New Relic Node.js agent

This package instruments your application for performance monitoring with New Relic.

This is a beta release. You should probably try it in your staging or development environment first. If you would prefer to wait for the GA release, please sign up to be notified.

Make sure you have a New Relic account before starting. To see all the features, such as slow transaction traces, you will need a New Relic Pro subscription. Contact your New Relic representative to request a Pro Trial subscription during your beta testing.

Getting started

Install node. For now, at least 0.6 is required. Some features (e.g. error tracing) depend in whole or in part on features in 0.8 and above. Development work on the agent is being done against the latest released non-development version of Node.
Install this module via npm install newrelic for the application you want to monitor.
Copy newrelic.js from node_modules/newrelic into the root directory of your application.
Edit newrelic.js and replace license_key's value with the license key for your account.
Add require('newrelic'); as the first line of the app's main module. IMPORTANT: formerly this was require('newrelic_agent'), and you MUST update your code.

If you wish to keep the configuration for the agent separate from your application, the agent will look for newrelic.js in the directory referenced by the environment variable NEW_RELIC_HOME if it's set.

When you start your app, the agent should start up with it and start reporting data that will appear within the New Relic UI after a few minutes. Because the agent minimizes the amount of bandwidth it consumes, it only reports data once a minute, so if you add the agent to tests that take less than a minute to run, the agent won't have time to report data to New Relic. The agent will write its log to a file named newrelic_agent.log in the application directory. If the agent doesn't send data or crashes your app, the log can help New Relic determine what went wrong, so be sure to send it along with any bug reports or support requests.

Configuring the agent

The agent can be tailored to your app's requirements, both from the server and via the newrelic.js configuration file you created. For more details on what can be configured, refer to lib/config.default.js, which documents the available variables and their default values.

In addition, for those of you running in Heroku, Microsoft Azure or any other PaaS environment that makes it easier to control configuration via the your server's environment, all of the configuration variables in newrelic.js have counterparts that can be set in your service's shell environment. You can mix and match the configuration file and environment variables freely; the value found from the environment will always take precedence.

This documentation will be moving to New Relic's servers with the 1.0 release, but for now, here's a list of the variables and their values:

NEW_RELIC_HOME: path to the directory in which you've placed newrelic.js.
NEW_RELIC_APP_NAME: The name of this application, for reporting to New Relic's servers. This value can be also be a comma-delimited list of names.
NEW_RELIC_ENABLED: Whether or not the agent should run. Good for temporarily disabling the agent while debugging other issues with your code.
NEW_RELIC_NO_CONFIG_FILE: Inhibit loading of the configuration file altogether. Use with care. This presumes that all important configuration will be available via environment variables, and some log messages assume that a config file exists.
NEW_RELIC_LICENSE_KEY: Your New Relic license key.
NEW_RELIC_LOG: Complete path to the New Relic agent log, including the filename. The agent will shut down the process if it can't create this file, and it creates the log file with the same umask of the process. Setting this to stdout will write all logging to stdout, and stderr will write all logging to stderr.
NEW_RELIC_LOG_LEVEL: Logging priority for the New Relic agent. Can be one of error, warn, info, debug, or trace. debug and trace are pretty chatty; unless you're helping New Relic figure out irregularities with the agent, you're probably best off using info or higher.
NEW_RELIC_ERROR_COLLECTOR_ENABLED: Whether or not to trace errors within your application. Values are true or false.
NEW_RELIC_ERROR_COLLECTOR_IGNORE_ERROR_CODES: Comma-delimited list of HTTP status codes to ignore. Maybe you don't care if payment is required?
NEW_RELIC_TRACER_ENABLED: Whether to collect and submit slow transaction traces to New Relic. Values are true or false.
NEW_RELIC_TRACER_THRESHOLD: Millisecond duration at which a transaction trace will count as slow and be sent to New Relic. Can also be set to apdex_f, at which point it will set the trace threshold to 4 times the current ApdexT.
NEW_RELIC_TRACER_TOP_N: Number of transaction traces to send to New Relic on each 60-second harvest cycle. Defaults to 1. This can lead to noisy transaction traces and should be used with care.
NEW_RELIC_APDEX: Set the initial Apdex tolerating / threshold value. This is more often than not set from the server.
NEW_RELIC_HOST: Hostname for the New Relic collector proxy. You shouldn't need to change this.
NEW_RELIC_PORT: Port number on which the New Relic collector proxy will be listening.
NEW_RELIC_DEBUG_METRICS: Whether to collect internal supportability metrics for the agent. Don't mess with this unless New Relic asks you to.
NEW_RELIC_DEBUG_TRACER: Whether to dump traces of the transaction tracer's internal operation. You're welcome to enable it, but it's unlikely to be edifying unless you're a New Relic Node.js engineer.

Recent changes

Information about changes to the agent are in NEWS.md.

Known issues:

The agent works only with Node.js 0.6 and newer.
The metric names displayed in New Relic are a work in progress. The flexibility of Node's HTTP handling and routing presents unique challenges to the New Relic data model. We're working on a set of strategies to improve how metrics are named, but be aware that metric names may change over time as these strategies are implemented.
There are irregularities around transaction trace capture and display. If you notice missing or incorrect information from transaction traces, let us know.
External requests (and other calls to modules made as part of a transaction) are not being accurately instrumented in many cases.
There are over 20,000 modules on npm. We can only instrument a tiny number of them. Even for the modules we support, there are a very large number of ways to use them. If you see data you don't expect on New Relic and have the time to produce a reduced version of the code that is producing the strange data, it will gratefully be used to improve the agent.
There is an error tracer in the Node agent, but it's a work in progress. In particular, it still does not intercept errors that may already be handled by frameworks. Also, parts of it depend on the new, experimental domain API added in Node 0.8, and domain-specific functionality will not work in apps running in Node 0.6.x.
The CPU and memory overhead incurred by the Node agent is relatively minor (~1-10%, depending on how much of the instrumentation your apps end up using), but may not be appropriate for production use. In particular, GC activity is significantly increased due to the large number of ephemeral objects created by metrics gathering. For now, be judicious about which production apps you install the agent in. It may not be appropriate for latency-sensitive or high-throughput applications.
When using Node's included clustering support, each worker process will open its own connection to New Relic's servers, and will incur its own overhead costs.

To do:

Additional third-party instrumentation:
1. PostgreSQL (probably not pre-GA)
2. CouchDB (not pre-GA)
Log rotation for the agent log.
Better tests for existing instrumentation.
Differentiate between HTTP and HTTPS connections.
Proxy support.
Lots more testing of what the data looks like in RPM.

New Relic features available for other platforms not yet in Node.js

Real User Monitoring (RUM)
custom instrumentation APIs
slow SQL traces and explain plans
custom parameters
supportability metrics
garbage collector instrumentation
full server-side configuration
capacity planning
thread profiling

Support

During the beta, our support bandwidth is limited. We cannot guarantee a specific turn-around on questions and issues. However, we try to reply and resolve issues promptly and we greatly appreciate feedback about how to make the product better.

Please submit a ticket if you don't see the data you expect, if the agent generates an error, if you have a feature that you would like to see, or if you have a library that you would like instrumented. In the ticket, please provide as much information as you can about your application and the issue, including your newrelic_agent.log, package.json and app code snippets.

LICENSE

The New Relic Node.js agent uses code from the following open source projects under the following licenses:

bunyan http://opensource.org/licenses/MIT

The New Relic Node.js agent itself is free-to-use, proprietary software. Please see the full license (found in LICENSE in this distribution) for details.

jandersen / node-newrelic