Exploratory testing - Docker Swarm

It’s Friday night, time to relax after a hard week at work… But what’s this? @alexellisuk posting about a cool plan to create the world’s biggest Docker Swarm cluster… And it’s happening right now!

#swarm3k is a community focused exploratory test, essentially to see just how many nodes could be meshed together using the freshly released Docker 1.12.3 and it’s built-in swarm mode. For more information on Docker Swarm Mode, check out this useful overview blog.

Not one to be left out, I scrambled to help out where I could. At this stage 2,300 nodes were already online. Nine minutes later and our contribution, 10 Digital Ocean droplets were online, with Docker installed and joined to the cluster!


Within an hour, the cluster hit its goal of 3,000 nodes, well within the timeframe allowed. Here’s what that looked like on the sematext dashboard setup to monitor the event:

Swarm Dashboard

Naturally, the team behind this pushed the limits further. That limit this time came at around 4,700 nodes.

Swarm Final

Aside from being a cool experiment, how does this benefit us?

Testing non-functional requirements of open source products can, and should be, something visible and tangible. For a small investment of my time, I got to participate in a really cool experiment. I helped the team push the technology to the next level and I learnt a few things about how Swarm works at scale.

More please!

Written on October 28, 2016 by:
Ed Marshall