Nginx

Agent Check

Overview

The Datadog Agent can collect many metrics from NGINX instances, including:

• Total requests
• Connections (accepted, handled, active)

For users of NGINX Plus, the commercial version of NGINX, the Agent can collect the significantly more metrics that NGINX Plus provides, like:

• Errors (4xx codes, 5xx codes)
• Upstream servers (active connections, 5xx codes, health checks, etc)
• Caches (size, hits, misses, etc)
• SSL (handshakes, failed handshakes, etc)

And many more.

Setup

Installation

The NGINX check is packaged with the Agent, so simply install the Agent on your NGINX servers.

NGINX status module

The NGINX check pulls metrics from a local NGINX status endpoint, so your nginx binaries need to have been compiled with one of two NGINX status modules:

• stub status module – for open source NGINX
• http status module – only for NGINX Plus

NGINX Plus packages always include the http status module, so if you’re a Plus user, skip to Configuration now. For NGINX Plus release 13 and above, the status module is deprecated and you should use the new Plus API instead. See the announcement for more information.

If you use open source NGINX, however, your instances may lack the stub status module. Verify that your nginx binary includes the module before proceeding to Configuration:

$ nginx -V 2>&1| grep -o http_stub_status_module
http_stub_status_module

If the command output does not include http_stub_status_module, you must install an NGINX package that includes the module. You can compile your own NGINX—enabling the module as you compile it—but most modern Linux distributions provide alternative NGINX packages with various combinations of extra modules built in. Check your operating system’s NGINX packages to find one that includes the stub status module.

Configuration

Create a nginx.yaml file in the Agent’s conf.d directory.

Prepare NGINX

On each NGINX server, create a status.conf file in the directory that contains your other NGINX configuration files (e.g. /etc/nginx/conf.d/).

server {
  listen 81;
  server_name localhost;

  access_log off;
  allow 127.0.0.1;
  deny all;

  location /nginx_status {
    # Choose your status module

    # freely available with open source NGINX
    stub_status;

    # for open source NGINX < version 1.7.5
    # stub_status on;

    # available only with NGINX Plus
    # status;
  }
}

NGINX Plus can also use stub_status, but since that module provides fewer metrics, you should use status if you’re a Plus user.

You may optionally configure HTTP basic authentication in the server block, but since the service is only listening locally, it’s not necessary.

Reload NGINX to enable the status endpoint. (There’s no need for a full restart)

Metric Collection

• Add this configuration setup to your nginx.yaml file to start gathering your NGINX metrics:

  init_config:

  instances:
    - nginx_status_url: http://localhost:81/nginx_status/
    # If you configured the endpoint with HTTP basic authentication
    # user: <USER>
    # password: <PASSWORD>

See the sample nginx.yaml for all available configuration options.

• Restart the Agent to start sending NGINX metrics to Datadog.

Log Collection

Available for Agent >6.0

• Collecting logs is disabled by default in the Datadog Agent, you need to enable it in datadog.yaml:

  logs_enabled: true

• Add this configuration setup to your nginx.yaml file to start collecting your NGINX Logs:

  logs:
    - type: file
      path: /var/log/nginx/access.log
      service: nginx
      source: nginx
      sourcecategory: http_web_access

    - type: file
      path: /var/log/nginx/error.log
      service: nginx
      source: nginx
      sourcecategory: http_web_access

Change the service and path parameter values and configure them for your environment. See the sample nginx.yaml for all available configuration options.

• Restart the Agent

Learn more about log collection on the log documentation

Validation

Run the Agent’s status subcommand and look for nginx under the Checks section:

  Checks
  ======
    [...]

    nginx
    -----
      - instance #0 [OK]
      - Collected 7 metrics, 0 events & 1 service check

    [...]

Compatibility

The NGINX check is compatible with all major platforms.

Data Collected

Metrics

Not all metrics shown are available to users of open source NGINX. Compare the module reference for stub status (open source NGINX) and http status (NGINX Plus) to understand which metrics are provided by each module.

A few open-source NGINX metrics are named differently in NGINX Plus; they refer to the exact same metric, though:

These metrics don’t refer exactly to the same metric, but they are somewhat related:

Finally, these metrics have no good equivalent:

Events

The NGINX check does not include any event at this time.

Service Checks

nginx.can_connect:

Returns CRITICAL if the Agent cannot connect to NGINX to collect metrics, otherwise OK.

Troubleshooting

You may observe one of these common problems in the output of the Datadog Agent’s info subcommand.

Agent cannot connect

  Checks
  ======

    nginx
    -----
      - instance #0 [ERROR]: "('Connection aborted.', error(111, 'Connection refused'))"
      - Collected 0 metrics, 0 events & 1 service check

Either NGINX’s local status endpoint is not running, or the Agent is not configured with correct connection information for it.

Check that the main nginx.conf includes a line like the following:

http{

  ...

  include <directory_that_contains_status.conf>/*.conf;
  # e.g.: include /etc/nginx/conf.d/*.conf;
}

Otherwise, review the Configuration section.

Further Reading

Knowledge Base

The data pulled from the NGINX Plus status page are described in the NGINX docs.

Datadog Blog

Learn more about how to monitor NGINX performance metrics thanks to our series of posts. We detail the key performance metrics, how to collect them, and how to use Datadog to monitor NGINX.