ZIO workshop

Welcome to gentle introduction to Effect systems using ZIO. Goal of this exercise is to show you how to use ZIO to solve real world problems. Hopefully, it will show you that by using ZIO you will get to functional implementation that is simple to reason about.

The intended way to go through this exercise is to start implementing modules. Each module contains basic description of the task and some hints on how to go about implementing them. It also contains dummy implementation (PipelineStage.delegate) which you are supposed to replace with your own implementation.

Modules are ordered in order from easiest to hardest. This is of course subjective but we tried our best.

You can start by taking a look at _00accesslog for reference implementation of module. It contains code that logs all successful or failed requests.

Reference implementations will be revealed few days after the workshop to allow people to experiment at home.

Requirements

Unfortunately, we are not Windows developers so if you are using Windows machine, you are on your own. If you are using Linux or MacOS, you need following:

curl installed (if you want to use tools provided by us)
sbt installed
Docker and docker-compose installed
IDE / editor that supports SBT / Scala projects

Running the project

First you need to bring up postgres

docker-compose up # brings up the postgres

Starting proxy from terminal:

./run-proxy.sh

Running from SBT shell:

runMain com.avast.zioworkshop.zioworkshop.Main

You can also run the app from IDE, i'm sure you know how to do that ;)

Useful resources:

zio docs - zio docs and getting started
zio api docs - scaladoc for zio api
httpstatus - simple service that always return http status based on path - for example curl http://httpstat.us/500 returns status code 500, same goes for all status codes

Tools

Curl with proxy

You can run ./curl-proxy in this directory that has all the same params as curl but sends data via this proxy.

Example: ./curl-proxy -X POST http://google.com

Note: It won't work with HTTPS.

Throttling test

Run ./throttling-test.sh in order to verify the throttling you implemented is working properly. You should expect a lot of Too Many Requests and few successful requests

Postgres admin

Part of the docker-compose is adminer. To access it, go to localhost:9000 and fill in:

server: db
username: proxy
password: password
database: proxydb

tomasherman / intro-to-zio