Nginx requests, memory usage and connections statistics with Munin

Introduction

These three perl scripts are Munin plugins for monitoring the nginx HTTP server.

nginx_status

Based on the one provided in the Debian munin-node package. Which is itself a modified version of the one available at the Munin Plugin Exchange. It shows the connection status for nginx.

Presents the values returned by nginx, using the http_stub_status module, are respectively, the number of:

connections initiated, connections handled, requests served

nginx_connection_request

Presents the number of requests served by connection handled by nginx. The requests-connection ratio handled by the server is the ratio:

requests served / connections handled

This is implemented as a RRDtool datasource of type GAUGE, the default type for Munin.

nginx_request

Based on the one provided in the Debian munin-node package. Which is itself a modified version of the one available at the Munin Plugin Exchange.

It uses a derivative (technically a finite difference) to compute the connection rate value.

nginx_memory

Based on a previous plugin by AkyRhO. It uses ps and awk to get the memory used by the master and worker processes of nginx.

Installation & Configuration

1. Copy all the scripts to /etc/munin/plugins.
2. Restart the munin-node daemon: /etc/init.d/munin-node restart.
3. Done. You should now start to see a new section nginx in your Munin pages with the corresponding graphs.
4. All scripts have POD documentation. Issue perldoc <script name> to read them.

Environment Settings

Both nginx_request and nginx_status accept two environment variables:

• URL: the URL of the nginx status data. The default value is:

  http://hostname/nginx_status

• UA: the User Agent that the plugin sends in the HTTP header. Since most sites block the libwww-* user agent to get rid of bad bots and mostly up to no good scanners, the scripts send a different User Agent to get around that.

Both variables can be specified in the /etc/munin/plugin-conf.d/munin-node file.

Something like this for altering the URL:

[nginx_status] env.url=http://hostname:8888/nginx-status nginx_status

[nginx_connection_request] env.url=http://hostname:8888/nginx-status nginx_status

[nginx_request] env.url=http://hostname:8888/nginx-status nginx_status

Add env.ua for altering the User Agent.

Don’t forget to restart the munin-node daemon as described in step 2 of the installation instructions above.

Note: the github handling of Org mode markup is broken. Therefore the [nginx_status] [nginx_connection_request] and [nginx_request] lines are separate from the lines specifying the environment variables.

It’s not github’s responsibility but rather a bug in Org-Ruby.