Versions | v1.0 (td-agent3)

Aggregate and Analyze Syslog with InfluxDB

This article shows how to collect syslog data into InfluxDB using Fluentd.

Table of Contents

Prerequisites

  • A basic understanding of Fluentd
  • A running instance of rsyslogd

In this guide, we assume we are running td-agent (Fluentd package for Linux and OSX) on Ubuntu Xenial.

Step 1: Install InfluxDB

InfluxDB supports Ubuntu, RedHat and OSX (via brew). See here for the details.

Since we are assumed to be on Ubuntu, the following two lines install InfluxDB:

$ wget https://dl.influxdata.com/influxdb/releases/influxdb_1.7.3_amd64.deb
$ sudo dpkg -i influxdb_1.7.3_amd64.deb

Once it is installed, you can run it with

$ sudo systemctl start influxdb

Then, you can verify that influxDB is running:

$ curl "http://localhost:8086/query?q=show+databases"

If InfluxDB is running normally, you will see an object that contains the _internal database:

{"results":[{"statement_id":0,"series":[{"name":"databases","columns":["name"],"values":[["_internal"]]}]}]}

Also, the following two lines install Chronograf:

$ wget https://dl.influxdata.com/chronograf/releases/chronograf_1.7.7_amd64.deb
$ sudo dpkg -i chronograf_1.7.7_amd64.deb

Once it is installed, you can run it with

$ sudo systemctl start chronograf

Then, go to localhost:8888 (or wherever you are hosting Chronograf) to access Chronograf’s web console which is the successor of InfluxDB’s web console.

Create a database called “test”. This is where we will be storing syslog data.

$ curl -i -XPOST http://localhost:8086/query --data-urlencode "q=CREATE DATABASE test"

If you prefer command line or cannot access port 8083 from your local machine, running the following command creates a database called “test”.

$ curl -i -X POST 'http://localhost:8086/write?db=test' --data-binary 'task,host=server01,region=us-west value=1 1434055562000000000'

We are done for now.

Step 2: Install Fluentd and the InfluxDB plugin

On your aggregator server, set up Fluentd. See here for the details.

$ curl -L https://toolbelt.treasuredata.com/sh/install-ubuntu-xenial-td-agent3.sh | sh

Next, the InfluxDB output plugin needs to be installed. Run

/usr/sbin/td-agent-gem install fluent-plugin-influxdb

If you are using vanilla Fluentd, run

fluent-gem install fluent-plugin-influxdb

You might need to sudo to install the plugin.

Finally, configure /etc/td-agent/td-agent.conf as follows.

<source>
  @type syslog
  port 42185
  tag  system
</source>

<match system.*.*>
  @type influxdb
  dbname test
  flush_interval 10s # for testing.
  host YOUR_INFLUXDB_HOST (localhost by default)
  port YOUR_INFLUXDB_PORT (8086 by default)
</match>

Restart td-agent with sudo service td-agent restart.

Step 3: Configure rsyslogd

If remote rsyslogd instances are already collecting data into the aggregator rsyslogd, the settings for rsyslog should remain unchanged. However, if this is a brandnew setup, start forward syslog output by adding the following line to /etc/rsyslogd.conf

*.* @182.39.20.2:42185

You should replace “182.39.20.2” with the IP address of your aggregator server. Also, there is nothing special about port 42185 (do make sure this port is open though).

Now, restart rsyslogd.

$ sudo systemctl restart rsyslog

Step 4: Confirm Data Flow

Your syslog data should be flowing into InfluxDB every 10 seconds (this is configured by flush_interval).

Clicking on “Explore” brings up the query interface that lets you write SQL queries against your log data.

And then click “Visualization” and select line chart.

Here, I am counting the number of lines of syslog messages per facility/priority:

SELECT COUNT(ident) FROM test.autogen./^system\./ GROUP BY time(1s)

Click on “Submit Query” and you get a graph like this.

Here is another screenshot just for the system.daemon.info series.

Last updated: 2019-02-19 16:32:56 +0000

Versions | v1.0 (td-agent3)

If this article is incorrect or outdated, or omits critical information, please let us know. Fluentd is a open source project under Cloud Native Computing Foundation (CNCF). All components are available under the Apache 2 License.