Awesome
distage example
Example distage
project.
Features distage for dependency injection, BIO typeclasses for bifunctor tagless final, distage-testkit for testing, ZIO Environment for composing test fixtures, and distage-framework-docker for setting up test containers.
There are three variants of the example project:
- bifunctor-tagless – Main example. It's written in bifunctor tagless final style with BIO typeclasses, uses ZIO as a runtime and ZIO Environment for composing test fixtures.
- monofunctor-tagless – Written in monofunctor tagless final style with Cats Effect typeclasses, and can run using both Cats IO and ZIO runtimes.
- monomorphic-cats – A simpler example written without tagless final, uses Cats IO directly everywhere.
To launch tests that require postgres ensure you have a docker
daemon running in the background.
Use sbt test
to launch the tests.
You can launch the application with the following command.
# With docker daemon running
./launcher -u scene:managed :leaderboard
# Alternatively, with in-memory storage
./launcher -u repo:dummy :leaderboard
Afterwards you can call the HTTP methods:
curl -X POST http://localhost:8080/ladder/50753a00-5e2e-4a2f-94b0-e6721b0a3cc4/100
curl -X POST http://localhost:8080/profile/50753a00-5e2e-4a2f-94b0-e6721b0a3cc4 -d '{"name": "Kai", "description": "S C A L A"}'
# check leaderboard
curl -X GET http://localhost:8080/ladder
# user profile now shows the rank in the ladder along with profile data
curl -X GET http://localhost:8080/profile/50753a00-5e2e-4a2f-94b0-e6721b0a3cc4
Note
If ./launcher
command fails for you with some cryptic stack trace, there's most likely an issue with your Docker. First of all, check that you have docker
and contrainerd
daemons running. If you're using something else than Ubuntu, please stick to the relevant installation page:
sudo systemctl status docker
sudo systemctl status contrainerd
Both of them should have Active: active (running)
status. If your problem isn't gone yet, most likely you don't have your user in docker
group. Here you can find a tutorial on how to do so. Don't forget to log out of your session or restart your virtual machine before proceeding. If you still have problems, don't hesitate to open an issue.
Videos:
- Functional Scala 2019 – Hyperpragmatic Pure FP testing with distage-testkit
- ScalaWAW Warsaw Meetup – Livecoding this project
- Source Talks — Pragmatic Pure FP approach to application design and testing with distage
GraalVM Native Image
Use sbt
to build a native Linux binary with GraalVM NativeImage under Docker:
sbt bifunctor-tagless/GraalVMNativeImage/packageBin
If you want to build the app using local native-image
executable (e.g. on a Mac), comment out the graalVMNativeImageGraalVersion
key in build.sbt
first.
To test the native app with dummy repositories run:
./bifunctor-tagless/target/graalvm-native-image/bifunctor-tagless -u scene:managed -u repo:dummy :leaderboard
To test the native app with production repositories in Docker run:
./bifunctor-tagless/target/graalvm-native-image/bifunctor-tagless -u scene:managed -u repo:prod :leaderboard
Notes:
- Currently, the application builds with GraalVM
22.3
. Check other GraalVM images here - JNA libraries are just regular Java resources, currently the NI config is generated for x86-64 Linux, you'll have to re-generate or manually edit it to run on different operating systems or architectures.
- The following bugs may still manifest, but it seems like they aren't blockers anymore:
-Djna.debug_load=true
key added to the native app command line might help to debug JNA-related issues
Assisted NI configuration generator
See Native Image docs for details.
Add the following to Java commandline to run the Assisted configuration agent:
-agentlib:native-image-agent=access-filter-file=./ni-filter.json,config-output-dir=./src/main/resources/META-INF/native-image/auto-wip
Notes:
- The codepaths in
docker-java
are different for the cold state (when no containers are running) and the hot state. It seems like we've managed to build an exhaustive ruleset fordocker-java
so it's excluded inni-filter.json
. If something is wrong and you need to generate the rules fordocker-java
, run the agent twice in both hot and cold state. - Only
PluginConfig.const
works reliably under Native Image. So, ClassGraph analysis is disabled inni-filter.json
. You can't make dynamic plugin resolution working under Native Image.