Degressly is a portmanteau of "Deterministic Regression". Inspired by opendiffy/diffy, degressly aims to create a scalable framework for performing regression testing.

Degressly works by running three parallel instances of your code side by side and multicasting all inbound requests to all three instances. The primary and secondary instances run your last known good code, while the candidate instances runs code that is to be tested. Differences between primary and candidate instances involve noise from non-deterministic sources like random number generation and timestamps, these differences are ignored based on the differences obtained from responses of primary and secondary instances. This allows you to perform black-box testing of your code without needing to write any tests, or mocking data that is a representative sample of your production environment.

If you want a quick and dirty way to try out degressly with a sample application, check out degressly/degressly-demo.

• In-depth analysis of differences in behaviour between new and old code. Including:
  • Differences in API Responses.
  • Differences in API requests made by the microservice.
  • Differences in data stored in the datastore.
• Filtering out noise from non-deterministic sources like random number generation and timestamps.
• Native support for replaying requests.
• Support for non-idempotent upstream APIs where each request must be sent once and once only.
  • Support for trapping all upstream calls when replaying requests.

The degressly ecosystem depends on the following repositories:

Clone repository:

git clone https://github.com/degressly/degressly-core.git
cd degressly-core

docker build -f Dockerfile -t degressly-core:latest
docker run -p8000:8000 degressly-core:latest

Create .env file:

touch .env
nano .env

Sample .env file:

primary_host=http://host.docker.internal:9000
secondary_host=http://host.docker.internal:9001
candidate_host=http://host.docker.internal:9002

Note on host names: https://docs.docker.com/desktop/networking/#i-want-to-connect-from-a-container-to-a-service-on-the-host

docker build -f Dockerfile -t degressly-core:latest
docker compose up

Clone all repos and build docker images:

git clone https://github.com/degressly/degressly-core.git
git clone https://github.com/degressly/degressly-comparator.git
git clone https://github.com/degressly/degressly-downstream.git
docker build degressly-core/ -t degressly-core:latest 
docker build degressly-comparator/ -t degressly-comparator:latest 
docker build degressly-downstream/ -t degressly-downstream:latest 
cd degressly-core

Create .env file:

touch .env

spring_profiles_active=mongo
diff_publisher_bootstrap_servers=kafka:9092
diff_publisher_topic_name=diff_stream
primary_host=http://host.docker.internal:9000
secondary_host=http://host.docker.internal:9001
candidate_host=http://host.docker.internal:9002
MONGO_URL=<mongo_cluster_url>/<mongo_db_name>
MONGO_USERNAME=<mongo_username>
MONGO_PASSWORD=<mongo_password>
MONGO_DBNAME=<mongo_db_name>

Note on host names: https://docs.docker.com/desktop/networking/#i-want-to-connect-from-a-container-to-a-service-on-the-host

Run containers

docker compose --profile full up

In no particular order:

• DB layer observation recon (comparator can consume from debezium or similar CDC pipeline).
• DB Proxy...?
• Performance regression tracking.
• Dockerization.
• Documentation for Replay support.

If you would like to reach out for support or feature requests, feel free to drop an email at [email protected]