modules')` in the browser by bundling up all of your dependencies." It is a build tool to run on your node.js script to bundle up your script and all its node.js dependencies into a single file that is runnable in the browser via: As of version 1.1.0, node-bunyan supports being run via Browserify. The default [stream](#streams) when running in the browser is one that emits raw log records to `console.log/info/warn/error`. Here is a quick example showing you how you can get this working for your script. 1. Get browserify and bunyan installed in your module: $ npm install browserify bunyan 2. An example script using Bunyan, "play.js": ```javascript var bunyan = require('bunyan'); var log = bunyan.createLogger({name: 'play', level: 'debug'}); log.trace('this one does not emit'); log.debug('hi on debug'); // console.log log.info('hi on info'); // console.info log.warn('hi on warn'); // console.warn log.error('hi on error'); // console.error ``` 3. Build this into a bundle to run in the browser, "play.browser.js": $ ./node_modules/.bin/browserify play.js -o play.browser.js 4. Put that into an HTML file, "play.html": ```html
hi
``` 5. Open that in your browser and open your browser console: $ open play.html Here is what it looks like in Firefox's console: ![Bunyan + Browserify in the Firefox console](./docs/img/bunyan.browserify.png) For some, the raw log records might not be desired. To have a rendered log line you'll want to add your own stream, starting with something like this: ```javascript function MyRawStream() {} MyRawStream.prototype.write = function (rec) { var nameFromLevel = { TRACE: 'TRACE' DEBUG: 'DEBUG', INFO: 'INFO', WARN: 'WARN', ERROR: 'ERROR', FATAL: 'FATAL' }; console.log('[%s] %s: %s', rec.time, nameFromLevel[rec.level], rec.msg); } var log = bunyan.createLogger({ name: 'play', streams: [ { level: 'info', stream: new MyRawStream(), type: 'raw' }, ] }); log.info('hi on info'); ``` # Versioning The scheme I follow is most succintly described by the bootstrap guys [here](https://github.com/twitter/bootstrap#versioning). tl;dr: All versions are `..` which will be incremented for breaking backward compat and major reworks, new features without breaking change, and bug fixes, respectively. # License MIT. See "LICENSE.txt". # See Also - Bunyan syslog support: . - Bunyan + Graylog2: . - Bunyan middleware for Express: - An example of a Bunyan shim to the Winston logging system: . Also a [comparison of Winston and Bunyan](http://strongloop.com/strongblog/compare-node-js-logging-winston-bunyan/). - [Bunyan for Bash](https://github.com/trevoro/bash-bunyan). - TODO: `RequestCaptureStream` example from restify. - [Bunyan integration for https://logentries.com](https://www.npmjs.org/package/logentries-stream)