Managing Microservices Effectively

Daniel Hall (@smarthall)

About Me

• Systems Engineer at LIFX
• Making the 'Internet' in the Internet of Things

About This Talk

• This is how we do things at LIFX
• Feel free to ask questions as we go
• It works for us, it might not work for you
• Think about how each bit fits into your situation

Step One: Write your apps

• You may not get input into this part
• Micro services are popular at the moment
• Design pattern that works with continuous delivery

Microservices

• Try to keep as much state outside your apps
• Don't make them too small, they're not nanoservices
• Don't make them too big, they're not milliservices
• Each service should be
  • Replacable
  • Independently Deployable
  • Have a single capability (billing, authentication)
• Think about information flow and circular dependencies

The Hype Curve

Jeremy Kemp CC-BY-SA

(http://commons.wikimedia.org/wiki/File:Gartner_Hype_Cycle.svg)

Microservices

Step Two: Packaging

• All dependencies need to be available
• Needs to be small or cachable
  • Faster install means faster deployments
• You might want multiple versions on the same machine
• Preferably it works in several environments

Docker

• Filesystem layers stacked on top of each other
• Uses Linux containers to isolate applications
• You can run a local Docker registry
  • Security
  • Speed
• You can run it locally in dev and on your servers
• Less of 'it works on my laptop'
• Minuscule performance hit compared to VMs

The Hype Curve

Jeremy Kemp CC-BY-SA

(http://commons.wikimedia.org/wiki/File:Gartner_Hype_Cycle.svg)

Docker

Step Three: Deployment

• As fast as possible
• Preferably minimal interaction
• Recovery from failures

Mesos/Marathon

• Mesos manages tasks running on a cluster
• Marathon coordinates long running jobs
• You submit a JSON job description to Marathon
• Marathon handles switching from the old app to new
• Marathon will also handle task failure and recover
• Health checks ensure broken tasks get replaced

The Hype Curve

Jeremy Kemp CC-BY-SA

(http://commons.wikimedia.org/wiki/File:Gartner_Hype_Cycle.svg)

Mesos/Marathon

Extra Credit: Sheduling

• Some things need to run repeatedly
• Cron works, but its not really HA
• HA Crons exist but can be complex
• Your cluster probably has spare capacity

Chronos

• Chronos runs your scheduled tasks in Mesos
• Uses ISO8601 intervals to specify schedules
• Use your spare capacity for repeating tasks
• Can rerun failing jobs
• Can handle job dependencies
• Records stats on run times for jobs

The Hype Curve

Jeremy Kemp CC-BY-SA

(http://commons.wikimedia.org/wiki/File:Gartner_Hype_Cycle.svg)

Chronos

Summary

Demo

https://github.com/smarthall/ansible-mesos

Demo Time!

• All the code is on Github
  
  • https://github.com/smarthall/ansible-mesos
    
• 'vagrant up' will give you a development cluster
  
• './init-cluster.sh' will add some sample apps