NGINX InfluxDB Module 🦄

A module to monitor request passing trough an NGINX server by sending every request to an InfluxDB backend exposing UDP.

Exported Fields (per request)

Metric	Type	Description
method	string	The HTTP request method that has been given as a reply to the caller
status	integer	The HTTP status code of the reply from the server (refer to RFC 7231 for more details)
bytes_sent	integer	The number of bytes sent to a client body + header
body_bytes_sent	integer	The number of bytes sent to a client only for body
header_bytes_sent	integer	The number of bytes sent to a client for header and body
request_length	integer	Request length (including request line, header, and request body)
uri	string	The called uri (e.g: /index.html)
extension	string	The extension of the served file (e.g: js, html, php, png)
content_type	string	The content type of the response (e.g: text/html)
request_time	string	Request processing time in seconds with a milliseconds resolution

Dynamic fields (per request)

You can enrich the exported field set with some custom fields using the influxdb_dynamic_fields directive. Your fields need to be compliant with the line protocol in terms of type and quoting, see here for more details.

This means that if you use a string in the directive it must be double quoted, like:

influxdb_dynamic_fields myfield="mystring";

If you are using a variable to populate that field it must meet the same criteria as a normal string:

set namespace myapp
influxdb_dynamic_fields namespace="$namespace";

On the other end, an integer doesn't want to be escaped:

influxdb_dynamic_fields namespace=100;

But since InfluxDB assumes that all numerical field values are float you might want to specify that it is an integer instead if your numeric value is:

influxdb_dynamic_fields namespace=100i;

If you want to know more about Data types supported in line protocol read the Data Types section in the line protocol documentation.

Please remember that the metrics are sent after the request is processed so if a metric fails to be ingested by InfluxDB because of line protocol formatting you will not have it in the database, refer to the logs in that case.

The module doesn't do any quotes escaping or check on dynamic fields for performances reasons.

Installation

From pre-built dynamic modules

Pre-built dynamic modules are not available (yet)

Build the module statically with NGINX

mkdir build
pushd build
git clone [email protected]:fntlnz/nginx-influxdb-module.git
wget -nv -O - https://nginx.org/download/nginx-1.15.3.tar.gz | tar zx
pushd nginx-1.15.0
./configure --add-module=../nginx-influxdb-module
make -j
popd
popd

Build the module dinamically to be loaded within NGINX

Writing this in a snap!

Configuration

To configure it you just need the influxdb directive.

Please be aware that you are configuring the module to write to InfluxDB via UDP, this means that host can only be an IP address and not an hostname and that the port is configured to serve a database via UDP.

Pre-defined fields example

influxdb server_name=myserver host=127.0.0.1 port=8089 measurement=mymeasures enabled=true;

If you don't want to expose InfluxDB via UDP you can start a Telegraf bound to 127.0.0.1 that is exposing UDP using the socket listener service plugin, then you can send the data via HTTP to your InfluxDB using the InfluxDB Output Plugin. The approach using telegraf on localhost has the advantage that you can "offload" requests to Influx, you can send requests in batch using a time window and that since 127.0.0.1 is on the loopback interface you have an MTU of 65536 that is extremely higher than the usual 1500.

You can find a sample configuration for InfluxDB to expose UDP in hack/influxdb.conf.

Dynamic fields example

# Normally you have only this
influxdb server_name=myserver host=127.0.0.1 port=8089 measurement=mymeasures enabled=true

# If you want to use dynamic fields too
set namespace myapp
influxdb_dynamic_fields namespace="$server_name" user_agent="$http_user_agent" myinteger=10000;

Full Example

A full example config looks like this

user  nginx;
worker_processes  auto;
daemon off;

#load_module path/to/the/module/ngx_http_influxdb_module.so; needed if a dynamic module
pid        /var/run/nginx/nginx.pid;


events {
    worker_connections  1024;
}

http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    sendfile        on;

    keepalive_timeout  65;

    server {
        listen       8080;
        server_name  localhost;
        location / {
            root   /usr/share/nginx/html;
            influxdb server_name=myserver host=127.0.0.1 port=8089 measurement=mymeasures enabled=true;
            influxdb_dynamic_fields namespace="mynamespace" server_name="$server_name" user_agent="$http_user_agent" myinteger=10000;
            index  index.html index.htm;
        }

        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   /usr/share/nginx/html;
        }
    }

}

Local Testing

To test changes locally, there's a script in hack/ called build-start.sh that can build the local changes against the current nginx source code taken from github.

To run, the script also requires docker in order to start influxdb, chronograf and other testing proxy backends

./hack/build-start.sh

• You can reach chronograf (through nginx) at http://127.0.0.1:8082/
• You can reach chronograf (directly) at http://127.0.0.1:8888/
• A static hello world page can be reached at http://127.0.0.1:8080

You can access the influxdb instance CLI via:

 docker exec -it test-nginx-influxdb influx