Couchmate Is a Social Chat Platform for Viewers of Live TV

In this episode of Running in Production, Matt Oliver goes over building a chat platform with Akka, Scala and React Native. It’s hosted on DigitalOcean with Kubernetes and has been running in production since 2013.

Matt talks about rewriting his app a few times, handling tens of thousands of nightly TV shows, going all-in with Kubernetes, using Terraform, understanding it’ll take a while to learn things along the way and more.

Topics Include

• 4:55 – Going from PHP to Scala to Node and back to Scala for the back-end
• 15:09 – Tens of thousands of channels are created every night
• 16:39 – What exactly is Akka and the actor model
• 19:55 – Websockets are being used quite heavily
• 23:04 – A few Scala libraries that were useful for building this platform
• 27:31 – There’s a mobile front-end using React Native for Android and iOS
• 31:30 – Storing and caching TV listings with Gracenote
• 34:53 – Roughly ~25k lines of Scala and ~11k on the front-end in 2 repos
• 39:41 – Motivation for using React Native instead of using native languages
• 45:55 – How to deal with large show TVs with a massive audience
• 50:28 – The app is basically 3 screens
• 54:34 – Handling user uploaded gifs and link submissions
• 1:00:09 – What it was like building out the React Native front-end
• 1:05:54 – Reasons for picking DigitalOcean and using Kubernetes
• 1:14:44 – Most of the infrastructure is managed by Terraform
• 1:16:57 – What it was like to go from not using Kubernetes to going all-in with it
• 1:24:21 – (3) 2 GB of memory / 2 CPU core servers are running the cluster
• 1:26:12 – What it’s like developing a new feature and deploying it to production
• 1:34:28 – The database is backed up on a schedule and before schema changes
• 1:39:21 – Prometheus, Grafana, Kamon and Sentry are used for metrics and monitoring
• 1:43:41 – Pingdom is used for an external site monitor
• 1:44:31 – It took about a month to get confident in using Kubernetes
• 1:49:29 – Best tips? It’s going to take a while, hang in there
• 1:53:06 – Writing comments for your future self while learning
• 1:54:34 – Matt is on Twitter and most socials as @halfmatthalfcat and @couchmatehq

Links 📄 References

• https://en.wikipedia.org/wiki/Electronic_program_guide
• https://www.gracenote.com/on-entertainment-tv-listings/
• https://en.wikipedia.org/wiki/Language_Integrated_Query
• https://tenor.com/

⚙️ Tech Stack

• akka →
• scala →
• react-native →
• cloudflare →
• digitalocean →
• github-actions →
• grafana →
• kamon →
• kubernetes →
• lets-encrypt →
• mailgun →
• pingdom →