ScrollKeeper Is a Collaboration Tool for Researchers

Copied URL with current time.
0:00 / 0:00

In this episode of Running in Production, Ian Butler goes over building a collaboration tool for researchers called Scrollkeeper. Ian is all-in with AWS and hosting costs about $400 / month for a multi-node AWS ECS cluster. It’s been up and running since mid 2019.

His app is ~8,000 lines of Elixir code and there are a few things being done through AWS Lambda. We talked about ways to run various AWS services locally, auto-scaling, background workers, developing a custom caching solution and a whole lot more.

Topics Include

  • 1:19 – Working on it during nights and weekends as a part time project
  • 2:03 – Motivation for using Phoenix and Elixir
  • 3:09 – Ian is confident that if it came down to it, he could hire Elixir developers later
  • 3:43 – Generally speaking it’s a monolithic app but it has a few tiny services broken out
  • 4:15 – At the moment there’s not much benefit in breaking it out into umbrella apps
  • 4:50 – The main app is about 8,000 lines of Elixir and it’s using Phoenix contexts
  • 5:21 – Phoenix has some opinions but you still need to make a lot of decisions
  • 5:48 – A couple of context names that are used in the main app
  • 6:34 – Parsing PDF files and doing some work in the background
  • 7:40 – Phoenix channels are used to ferry back the parser’s status to the user
  • 7:54 – Live View isn’t currently being used
  • 8:08 – It’s a split app style with a Phoenix API and a React front-end
  • 8:24 – Live View currently doesn’t have enough features to replace a React app
  • 10:20 – The PDF parsing rabbit hole goes quite deep
  • 10:51 – AWS ECS, AWS Lambda and a service called Spotinst helps run and scale the app
  • 12:16 – Docker isn’t being used in development but tests are run in Docker
  • 12:52 – Gitlab CI handles testing, building images and pushing them to ECR
  • 13:54 – Why exactly isn’t Docker being used in development?
  • 14:41 – Testing various AWS services locally using Local Stack
  • 16:21 – Local Stack is open source and free but they also have a paid tier if you want it
  • 17:32 – PostgreSQL is the primary database and S3 is used for storing flat files
  • 17:54 – The ex_aws library is used to connect to AWS using Elixir
  • 18:43 – Caching is being done directly in Elixir with a custom GenServer approach
  • 20:27 – What exactly is being cached? Mainly the PDF documents
  • 21:11 – nginx isn’t being used because AWS’ API Gateway and load balancers fill that role
  • 21:26 – Static files are being hosted with AWS CloudFront (CDN)
  • 21:53 – Going all-in with AWS and being very happy with it for productivity
  • 22:57 – 3 to 6 EC2 instances are used in the ECS cluster depending on the load
  • 23:14 – Scaling up is automated and takes about 30 seconds
  • 23:37 – Spotinst helps with that by having idle machines that are ready to go
  • 23:57 – The highest load comes from uploading many fairly large PDF files in parallel
  • 24:44 – Between AWS’ and Spotinst’ logs and alarms, it’s easy to keep an eye on the load
  • 25:53 – Stripe is being used to handle payments and the payment strategy is interesting
  • 26:58 – Moving to Stripe’s hosted checkout eventually would remove a lot of stress
  • 27:46 – Currently PaymentIntents and SCA isn’t supported by choice
  • 29:10 – Handling payments was the last feature that was added to the app before shipping
  • 30:16 – PayPal isn’t supported yet because there’s only so many hours in the day
  • 31:09 – The only emails being sent out are for user actions which is handled by Cognito
  • 32:01 – Walking us through a deployment from development to production
  • 33:13 – ECS has gotten a little nicer to work with in regards to updating services
  • 34:17 – Having issues with AWS App Mesh and Envoy due to issues with websockets
  • 36:27 – Secrets are managed with env variables hard coded into the task definition files
  • 37:56 – The AWS web console is starting to become quite good
  • 39:14 – Rolling restarts are done over ECS to deploy without downtime
  • 39:52 – How do you deal with draining worker connections to avoid losing partial uploads?
  • 41:11 – Rihanna is an Elixir job processing library backed by PostgreSQL
  • 42:00 – You usually end up needing a job processing library even with Elixir
  • 44:03 – As for backups, all of the data and flat files are backed up and could be recovered
  • 44:45 – IP bans at the firewall level helps with denial of service attacks
  • 45:48 – Everything together on AWS costs about $400 / a month
  • 47:13 – Gust Launch gave him $15,000 in AWS credits for starting a business with them
  • 48:38 – Trying to crash things on purpose by throwing massive traffic at it
  • 49:25 – Thinking that all users are out to get you and designing your app to be robust
  • 50:18Plug.Upload goes straight to S3 to handle file uploads
  • 51:31 – Best tips? Profile and load test your app before you launch your app publicly
  • 52:35 – If you have a lot of task based jobs, look into using Lambda early on
  • 54:06 – Check out Scrollkeeper, also Ian is on Twitter and GitHub
  • 54:41 – Ian also wrote a blog post series on writing your own web crawler in Elixir
📄 References
⚙️ Tech Stack
🛠 Libraries Used

Support the Show

This episode does not have a sponsor and this podcast is a labor of love. If you want to support the show, the best way to do it is to purchase one of my courses or suggest one to a friend.

  • Dive into Docker is a video course that takes you from not knowing what Docker is to being able to confidently use Docker and Docker Compose for your own apps. Long gone are the days of "but it works on my machine!". A bunch of follow along labs are included.
  • Build a SAAS App with Flask is a video course where we build a real world SAAS app that accepts payments, has a custom admin, includes high test coverage and goes over how to implement and apply 50+ common web app features. There's over 20+ hours of video.

Questions

Jan 20, 2020

✏️ Edit on GitHub