bunyan on npm

1.8.12 (02 Aug 2017 23:08)

a JSON logging library for node.js services


bunyan Changelog

Known issues:

not yet released

(nothing yet)

2.0.2 (beta)

  • [issue #444] Fix the bunyan CLI to not duplicate the "HTTP/1.1 ..." status line when serializing a "res" field.

2.0.1 (beta)

  • [issue #504] Backward incompatible change to the bunyan CLI: The bunyan CLI no longer adds a Host header when rendering a client_req field in a log record. In 1.x it used to do this (using client_req.address and client_req.port), on the guess that Node.js' http.ClientRequest handling would add it. However, the guess can be wrong and misleading. It is better not to guess.

2.0.0 (beta)

  • [issue #499] Fix some bunyan CLI exit handling problems.


  • Ensure that bunyan errors out if attempting to use -p PID and file args at the same time.


  • [pull #409, issue #246] Revert a change added to the bunyan CLI version 1.0.1 where SIGINT was ignored, such that Ctrl+C could not be used to terminate bunyan. (By @zbjornson and @davepacheco.)
  • [pull #469] Fix a strict mode ("use strict;") error in some versions of Safari.


  • Fix breakage due to a silly last minute "fix 'make check'".


Note: Bad release. Use 1.8.8 or later.

  • [issue #484] Fix breakage due to #474 in previous release.


Note: Bad release. Use 1.8.7 or later.

  • [issue #474] Bunyan's safeCycles is too slow when logging large objects.


  • [issue #401] Improved performance when using disabled log levels.


  • [issue #454] Fix src usage with node v7.


  • [issue #450] Fix log.info(null) crash that resulted from #426 in v1.8.2.


  • [issue #449] Bump dtrace-provider dep to 0.7.0 to help avoid deprecation warnings with node v6 in some cases.
  • [issue #426] Ensure log.info({err: err}) results in a "msg" value, just like log.info(err).


  • [pull #386] Fix bad bug in rotation that could cause a crash with error message "cannot start a rotation when already rotating" (by Frankie O'Rourke). The bug was introduced in 1.8.0.


Note: Bad release. An addition in this release broke 'rotating-file' usage. Use 1.8.1 or later.

  • [issue #370] Fix bunyan -p ... (i.e. DTrace integration) on node 4.x and 5.x.
  • [issue #329, pull #330] Update the 'rotating-file' stream to do a file rotation on initialization if the mtime on the file path indicates the last rotation time was missed -- i.e. if the app wasn't running at the time. (by Paul Milham.)


  • [issue #332, pull #355] Ensure stream for type='stream' stream is a writable stream. (By Michael Nisi.)

  • [issue #344] Fix "rotating-file" Bunyan streams to not miss rotations when configured for a period greater than approximately 25 days. Before this there was an issue where periods greater than node.js's maximum setTimeout length would fail to rotate. (By Martijn Schrage.)

  • [issue #234, pull #345] Improve bunyan CLI rendering of "res" field HTTP responses to not show two blank lines for an empty body. (By Michael Nisi.)


  • [pull #311, #302, #310] Improve the runtime environment detection to fix running under NW.js. Contributions by Adam Lynch, Jeremy Ruppel, and Aleksey Timchenko.

  • [pull #318] Add reemitErrorEvents optional boolean for streams added to a Bunyan logger to control whether an "error" event on the stream will be re-emitted on the Logger instance.

      var log = bunyan.createLogger({
          name: 'foo',
          streams: [
                  type: 'raw',
                  stream: new MyCustomStream(),
                  reemitErrorEvents: true

    Before this change, "error" events were re-emitted on file streams only. The new behaviour is as follows:

    • reemitErrorEvents not specified: file streams will re-emit error events on the Logger instance.
    • reemitErrorEvents: true: error events will be re-emitted on the Logger for any stream with a .on() function -- which includes file streams, process.stdout/stderr, and any object that inherits from EventEmitter.
    • reemitErrorEvents: false: error events will not be re-emitted for any streams.

    Dev Note: Bunyan Logger objects don't currently have a .close() method in which registered error event handlers can be unregistered. That means that a (presumably rare) situation where code adds dozens of Bunyan Logger streams to, e.g. process.stdout, and with reemitErrorEvents: true, could result in leaking Logger objects.

    Original work for allowing "error" re-emitting on non-file streams is by Marc Udoff in pull #318.


  • [pull #304, issue #245] Use [Moment.js][momentjs.com] library to handle bunyan CLI time formatting in some cases, especially to fix display of local time. It is now required for local time formatting (i.e. bunyan -L or bunyan --time local). (By David M. Lee.)

  • [pull #252] Fix errant client_res={} in bunyan CLI rendering, and avoid extra newlines in client_req rendering in some cases. (By Thomas Heymann.)

  • [pull #291, issue #303] Fix LOG.child(...) to not override the "hostname" field of the parent. A use case is when one manually sets "hostname" to something other than os.hostname(). (By github.com/Cactusbone.)

  • [issue #325] Allow one to set level: 0 in createLogger to turn on logging for all levels. (Adapted from #336 by github.com/sometimesalready.)

  • Add guards (to resolveLevel) so that all "level" values are validated. Before this, a bogus level like "foo" or -12 or ['some', 'array'] would silently be accepted -- with undefined results.

  • Doc updates for #340 and #305.

  • Update make test to test against node 5, 4, 0.12 and 0.10.


  • [issue #296] Fix src: true, which was broken in v1.5.0.


Note: Bad release. The addition of 'use strict'; broke Bunyan's src: true feature. Use 1.5.1 instead.

  • [pull #236, issue #231, issue #223] Fix strict mode in the browser.
  • [pull #282, issue #213] Fixes bunyan to work with webpack. By Denis Izmaylov.
  • [pull #294] Update to dtrace-provider 0.6 to fix with node 4.0 and io.js 3.0.
  • Dropped support for 0.8 (can't install deps easily anymore for running test suite). Bump to a recent iojs version for testing.


(Bumping minor ver b/c I'm wary of dtrace-provider changes. :)

  • [issue #258, pull #259] Update to dtrace-provider 0.5 to fix install and tests on recent io.js versions.
  • safe-json-stringify@1.0.3 changed output, breaking some tests. Fix those.


  • [issue #244] Make bunyan defensive on res.header=null.


  • [issue #233] Make bunyan defensive on res.header as a boolean.
  • [issue #242] Make bunyan defensive on err.stack not being a string.


  • Allow log.child(...) to work even if the logger is a sub-class of Bunyan's Logger class.
  • [issue #219] Hide 'source-map-support' require from browserify.
  • [issue #218] Reset haveNonRawStreams on <logger>.addStream.


  • [pull #127] Update to dtrace-provider 0.4.0, which gives io.js 1.x support for dtrace-y parts of Bunyan.


  • [pull #182] Fallback to using the optional 'safe-json-stringify' module if JSON.stringify throws -- possibly with an enumerable property getter than throws. By Martin Gausby.


  • Export bunyan.RotatingFileStream which is needed if one wants to customize it. E.g. see issue #194.

  • [pull #122] Source Map support for caller line position for the "src" field. This could be interesting for CoffeeScript users of Bunyan. By Manuel Schneider.

  • [issue #164] Ensure a top-level level given in bunyan.createLogger is used for given streams. For example, ensure that the following results in the stream having a DEBUG level:

      var log = bunyan.createLogger({
          name: 'foo',
          level: 'debug',
          streams: [
                  path: '/var/tmp/foo.log'

    This was broken in the 1.0.1 release. Between that release and 1.3.0 the "/var/tmp/foo.log" stream would be at the INFO level (Bunyan's default level).


  • [issue #103] bunyan -L (or bunyan --time local) to show local time. Bunyan log records store time in UTC time. Sometimes it is convenient to display in local time.

  • [issue #205] Fix the "The Bunyan CLI crashed!" checking to properly warn of the common failure case when -c CONDITION is being used.


  • [issue #210] Export bunyan.nameFromLevel and bunyan.levelFromName. It can be a pain for custom streams to have to reproduce that.

  • [issue #100] Gracefully handle the case of an unbound Logger.{info,debug,...} being used for logging, e.g.:

      myEmittingThing.on('data', log.info)

    Before this change, bunyan would throw. Now it emits a warning to stderr once, and then silently ignores those log attempts, e.g.:

      bunyan usage error: /Users/trentm/tm/node-bunyan/foo.js:12: attempt to log with an unbound log method: `this` is: { _events: { data: [Function] } }



  • Drop the guard that a bunyan Logger level must be between TRACE (10) and FATAL (60), inclusive. This allows a trick of setting the level to FATAL + 1 to turn logging off. While the standard named log levels are the golden path, then intention was not to get in the way of using other level numbers.


  • [issue #178, #181] Get at least dtrace-provider 0.3.1 for optionalDependencies to get a fix for install with decoupled npm (e.g. with homebrew's node and npm).


  • [issue #157] Restore dtrace-provider as a dependency (in "optionalDependencies").

    Dtrace-provider version 0.3.0 add build sugar that should eliminate the problems from older versions: The build is not attempted on Linux and Windows. The build spew is not emitted by default (use V=1 npm install to see it); instead a short warning is emitted if the build fails.

    Also, importantly, the new dtrace-provider fixes working with node v0.11/0.12.


  • [issue #165] Include extra err fields in bunyan CLI output. Before this change only the fields part of the typical node.js error stack (err.stack, err.message, err.name) would be emitted, even though the Bunyan library would typically include err.code and err.signal in the raw JSON log record.


  • Fix a breakage in log.info(err) on a logger with no serializers.


Note: Bad release. It breaks log.info(err) on a logger with no serializers. Use version 1.1.2.

  • [pull #168] Fix handling of log.info(err) to use the log Logger's err serializer if it has one, instead of always using the core Bunyan err serializer. (By Mihai Tomescu.)



  • [issues #105, #138, #151] Export <Logger>.addStream(...) and <Logger>.addSerializers(...) to be able to add them after Logger creation. Thanks @andreineculau!

  • [issue #159] Fix bad handling in construtor guard intending to allow creation without "new": var log = Logger(...). Thanks @rmg!

  • [issue #156] Smaller install size via .npmignore file.

  • [issue #126, #161] Ignore SIGINT (Ctrl+C) when processing stdin. ...| bunyan should expect the preceding process in the pipeline to handle SIGINT. While it is doing so, bunyan should continue to process any remaining output. Thanks @timborodin and @jnordberg!

  • [issue #160] Stop using ANSI 'grey' in bunyan CLI output, because of the problems that causes with Solarized Dark themes (see https://github.com/altercation/solarized/issues/220).


  • [issue #87] Backward incompatible change to -c CODE improving performance by over 10x (good!), with a backward incompatible change to semantics (unfortunate), and adding some sugar (good!).

    The -c CODE implementation was changed to use a JS function for processing rather than vm.runInNewContext. The latter was specatularly slow, so won't be missed. Unfortunately this does mean a few semantic differences in the CODE, the most noticeable of which is that this is required to access the object fields:

      # Bad. Works with bunyan 0.x but not 1.x.
      $ bunyan -c 'pid === 123' foo.log
      # Good. Works with all versions of bunyan
      $ bunyan -c 'this.pid === 123' foo.log

    The old behaviour of -c can be restored with the BUNYAN_EXEC=vm environment variable:

      $ BUNYAN_EXEC=vm bunyan -c 'pid === 123' foo.log

    Some sugar was also added: the TRACE, DEBUG, ... constants are defined, so one can:

      $ bunyan -c 'this.level >= ERROR && this.component === "http"' foo.log

    And example of the speed improvement on a 10 MiB log example:

      $ time BUNYAN_EXEC=vm bunyan -c 'this.level === ERROR' big.log | cat >slow
      real    0m6.349s
      user    0m6.292s
      sys    0m0.110s
      $ time bunyan -c 'this.level === ERROR' big.log | cat >fast
      real    0m0.333s
      user    0m0.303s
      sys    0m0.028s

    The change was courtesy Patrick Mooney (https://github.com/pfmooney). Thanks!

  • Add bunyan -0 ... shortcut for bunyan -o bunyan ....

  • [issue #135] Backward incompatible. Drop dtrace-provider even from optionalDependencies. Dtrace-provider has proven a consistent barrier to installing bunyan, because it is a binary dep. Even as an optional dep it still caused confusion and install noise.

    Users of Bunyan on dtrace-y platforms (SmartOS, Mac, Illumos, Solaris) will need to manually npm install dtrace-provider themselves to get Bunyan's dtrace support to work. If not installed, bunyan should stub it out properly.


  • [pull #125, pull #97, issue #73] Unref rotating-file timeout which was preventing processes from exiting (by https://github.com/chakrit and https://github.com/glenn-murray-bse). Note: this only fixes the issue for node 0.10 and above.


  • [issue #139] Fix bunyan crash on a log record with res.header that is an object. A side effect of this improvement is that a record with res.statusCode but no header info will render a response block, for example:

      [2012-08-08T10:25:47.637Z]  INFO: my-service/12859 on my-host: some message (...)
          HTTP/1.1 200 OK
  • [pull #42] Fix bunyan crash on a log record with req.headers that is a string (by https://github.com/aexmachina).

  • Drop node 0.6 support. I can't effectively npm install with a node 0.6 anymore.

  • [issue #85] Ensure logging a non-object/non-string doesn't throw (by https://github.com/mhart). This changes fixes:

      log.info(<bool>)     # TypeError: Object.keys called on non-object
      log.info(<function>) # "msg":"" (instead of wanted "msg":"[Function]")
      log.info(<array>)    # "msg":"" (instead of wanted "msg":util.format(<array>))


  • Republish the same code to npm.


Note: Bad release. The published package in the npm registry got corrupted. Use 0.22.3 or later.

  • [issue #131] Allow log.info(<number>) and, most importantly, don't crash on that.

  • Update 'mv' optional dep to latest.


  • [issue #111] Fix a crash when attempting to use bunyan -p on a platform without dtrace.

  • [issue #101] Fix a crash in bunyan rendering a record with unexpected "res.headers".


  • [issue #104] log.reopenFileStreams() convenience method to be used with external log rotation.


  • [issue #96] Fix bunyan to default to paging (with less) by default in node 0.10.0. The intention has always been to default to paging for node >=0.8.


  • [issue #90] Fix bunyan -p '*' breakage in version 0.21.2.


Note: Bad release. The switchrate change below broke bunyan -p '*' usage (see issue #90). Use 0.21.3 or later.

  • [issue #88] Should be able to efficiently combine "-l" with "-p *".

  • Avoid DTrace buffer filling up, e.g. like this:

      $ bunyan -p 42241 > /tmp/all.log
      dtrace: error on enabled probe ID 3 (ID 75795: bunyan42241:mod-87ea640:log-trace:log-trace): out of scratch space in action #1 at DIF offset 12
      dtrace: error on enabled probe ID 3 (ID 75795: bunyan42241:mod-87ea640:log-trace:log-trace): out of scratch space in action #1 at DIF offset 12
      dtrace: 138 drops on CPU 4

    From Bryan: "the DTrace buffer is filling up because the string size is so large... by increasing the switchrate, you're increasing the rate at which that buffer is emptied."


  • [pull #83] Support rendering 'client_res' key in bunyan CLI (by github.com/mcavage).


  • 'make check' clean, 4-space indenting. No functional change here, just lots of code change.
  • [issue #80, #82] Drop assert that broke using 'rotating-file' with a default period (by github.com/ricardograca).


  • [Slight backward incompatibility] Fix serializer bug introduced in 0.18.3 (see below) to only apply serializers to log records when appropriate.

    This also makes a semantic change to custom serializers. Before this change a serializer function was called for a log record key when that value was truth-y. The semantic change is to call the serializer function as long as the value is not undefined. That means that a serializer function should handle falsey values such as false and null.

  • Update to latest 'mv' dep (required for rotating-file support) to support node v0.10.0.


WARNING: This release includes a bug introduced in bunyan 0.18.3 (see below). Please upgrade to bunyan 0.20.0.

  • [Slight backward incompatibility] Change the default error serialization (a.k.a. bunyan.stdSerializers.err) to not serialize all additional attributes of the given error object. This is an open door to unsafe logging and logging should always be safe. With this change, error serialization will log these attributes: message, name, stack, code, signal. The latter two are added because some core node APIs include those fields (e.g. child_process.exec).

    Concrete examples where this has hurt have been the "domain" change necessitating 0.18.3 and a case where node-restify uses an error object as the response object. When logging the err and res in the same log statement (common for restify audit logging), the res.body would be JSON stringified as '[Circular]' as it had already been emitted for the err key. This results in a WTF with the bunyan CLI because the err.body is not rendered.

    If you need the old behaviour back you will need to do this:

      var bunyan = require('bunyan');
      var errSkips = {
          // Skip domain keys. `domain` especially can have huge objects that can
          // OOM your app when trying to JSON.stringify.
          domain: true,
          domain_emitter: true,
          domain_bound: true,
          domain_thrown: true
      bunyan.stdSerializers.err = function err(err) {
         if (!err || !err.stack)
             return err;
         var obj = {
             message: err.message,
             name: err.name,
             stack: getFullErrorStack(err)
         Object.keys(err).forEach(function (k) {
             if (err[k] !== undefined && !errSkips[k]) {
                 obj[k] = err[k];
         return obj;
  • "long" and "bunyan" output formats for the CLI. bunyan -o long is the default format, the same as before, just called "long" now instead of the cheesy "paul" name. The "bunyan" output format is the same as "json-0", just with a more convenient name.


WARNING: This release introduced a bug such that all serializers are applied to all log records even if the log record did not contain the key for that serializer. If a logger serializer function does not handle being given undefined, then you'll get warnings like this on stderr:

bunyan: ERROR: This should never happen. This is a bug in <https://github.com/trentm/node-bunyan> or in this application. Exception from "foo" Logger serializer: Error: ...
    at Object.bunyan.createLogger.serializers.foo (.../myapp.js:20:15)
    at Logger._applySerializers (.../lib/bunyan.js:644:46)
    at Array.forEach (native)
    at Logger._applySerializers (.../lib/bunyan.js:640:33)

and the following junk in written log records:

"foo":"(Error in Bunyan log "foo" serializer broke field. See stderr for details.)"

Please upgrade to bunyan 0.20.0.

  • Change the bunyan.stdSerializers.err serializer for errors to exclude the "domain*" keys. err.domain will include its assigned members which can arbitrarily large objects that are not intended for logging.

  • Make the "dtrace-provider" dependency optional. I hate to do this, but installing bunyan on Windows is made very difficult with this as a required dep. Even though "dtrace-provider" stubs out for non-dtrace-y platforms, without a compiler and Python around, node-gyp just falls over.


  • [pull #67] Remove debugging prints in rotating-file support. (by github.com/chad3814).
  • Update to dtrace-provider@0.2.7.


  • Get the bunyan CLI to not automatically page (i.e. pipe to less) if stdin isn't a TTY, or if following dtrace probe output (via -p PID), or if not given log file arguments.


  • Automatic paging support in the bunyan CLI (similar to git log et al). IOW, bunyan will open your pager (by default less) and pipe rendered log output through it. A main benefit of this is getting colored logs with a pager without the pain. Before you had to explicit use --color to tell bunyan to color output when the output was not a TTY:

      bunyan foo.log --color | less -R        # before
      bunyan foo.log                          # now

    Disable with the --no-pager option or the BUNYAN_NO_PAGER=1 environment variable.

    Limitations: Only supported for node >=0.8. Windows is not supported (at least not yet).

  • Switch test suite to nodeunit (still using a node-tap'ish API via a helper).


  • [issue #33] Log rotation support:

      var bunyan = require('bunyan');
      var log = bunyan.createLogger({
          name: 'myapp',
          streams: [{
              type: 'rotating-file',
              path: '/var/log/myapp.log',
              count: 7,
              period: 'daily'
  • Tweak to CLI default pretty output: don't special case "latency" field. The special casing was perhaps nice, but less self-explanatory. Before:

      [2012-12-27T21:17:38.218Z]  INFO: audit/45769 on myserver: handled: 200 (15ms, audit=true, bar=baz)
        GET /foo


      [2012-12-27T21:17:38.218Z]  INFO: audit/45769 on myserver: handled: 200 (audit=true, bar=baz, latency=15)
        GET /foo
  • Exit CLI on EPIPE, otherwise we sit there useless processing a huge log file with, e.g. bunyan huge.log | head.


  • Guards on -c CONDITION usage to attempt to be more user friendly. Bogus JS code will result in this:

      $ bunyan portal.log -c 'this.req.username==boo@foo'
      bunyan: error: illegal CONDITION code: SyntaxError: Unexpected token ILLEGAL
        CONDITION script:
          Object.prototype.TRACE = 10;
          Object.prototype.DEBUG = 20;
          Object.prototype.INFO = 30;
          Object.prototype.WARN = 40;
          Object.prototype.ERROR = 50;
          Object.prototype.FATAL = 60;
          SyntaxError: Unexpected token ILLEGAL
              at new Script (vm.js:32:12)
              at Function.Script.createScript (vm.js:48:10)
              at parseArgv (/Users/trentm/tm/node-bunyan-0.x/bin/bunyan:465:27)
              at main (/Users/trentm/tm/node-bunyan-0.x/bin/bunyan:1252:16)
              at Object.<anonymous> (/Users/trentm/tm/node-bunyan-0.x/bin/bunyan:1330:3)
              at Module._compile (module.js:449:26)
              at Object.Module._extensions..js (module.js:467:10)
              at Module.load (module.js:356:32)
              at Function.Module._load (module.js:312:12)
              at Module.runMain (module.js:492:10)

    And all CONDITION scripts will be run against a minimal valid Bunyan log record to ensure they properly guard against undefined values (at least as much as can reasonably be checked). For example:

      $ bunyan portal.log -c 'this.req.username=="bob"'
      bunyan: error: CONDITION code cannot safely filter a minimal Bunyan log record
        CONDITION script:
          Object.prototype.TRACE = 10;
          Object.prototype.DEBUG = 20;
          Object.prototype.INFO = 30;
          Object.prototype.WARN = 40;
          Object.prototype.ERROR = 50;
          Object.prototype.FATAL = 60;
        Minimal Bunyan log record:
            "v": 0,
            "level": 30,
            "name": "name",
            "hostname": "hostname",
            "pid": 123,
            "time": 1355514346206,
            "msg": "msg"
        Filter error:
          TypeError: Cannot read property 'username' of undefined
              at bunyan-condition-0:7:9
              at Script.Object.keys.forEach.(anonymous function) [as runInNewContext] (vm.js:41:22)
              at parseArgv (/Users/trentm/tm/node-bunyan-0.x/bin/bunyan:477:18)
              at main (/Users/trentm/tm/node-bunyan-0.x/bin/bunyan:1252:16)
              at Object.<anonymous> (/Users/trentm/tm/node-bunyan-0.x/bin/bunyan:1330:3)
              at Module._compile (module.js:449:26)
              at Object.Module._extensions..js (module.js:467:10)
              at Module.load (module.js:356:32)
              at Function.Module._load (module.js:312:12)
              at Module.runMain (module.js:492:10)

    A proper way to do that condition would be:

      $ bunyan portal.log -c 'this.req && this.req.username=="bob"'


  • [issue #59] Clear a possibly interrupted ANSI color code on signal termination.


  • [issue #56] Support bunyan -p NAME to dtrace all PIDs matching 'NAME' in their command and args (using ps -A -o pid,command | grep NAME or, on SunOS pgrep -lf NAME). E.g.:

      bunyan -p myappname

    This is useful for usage of node's cluster module where you'll have multiple worker processes.


  • Allow bunyan -p '*' to capture bunyan dtrace probes from all processes.
  • issue #55: Add support for BUNYAN_NO_COLOR environment variable to turn off all output coloring. This is still overridden by the --color and --no-color options.


  • issue #54: Ensure (again, see 0.16.2) that stderr from the dtrace child process (when using bunyan -p PID) gets through. There had been a race between exiting bunyan and the flushing of the dtrace process' stderr.



  • Ensure that stderr from the dtrace child process (when using bunyan -p PID) gets through. The pipe usage wasn't working on SmartOS. This is important to show the user if they need to 'sudo'.


  • Ensure that a possible dtrace child process (with using bunyan -p PID) is terminated on signal termination of the bunyan CLI (at least for SIGINT, SIGQUIT, SIGTERM, SIGHUP).


  • Add bunyan -p PID support. This is a convenience wrapper that effectively calls:

      dtrace -x strsize=4k -qn 'bunyan$PID:::log-*{printf("%s", copyinstr(arg0))}' | bunyan


  • issue #48: Dtrace support! The elevator pitch is you can watch all logging from all Bunyan-using process with something like this:

      dtrace -x strsize=4k -qn 'bunyan*:::log-*{printf("%d: %s: %s", pid, probefunc, copyinstr(arg0))}'

    And this can include log levels below what the service is actually configured to log. E.g. if the service is only logging at INFO level and you need to see DEBUG log messages, with this you can. Obviously this only works on dtrace-y platforms: Illumos derivatives of SunOS (e.g. SmartOS, OmniOS), Mac, FreeBSD.

    Or get the bunyan CLI to render logs nicely:

      dtrace -x strsize=4k -qn 'bunyan*:::log-*{printf("%s", copyinstr(arg0))}' | bunyan

    See https://github.com/trentm/node-bunyan#dtrace-support for details. By Bryan Cantrill.


  • Export bunyan.safeCycles(). This may be useful for custom type == "raw" streams that may do JSON stringification of log records themselves. Usage:

      var str = JSON.stringify(rec, bunyan.safeCycles());
  • [issue #49] Allow a log.child() to specify the level of inherited streams. For example:

      # Before
      var childLog = log.child({...});
      # After
      var childLog = log.child({..., level: 'debug'});
  • Improve the Bunyan CLI crash message to make it easier to provide relevant details in a bug report.


  • Fix a bug in the long-stack-trace error serialization added in 0.14.4. The symptom:

      bunyan@0.14.4: .../node_modules/bunyan/lib/bunyan.js:1002
        var ret = ex.stack || ex.toString();
      TypeError: Cannot read property 'stack' of undefined
          at getFullErrorStack (.../node_modules/bunyan/lib/bunyan.js:1002:15)


  • Bad release. Use 0.14.5 instead.

  • Improve error serialization to walk the chain of .cause() errors from the likes of WError or VError error classes from verror and restify v2.0. Example:

      [2012-10-11T00:30:21.871Z] ERROR: imgapi/99612 on 0525989e-2086-4270-b960-41dd661ebd7d: my-message
          ValidationFailedError: my-message; caused by TypeError: cause-error-message
              at Server.apiPing (/opt/smartdc/imgapi/lib/app.js:45:23)
              at next (/opt/smartdc/imgapi/node_modules/restify/lib/server.js:550:50)
              at Server.setupReq (/opt/smartdc/imgapi/lib/app.js:178:9)
              at next (/opt/smartdc/imgapi/node_modules/restify/lib/server.js:550:50)
              at Server.parseBody (/opt/smartdc/imgapi/node_modules/restify/lib/plugins/body_parser.js:15:33)
              at next (/opt/smartdc/imgapi/node_modules/restify/lib/server.js:550:50)
              at Server.parseQueryString (/opt/smartdc/imgapi/node_modules/restify/lib/plugins/query.js:40:25)
              at next (/opt/smartdc/imgapi/node_modules/restify/lib/server.js:550:50)
              at Server._run (/opt/smartdc/imgapi/node_modules/restify/lib/server.js:579:17)
              at Server._handle.log.trace.req (/opt/smartdc/imgapi/node_modules/restify/lib/server.js:480:38)
          Caused by: TypeError: cause-error-message
              at Server.apiPing (/opt/smartdc/imgapi/lib/app.js:40:25)
              at next (/opt/smartdc/imgapi/node_modules/restify/lib/server.js:550:50)
              at Server.setupReq (/opt/smartdc/imgapi/lib/app.js:178:9)
              at next (/opt/smartdc/imgapi/node_modules/restify/lib/server.js:550:50)
              at Server.parseBody (/opt/smartdc/imgapi/node_modules/restify/lib/plugins/body_parser.js:15:33)
              at next (/opt/smartdc/imgapi/node_modules/restify/lib/server.js:550:50)
              at Server.parseQueryString (/opt/smartdc/imgapi/node_modules/restify/lib/plugins/query.js:40:25)
              at next (/opt/smartdc/imgapi/node_modules/restify/lib/server.js:550:50)
              at Server._run (/opt/smartdc/imgapi/node_modules/restify/lib/server.js:579:17)
              at Server._handle.log.trace.req (/opt/smartdc/imgapi/node_modules/restify/lib/server.js:480:38)


  • [issue #45] Fix bunyan CLI (default output mode) to not crash on a 'res' field that isn't a response object, but a string.


  • [issue #44] Fix the default bunyan CLI output of a res.body that is an object instead of a string. See issue#38 for the same with req.body.


  • [pull #41] Safe JSON.stringifying of emitted log records to avoid blowing up on circular objects (by Isaac Schlueter).


  • [issue #39] Fix a bug with client_req handling in the default output of the bunyan CLI.


  • [issue #38] Fix the default bunyan CLI output of a req.body that is an object instead of a string.


  • Export bunyan.resolveLevel(NAME-OR-NUM) to resolve a level name or number to its log level number value:

      > bunyan.resolveLevel('INFO')
      > bunyan.resolveLevel('debug')

    A side-effect of this change is that the uppercase level name is now allowed in the logger constructor.


  • [issue #35] Ensure that an accidental log.info(BUFFER), where BUFFER is a node.js Buffer object, doesn't blow up.


  • [issue #34] Ensure req.body, res.body and other request/response fields are emitted by the bunyan CLI (mostly by Rob Gulewich).


  • [issue #31] Re-instate defines for the (uppercase) log level names (TRACE, DEBUG, etc.) in bunyan -c "..." filtering condition code. E.g.:

      $ ... | bunyan -c 'level >= ERROR'


  • [pull #32] bunyan -o short for more concise output (by Dave Pacheco). E.g.:

      22:56:52.856Z  INFO myservice: My message

    instead of:

      [2012-02-08T22:56:52.856Z]  INFO: myservice/123 on example.com: My message


  • Add '--strict' option to bunyan CLI to suppress all but legal Bunyan JSON log lines. By default non-JSON, and non-Bunyan lines are passed through.


  • [issue #30] Robust handling of 'req' field without a 'headers' subfield in bunyan CLI.
  • [issue #31] Pull the TRACE, DEBUG, et al defines from bunyan -c "..." filtering code. This was added in v0.11.1, but has a significant adverse affect.


  • Bad release. The TRACE et al names are bleeding into the log records when using '-c'.

  • Add defines for the (uppercase) log level names (TRACE, DEBUG, etc.) in bunyan -c "..." filtering condition code. E.g.:

      $ ... | bunyan -c 'level >= ERROR'


  • [pull #29] Add -l/--level for level filtering, and -c/--condition for arbitrary conditional filtering (by github.com/isaacs):

      $ ... | bunyan -l error   # filter out log records below error
      $ ... | bunyan -l 50      # numeric value works too
      $ ... | bunyan -c 'level===50'              # equiv with -c filtering
      $ ... | bunyan -c 'pid===123'               # filter on any field
      $ ... | bunyan -c 'pid===123' -c '_audit'   # multiple filters


  • [pull #24] Support for gzip'ed log files in the bunyan CLI (by github.com/mhart):

      $ bunyan foo.log.gz


  • [pull #16] Bullet proof the bunyan.stdSerializers (by github.com/rlidwka).

  • [pull #15] The bunyan CLI will now chronologically merge multiple log streams when it is given multiple file arguments. (by github.com/davepacheco)

      $ bunyan foo.log bar.log
      ... merged log records ...
  • [pull #15] A new bunyan.RingBuffer stream class that is useful for keeping the last N log messages in memory. This can be a fast way to keep recent, and thus hopefully relevant, log messages. (by @dapsays, github.com/davepacheco)

    Potential uses: Live debugging if a running process could inspect those messages. One could dump recent log messages at a finer log level than is typically logged on uncaughtException.

      var ringbuffer = new bunyan.RingBuffer({ limit: 100 });
      var log = new bunyan({
          name: 'foo',
          streams: [{
              type: 'raw',
              stream: ringbuffer,
              level: 'debug'
      log.info('hello world');
  • Add support for "raw" streams. This is a logging stream that is given raw log record objects instead of a JSON-stringified string.

      function Collector() {
          this.records = [];
      Collector.prototype.write = function (rec) {
      var log = new Logger({
          name: 'mylog',
          streams: [{
              type: 'raw',
              stream: new Collector()

    See "examples/raw-stream.js". I expect raw streams to be useful for piping Bunyan logging to separate services (e.g. http://www.loggly.com/, https://github.com/etsy/statsd) or to separate in-process handling.

  • Add test/corpus/*.log files (accidentally excluded) so the test suite actually works(!).


  • [pull #21] Bunyan loggers now re-emit fs.createWriteStream error events. By github.com/EvanOxfeld. See "examples/handle-fs-error.js" and "test/error-event.js" for details.

      var log = new Logger({name: 'mylog', streams: [{path: FILENAME}]});
      log.on('error', function (err, stream) {
          // Handle error writing to or creating FILENAME.
  • jsstyle'ing (via make check)


  • [issue #12] Add bunyan.createLogger(OPTIONS) form, as is more typical in node.js APIs. This'll eventually become the preferred form.


  • Change bunyan CLI default output to color "src" info red. Before the "src" information was uncolored. The "src" info is the filename, line number and function name resulting from using src: true in Logger creation. I.e., the (/Users/trentm/tm/node-bunyan/examples/hi.js:10) in:

      [2012-04-10T22:28:58.237Z]  INFO: myapp/39339 on banana.local (/Users/trentm/tm/node-bunyan/examples/hi.js:10): hi
  • Tweak bunyan CLI default output to still show an "err" field if it doesn't have a "stack" attribute.


  • Fix bad bug in log.child({...}, true); where the added child fields would be added to the parent's fields. This bug only existed for the "fast child" path (that second true argument). A side-effect of fixing this is that the "fast child" path is only 5 times as fast as the regular log.child, instead of 10 times faster.


  • [issue #6] Fix bleeding 'type' var to global namespace. (Thanks Mike!)


  • Add support to the bunyan CLI taking log file path args, bunyan foo.log, in addition to the usual cat foo.log | bunyan.
  • Improve reliability of the default output formatting of the bunyan CLI. Before it could blow up processing log records missing some expected fields.


  • ANSI coloring output from bunyan CLI tool (for the default output mode/style). Also add the '--color' option to force coloring if the output stream is not a TTY, e.g. cat my.log | bunyan --color | less -R. Use --no-color to disable coloring, e.g. if your terminal doesn't support ANSI codes.
  • Add 'level' field to log record before custom fields for that record. This just means that the raw record JSON will show the 'level' field earlier, which is a bit nicer for raw reading.


  • [issue #5] Fix log.info() -> boolean to work properly. Previous all were returning false. Ditto all trace/debug/.../fatal methods.


  • Allow an optional msg and arguments to the log.info(<Error> err) logging form. For example, before:

      log.debug(my_error_instance)            // good
      log.debug(my_error_instance, "boom!")   // wasn't allowed

    Now the latter is allowed if you want to expliciting set the log msg. Of course this applies to all the log.{trace|debug|info...}() methods.

  • bunyan cli output: clarify extra fields with quoting if empty or have spaces. E.g. 'cmd' and 'stderr' in the following:

      [2012-02-12T00:30:43.736Z] INFO: mo-docs/43194 on banana.local: buildDocs results (req_id=185edca2-2886-43dc-911c-fe41c09ec0f5, route=PutDocset, error=null, stderr="", cmd="make docs")



  • Internal: starting jsstyle usage.
  • Internal: add .npmignore. Previous packages had reams of bunyan crud in them.


  • Add 'pid' automatic log record field.


  • Add 'client_req' (HTTP client request) standard formatting in bunyan CLI default output.
  • Improve bunyan CLI default output to include all log record keys. Unknown keys are either included in the first line parenthetical (if short) or in the indented subsequent block (if long or multiline).


  • [issue #3] More type checking of new Logger(...) and log.child(...) options.
  • Start a test suite.


  • [issue #2] Add guard on JSON.stringifying of log records before emission. This will prevent log.info et al throwing on record fields that cannot be represented as JSON. An error will be printed on stderr and a clipped log record emitted with a 'bunyanMsg' key including error details. E.g.:

      bunyan: ERROR: could not stringify log record from /Users/trentm/tm/node-bunyan/examples/unstringifyable.js:12: TypeError: Converting circular structure to JSON
        "name": "foo",
        "hostname": "banana.local",
        "bunyanMsg": "bunyan: ERROR: could not stringify log record from /Users/trentm/tm/node-bunyan/examples/unstringifyable.js:12: TypeError: Converting circular structure to JSON",

    Some timing shows this does effect log speed:

      $ node tools/timeguard.js     # before
      Time try/catch-guard on JSON.stringify:
       - log.info:  0.07365ms per iteration
      $ node tools/timeguard.js     # after
      Time try/catch-guard on JSON.stringify:
       - log.info:  0.07368ms per iteration


  • Use 10/20/... instead of 1/2/... for level constant values. Ostensibly this allows for intermediary levels from the defined "trace/debug/..." set. However, that is discouraged. I'd need a strong user argument to add support for easily using alternative levels. Consider using a separate JSON field instead.

  • s/service/name/ for Logger name field. "service" is unnecessarily tied to usage for a service. No need to differ from log4j Logger "name".

  • Add log.level(...) and log.levels(...) API for changing logger stream levels.

  • Add TRACE|DEBUG|INFO|WARN|ERROR|FATAL level constants to exports.

  • Add log.info(err) special case for logging an Error instance. For example log.info(new TypeError("boom") will produce:

      "err": {
        "message": "boom",
        "name": "TypeError",
        "stack": "TypeError: boom\n    at Object.<anonymous> ..."
      "msg": "boom",


  • Add new Logger({src: true}) config option to have a 'src' attribute be automatically added to log records with the log call source info. Example:

      "src": {
        "file": "/Users/trentm/tm/node-bunyan/examples/src.js",
        "line": 20,
        "func": "Wuzzle.woos"


  • log.child(options[, simple]) Added simple boolean arg. Set true to assert that options only add fields (no config changes). Results in a 10x speed increase in child creation. See "tools/timechild.js". On my Mac, "fast child" creation takes about 0.001ms. IOW, if your app is dishing 10,000 req/s, then creating a log child for each request will take about 1% of the request time.
  • log.clone -> log.child to better reflect the relationship: streams and serializers are inherited. Streams can't be removed as part of the child creation. The child doesn't own the parent's streams (so can't close them).
  • Clean up Logger creation. The goal here was to ensure log.child usage is fast. TODO: measure that.
  • Add Logger.stdSerializers.err serializer which is necessary to get good Error object logging with node 0.6 (where core Error object properties are non-enumerable).


  • Spec'ing core/recommended log record fields.
  • Add LOG_VERSION to exports.
  • Improvements to request/response serializations.


First release.

Version History

Version Date
1.8.12 02 Aug 2017 23:08
2.0.2 02 Aug 2017 23:08
2.0.1 02 Aug 2017 20:08
1.8.11 02 Aug 2017 20:08
2.0.0 04 May 2017 06:05
1.8.10 05 Apr 2017 06:04
1.8.9 21 Mar 2017 05:03
1.8.8 03 Mar 2017 22:03
1.8.7 03 Mar 2017 21:03
1.8.6 03 Mar 2017 18:03
1.8.5 14 Nov 2016 18:11
1.8.4 25 Oct 2016 18:10
1.8.3 18 Oct 2016 20:10
1.8.2 17 Oct 2016 23:10
1.8.1 21 Apr 2016 08:04
1.8.0 17 Mar 2016 05:03
1.7.1 29 Feb 2016 06:02
1.7.0 22 Feb 2016 01:02
1.6.0 11 Feb 2016 06:02
1.5.1 07 Sep 2015 21:09
1.5.0 07 Sep 2015 08:09
1.4.0 07 Jun 2015 18:06
1.3.6 02 Jun 2015 05:06
1.3.5 13 Apr 2015 05:04
1.3.4 20 Feb 2015 22:02
1.3.3 26 Jan 2015 17:01
1.3.2 19 Jan 2015 07:01
1.3.1 18 Jan 2015 06:01
1.3.0 17 Jan 2015 21:01
1.2.4 16 Jan 2015 06:01
1.2.3 18 Nov 2014 05:11
1.2.2 14 Nov 2014 07:11
1.2.1 26 Oct 2014 04:10
1.2.0 17 Oct 2014 21:10
1.1.3 28 Sep 2014 04:09
1.1.2 28 Sep 2014 04:09
1.1.1 28 Sep 2014 04:09
1.1.0 22 Sep 2014 04:09
1.0.1 25 Aug 2014 07:08
1.0.0 01 Aug 2014 22:08
0.23.1 01 Jun 2014 05:06
0.23.0 31 May 2014 03:05
0.22.3 11 Apr 2014 00:04
0.22.2 10 Apr 2014 23:04
0.22.1 26 Nov 2013 07:11
0.22.0 11 Oct 2013 20:10
0.21.4 02 Jul 2013 23:07
0.21.3 22 May 2013 00:05
0.21.2 17 May 2013 09:05
0.21.1 05 Apr 2013 00:04
0.21.0 02 Apr 2013 04:04
0.20.0 15 Mar 2013 18:03
0.19.0 11 Mar 2013 22:03
0.18.3 02 Mar 2013 00:03
0.18.2 29 Jan 2013 07:01
0.18.1 23 Jan 2013 01:01
0.18.0 23 Jan 2013 00:01
0.17.0 04 Jan 2013 22:01
0.16.8 14 Dec 2012 19:12
0.16.7 15 Nov 2012 06:11
0.16.6 13 Nov 2012 08:11
0.16.5 06 Nov 2012 20:11
0.16.4 05 Nov 2012 06:11
0.16.3 02 Nov 2012 20:11
0.16.2 02 Nov 2012 20:11
0.16.1 02 Nov 2012 19:11
0.16.0 02 Nov 2012 06:11
0.15.0 01 Nov 2012 20:11
0.14.6 24 Oct 2012 17:10
0.14.5 11 Oct 2012 21:10
0.14.4 11 Oct 2012 00:10
0.14.3 11 Oct 2012 00:10
0.14.2 10 Oct 2012 18:10
0.14.1 09 Oct 2012 22:10
0.14.0 10 Sep 2012 19:09
0.13.5 30 Aug 2012 19:08
0.13.4 28 Aug 2012 17:08
0.13.3 24 Aug 2012 23:08
0.13.2 22 Aug 2012 22:08
0.13.1 21 Aug 2012 18:08
0.13.0 14 Aug 2012 03:08
0.12.0 13 Aug 2012 23:08
0.11.3 09 Aug 2012 16:08
0.11.2 09 Aug 2012 05:08
0.11.1 08 Aug 2012 18:08
0.11.0 08 Aug 2012 05:08
0.10.0 22 Jun 2012 05:06
0.9.0 22 Jun 2012 03:06
0.8.0 05 Jun 2012 06:06
0.7.0 27 Apr 2012 23:04
0.6.9 27 Apr 2012 23:04
0.6.8 28 Feb 2012 00:02
0.6.7 24 Feb 2012 20:02
0.6.6 24 Feb 2012 05:02
0.6.5 23 Feb 2012 21:02
0.6.4 20 Feb 2012 05:02
0.6.3 17 Feb 2012 00:02
0.6.2 11 Feb 2012 05:02
0.6.1 10 Feb 2012 08:02
0.6.0 10 Feb 2012 05:02
0.5.3 08 Feb 2012 23:02
0.5.2 08 Feb 2012 18:02
0.5.1 07 Feb 2012 05:02
0.5.0 06 Feb 2012 23:02
0.4.0 06 Feb 2012 04:02
0.3.0 05 Feb 2012 05:02
0.2.0 04 Feb 2012 01:02
0.1.0 02 Feb 2012 23:02