"Development" Posts

Why we don't schedule deployments during off-hours

By Derek Bullet_white Posted in Development Bullet_white Comments Comments

Years back, before Scout, I used to schedule deployments outside the regular workday. I didn’t give it much thought – it was what my consulting clients were used to. However, we changed that practice with Scout.

Many web applications, including Scout, have customers around the world. There isn’t a perfect time for a deployment. With that in mind, we started scheduling deployments when it’s best for us.

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5 Pillars of Rails Cluster Monitoring

By Derek Bullet_white Posted in Development Bullet_white Comments Comments

Photo by mollypop

My how you’ve grown! A couple of years ago your little Rails app was on a single server. Now you’re on a whole cluster – you’ve got web servers, database servers, HAProxy servers, and more. I’m so proud of you!

Monitoring your Rails cluster has gotten more difficult though, huh? When it comes to monitoring a cluster of servers, there are lots of options with overlapping features. Some products are open source, some aren’t. Some are hosted, some aren’t. At Scout, we’re very happy with our monitoring stack. We know a bit about monitoring, so what are we using under the hood to monitor our Rails/Sinatra cluster?

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Determining free memory on Linux

By Derek Bullet_white Posted in Development Bullet_white Comments Comments

When checking the amount of free memory on a Linux server, it’s easy to think you’re running out of memory when you’re not.

For example, here’s the output of free -m on a server with 4GB of RAM:

With a quick glance, you might start sweating. Only 39 MB of free memory? Put down the antacid – you’ve got a lot more free memory than you think.

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RVM and cron in production

By Andre Bullet_white Posted in Development Bullet_white Comments Comments

UPDATED 6/7/2013We no longer recommend using bash -l -c to run Cron jobs with RVM. See our updated approach .

This info is for Scout users, but it’s also applicable to anyone who’s wondered how to use cron together with RVM. This assumes 1) you are using bash; 2) you running you cron tasks as a non-root user (say, “deploy”).

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A Holodeck for deployments?

By Derek Bullet_white Posted in Development Bullet_white Comments Comments

Recently I watched the documentary miniseries When We Left Earth. A constant theme from early space flight was the huge number of unknowns. For example, before the first astronaut went into orbit, NASA had concerns humans would lose their vision and wouldn’t be able to swallow in zero gravity. Thankfully, space worked out.

In devops lingo, it was impossible to build an accurate staging environment.

At Scout, we’ve grown almost 600% since last August. With that growth, our deployments are more carefully executed. This is monitoring, so Scout needs to be reliable when we deploy changes.

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