"Examples" Posts


Quick & dirty log monitoring

By Derek Bullet_white Posted in Examples Bullet_white Comments Comments

Sometimes we have an immediate need to watch for a term in a log file. For example, if we’re doing a major deploy, we might watch for the term error in a log file. We want to make sure the rate of errors doesn’t increase.

To do this, we’ll use Yaroslav Lazor’s Log Watcher Scout Plugin. We just had a great use case for this.

Yesterday we released a preview of Redwood, a MacRuby app we’re building. Redwood works just like Spotlight on your OSX desktop but searches the web apps we commonly use at Scout (Gmail, Google Docs, and Basecamp).

To track the number of downloads, we configured the plugin to watch for the term Redwood.zip in the Apache access log and pow we’re tracking Redwood downloads:

redwood_downloads

This continues to be one of my favorite Scout plugins: the biggest reason we don’t monitor important metrics is that setting up monitoring is a pain. This plugin eliminates that excuse.

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Scaling Illustrated

By Derek Bullet_white Posted in Examples Bullet_white Comments Comments

Last week we added a third web server to one of our reporting applications. We’ve been growing at a steady rate and we wanted to reduce the load across our web tier (losing one of the web servers could put too much traffic on the remaining server).

Before Will Farrington (one of the fine folks at Rails Machine) added the third web server to the load balancer rotation, we setup a couple of charts to watch the magic.

Scout’s charts now refresh as metrics are reported so we could quickly see the impact.

Did the third web server help? Here’s what we saw:

Server Load

Our third web server helped decrease the load across our web tier:

Scout’s Server Load plugin is installed by default on your server.

Request Distribution

We confirmed the change in request distribution across the 3 web servers:

Install either the Apache or Ruby on Rails Monitoring plugin to view request metrics.

We love seeing visual confirmation of a job well done!

 

Understanding Linux CPU Load - when should you be worried?

By Andre Bullet_white Posted in Examples Bullet_white Comments 16 comments

You might be familiar with Linux load averages already. Load averages are the three numbers shown with the uptime and top commands - they look like this:

load average: 0.09, 0.05, 0.01

Most people have an inkling of what the load averages mean: the three numbers represent averages over progressively longer periods of time (one, five, and fifteen minute averages), and that lower numbers are better. Higher numbers represent a problem or an overloaded machine. But, what's the the threshold? What constitutes "good" and "bad" load average values? When should you be concerned over a load average value, and when should you scramble to fix it ASAP?

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Monitoring Amazon EC2 Instances

By Derek Bullet_white Posted in Examples, HowTo Bullet_white Comments Comments

UPDATED – We’ve made it even easier to monitor ec2 instances. Check out our post on cloud monitoring.

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Taking the guesswork out of scaling

By Derek Bullet_white Posted in Examples Bullet_white Comments Comments

Determining a web application’s hardware resources isn’t easy (or cheap). Frankly, it’s often just guesswork. Even when you build benchmarking scripts, they can miss key behaviors and ignore important metrics.

Scaling becomes a lot less stressful when you can quickly compare a history of your application data with server performance.

For example, we did this to get a better understanding of how our Scout server performed during our invitation process. The graph below was generated through Scout and shows the relationship between user accounts and the server load. As we expected, the overall load on the server increased as the number of accounts increased. Scout shows us how this data is correlated – it gives us an idea of how many accounts our current hardware can support.

Scout Accounts vs. Server Load
accounts vs load

It’s trivial process to regularly feed Scout your application data (user signups, orders, revenue, etc):

  1. Start with this Rails App Plugin Sample (this assumes a Ruby on Rails application, but you can do this with any framework/language)
  2. Grab your application data – just use ActiveRecord!
  3. Put the plugin on your server (can protect behind basic auth)
  4. Add the plugin
 

Graphing Rails Performance With Scout

By Derek Bullet_white Posted in Examples Bullet_white Comments Comments

We’re using Scout, our monitoring and reporting application, to graph the performance of our Rails applications and servers.

I’ve uploaded a video that looks at how one of our applications, PlaceShout, impacts the server load and Mongrel memory usage. I also compare PlaceShout’s footprint to another server.

Watch the video: Graphing in Scout (1 min 47 sec)

Past Videos on Scout:

Installing the Scout Client (1 min 39 sec)

Installing the Rails Requests Plugin (1 min 55 sec)

Signup for our launch email list

We’ve started emailing invites to Scout. Signup on our homepage, and we’ll give you access to Scout before the public launch.

 

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