Using Sensors with your VM Images

Introduction

tcollector is a simple program that provides sensor monitoring information about your deployed virtual machines. It works with the OpenTSDB Monitoring System to keep track of the metrics of your Virtual Machines, which Phantom can use to scale the VMs for your application. This guide explains how to install tcollector on your VM image.

If you don’t want to install tcollector on an image, and are only looking to test Phantom’s sensor capabilities, please try the Phantomize contextualization which will install and run tcollector automatically when your instances boot, or use an already configured VM image such as the hello-phantom.gz image available on FutureGrid clouds. You may also base your application image on it.

Installation and Prerequisites

tcollector requires that you have (at least) Python 2.6 installed on your VM image. This can generally be installed with your distribution’s package manager, or built from source from python.org.

Once you have Python installed, you can install it like so:

# wget https://build.nimbusproject.org:8001/tcollector/master/tcollector-HEAD.tar.gz
# tar xzvf tcollector-HEAD.tar.gz
# mv tcollector /usr/local/tcollector

That’s it! You can start tcollector like so to test it:

# /usr/local/tcollector/tcollector.py --host nimbus-opentsdb.no-ip.info --port 4242

Now to make tcollector start on system start, you can use the provided startstop script. Install it like so:

# cp /usr/local/tcollector/startstop /etc/init.d/tcollector

Note

If you are running your VM on OpenStack clouds running OpenStack (except for Hotel), the public hostname sent by the cloud metadata server does not match what is sent by the EC2 interface which uses the public IP. For these clouds, we have an alternative script available, which works around the problem.

Instead of the above command, use:

Open up the script and set the TSD_HOST variable to point to the Phantom OpenTSDB installation:

# vim /etc/init.d/tcollector

Line 5 should look like:

TSD_HOST=nimbus-opentsdb.no-ip.info

You can confirm that you’ve set this right by running the following, and verifying that the output is the same:

# grep 'TSD_HOST=' /etc/init.d/tcollector
TSD_HOST=nimbus-opentsdb.no-ip.info

You will now want to set this init script to start on boot. To do this on Debian or Ubuntu based distros, you will want to use update-rc.d:

# update-rc.d tcollector defaults

On Redhat based distros like CentOS and Scientific Linux, you will want to use chkconfig:

# /sbin/chkconfig --add tcollector

Now save your image, and you’re finished.

Custom Sensors

Creating custom tcollector sensors is easy. To do this, you simply need to create a script that periodically outputs your metric data. As an example:

#!/usr/bin/python
import sys
import time
COLLECTION_INTERVAL = 15  # seconds

while True:
    ts = int(time.time())
    print "test.my.value %s 42" % ts
    sys.stdout.flush()
    time.sleep(COLLECTION_INTERVAL)

When this script is running on your VM, you will have the test.my.value metric available.

If you would like to create your own sensors, check out the tcollector documentation, and for inspiration, check out the phantom sensors that are included with the tcollector tarball.

Domain Sensors

If you would like to set up a sensor that is not associated with a particular hostname, that is simple as well. You may want to do this if you would like to scale based on some external metric, like say you had a system set up with Torque on a static headnode, and you set Phantom up to scale based on your queue length.

Installing tcollector

Installing tcollector to use as a domain sensor is simple, and very similar to installing it on your VM image.

tcollector requires that you have (at least) Python 2.6 installed on your VM image. This can generally be installed with your distribution’s package manager, or built from source from python.org.

Once you have Python installed, you can install it like so:

# wget https://build.nimbusproject.org:8001/tcollector/master/tcollector-HEAD.tar.gz
# tar xzvf tcollector-HEAD.tar.gz
# mv tcollector /usr/local/tcollector

That’s it! You can start tcollector like so to test it:

# /usr/local/tcollector/tcollector.py --host nimbus-opentsdb.no-ip.info --port 4242

Now to make tcollector start on system start, you can use the provided startstop script. Install it like so:

# cp /usr/local/tcollector/startstop /etc/init.d/tcollector

Open up the script and set the TSD_HOST variable to point to the Phantom OpenTSDB installation:

# vim /etc/init.d/tcollector

Line 5 should look like:

TSD_HOST=nimbus-opentsdb.no-ip.info

You can confirm that you’ve set this right by running the following, and verifying that the output is the same:

# grep 'TSD_HOST=' /etc/init.d/tcollector
TSD_HOST=nimbus-opentsdb.no-ip.info

You will now want to set this init script to start on boot. To do this on Debian or Ubuntu based distros, you will want to use update-rc.d:

# update-rc.d tcollector defaults
 Adding system startup for /etc/init.d/tcollector ...
   /etc/rc0.d/K20tcollector -> ../init.d/tcollector
   /etc/rc1.d/K20tcollector -> ../init.d/tcollector
   /etc/rc6.d/K20tcollector -> ../init.d/tcollector
   /etc/rc2.d/S20tcollector -> ../init.d/tcollector
   /etc/rc3.d/S20tcollector -> ../init.d/tcollector
   /etc/rc4.d/S20tcollector -> ../init.d/tcollector
   /etc/rc5.d/S20tcollector -> ../init.d/tcollector

On Redhat based distros like CentOS and Scientific Linux, you will want to use chkconfig:

# /sbin/chkconfig --add tcollector

Now save your image, and you’re finished.

Configuring tcollector for your Domain

Now that you have tcollector installed, you can configure it to push metrics for your domain. To do this, open up the configuration as follows:

# vim /usr/local/tcollector/collectors/etc/config.py

and set the USER and DOMAIN lines to your Phantom username and Domain, by removing the leading ‘#’ and setting the correct values. Check your values with:

# egrep '^USER|^DOMAIN' /usr/local/tcollector/collectors/etc/config.py
USER = "iamauser"
DOMAIN = "iamadomain"

You will probably also want to remove the existing metrics, since they probably won’t be helpful to your domain. You can do this with:

# rm /usr/local/tcollector/collectors/0/*

You can now place your custom domain collector into your tcollector install:

# cp mycollector.py /usr/local/tcollector/collectors/0/

Using Domain Metrics with Phantom

Use these metrics in the same way you use regular host metrics, but prefix the name of the metric with “domain:” for example, with a metric named my.domain.metric, use “domain:my.domain.metric” when adding the sensor, the same way that is explained in the Phantom Quickstart.

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