FiLog is a highly configurable isomorphic logger for Meteor applications, supporting configurable logging strategies and custom processing and log sending destinations.
Out of the box, it can log to the console (browser, server), the Meteor database, any Syslog server, and includes a "tee" logger to send to multiple destinations. On the browser, it can log to its own Meteor server over DDP, or to a centralized FiLog log aggregation server over HTTP.
FiLog is based upon low-level NPM packages::
- Stack capture and standardization: https://www.npmjs.com/package/tracekit
- Meteor user capture in call stack: https://www.npmjs.com/package/callsite
Read the Documentation.
- A logged event is a
(level, message, context)triplet, in whichlevelis an RFC5424 number (0..7)messageis a plain string or can be converted to one automaticallycontextis a plain Object
- the package has no configuration of its own, it is entirely configured by its users, the client- and server-side Meteor parts of the application.
- Both client and server applications may capture exception stack traces and log
them for plain errors (
window.onerrorhandling) and exception reporting. This is triggered by thelogger.arm()method, and can be disabled by thelogger.disarm()method.
client/main.js:-
instantiates any number of "processors": instances of classes derived from
ProcessorBase. These are able to add information to a message on its way to the logging destination. Current concrete processors are:BrowserProcessor: adds browser-related information, such as user agent, platform, operating system, client memoryMeteorUserProcessor: adds user-related information if any is available. Assumes the application is configured with some Meteor accounts package, likefgm:accounts-drupal.RoutingProcessor: adds request-related information, such as the path being served.
-
instantiates any number of "senders": instances of classes derived from
SenderBase. These are able to receive a(level, message, context)triplet ("event") and forward it somwhere else. Current concrete senders are:ConsoleSender: output the message usingconsole.logMeteorClientHttpSender: HTTP POST the message to the Meteor server present at the URL defined by the Meteor-standardROOT_URLenvironment variable.MongodbSender: store the event in a collection in the Meteor MongoDB database instance (or the minimongo on the client).NullSender: ignore the message.SyslogSender: send the event to syslog, on server only: including it on client will fail.TeeSender: send the event to all sender instances passed to its constructor as an array. Useful to send logs to multiple destinations.
-
instantiate a sending "strategy": instance of a class derived from
StrategyBase. There are able to decide, based on an event, where it should be sent by available senders. They may also modify the logger instance at the last step of its construction, Two concrete strategies are currently available:LeveledStrategy: based on the level of the message, it defines three severity levels: low, medium, and high, as well as the breakpoints between them in terms of RFC5424 levels, and associates a sender instance with each of these levelsTrivialStrategyuses a single sender for all messages. Especially useful for early work client-side, where you want everything to be stored to collect as much information as possible from a limited number of clients. May also be useful for tests, to simplify test setup.
-
constructs a
ClientLoggerinstance, passing it the strategy instance, like:let logger = new ClientLogger(new LeveledStrategy( new NullSender(), new ConsoleSender(), new MeteorClientHttpSender(Meteor.absoluteUrl('logger')) )); -
adds processor instances to the logger instance, like:
logger.processors.push( new BrowserProcessor(), new RoutingProcessor(), new MeteorUserProcessor(Meteor) ); -
is now able to log events, like:
logger.warn("Some warning condition", { foo: "bar" }); -
with this configuration:
- logger applies processors to add browser, user, and routing information to the message context
- since warnings are considered worthy of storage (default configuration
of the
LeveledStrategyconstructor), the logger passes the now-rich message to the Meteor server thanks to theMeteorClientHttpSendersender - message arrives server-side.
-
server/main.js-
is configured in much the same way as the client, so it has its own
logger, typically configured with just aMongodbSenderinstance for all levels.let sender = new MongodbSender(Mongo, 'logger'); let logger = new ServerLogger( new LeveledStrategy(sender, sender, sender), WebApp); logger.processors.push(new MeteorUserProcessor()); -
in the example above, it receives the POSTed event, and proceed to log it
- because it has already been processed client-side, it is logged "raw", without applying additional processors to it
- the MongoDb sender instance stores the event.
-
the server may also initiate a logging action, for example in a publish function or Meteor method. It can use the same API:
logger.error("Some server condition", { baz: "quux" }- since the message is server-originated, the server processors will be applied, to add the Meteor user information to the event
- the MongoDb sender instance stores the event.
-
- Whatever the enabled processors, the
Logger.log()method adds a millisecond-level timestamp to each context, under thetimestamp.logkey. - Senders designed to exit the system, like the MongoDB sender, or a syslog or
logstash Beats forwarder, are expected to add another millisecond-level
timestamp, under the
timestamp.storekey.
These two timestamps are here to alleviate any issue resulting from a clock difference between clients and servers.
Any sender can add extra keys to the context, under the timestamp main key,
to enable timing diagnostics.
The module contains tests. Some of them are unit tests and need nothing special
to run, while others are currently implemented as integration tests and assume
you have a working harness project using Filog, exposed on
http://localhost:3000.
Start by compiling the package:
meteor yarn run ts-compile
Then you can run :
- just unit tests with
meteor yarn run test-unit - just integration tests with
meteor yarn run test-integration - both tests with
meteor yarn run test - both tests including coverage generation with
meteor yarn run cover
To run integration tests, you need to run the provided test_harness project in one terminal, and the tests in another one. Alternatively, you could also roll your own bespoke test harness, which will need to have Filog configured.
This file is needed to allow Filog to operate on the /logger URL: otherwise,
Meteor will handle it natively and return a 200 with the default application
page, failing the integration tests.
cd (filog_dir)/test_harness
meteor yarn
meteor run --port 3100This example uses port 3100 to avoid conflicting with existing applications on
the default Meteor port (3000). To use another port, be sure to change it in
__tests__/integration/harness.ts too.
cd (filog_dir)
meteor yarn
meteor yarn run compile
meteor yarn run test
meteor yarn run coverTIP Reading the .travis.yml file can be useful too.
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