coding-lagom

Some test with Lightbend's Lagom (www.lagomframework.com)

Prerequisites

• Docker (version 1.11 or later is installed and running).
• Docker Compose is installed. Docker Compose is installed by default with Docker for Mac. Docker memory is allocated minimally at 6 GB. (When using Docker Desktop for Mac, the default Docker memory allocation is 2 GB. You can change the default allocation to 6 GB in Docker. Navigate to Preferences > Resources > Advanced.)
• Internet connectivity
• (Optional) curl.

Set up a development/testings stand

If we don't want to (or cannot) use the sbt/maven plugins for lagom development we can use such approach (leas automatic, however more flexible):

• set up a kafka cluster (if we use it at all)
• set up a cassandra db (if we use it, and it is our choose of persistence backend)
• run our lagom app in cluster (with debug option or not)

Set up a kafka cluster

Download and Start Confluent Platform Using Docker

This in fact will install and run the full set of tools from Confluent Platform (Community version) (https://confluent.io) and sometimes can be considered as too much however if you use those extra tools it can be very handy for you.

1. Download or copy the contents of the Confluent Community all-in-one Docker Compose file:

curl --silent --output docker-compose.yml \
https://raw.githubusercontent.com/confluentinc/cp-all-in-one/6.2.0-post/cp-all-in-one-community/docker-compose.yml

2. Start Confluent Platform:

docker-compose up -d

3. Create a topic test:

docker-compose exec broker kafka-topics \
  --create \
  --bootstrap-server localhost:9092 \
  --replication-factor 1 \
  --partitions 1 \
  --topic test

4. Stop Confluent Containers and Clean Up:

docker-compose stop

# After stopping the Docker containers, run the following commands 
# to prune the Docker system. 
# Running these commands deletes containers, networks, 
# volumes, and images, freeing up disk space.
docker system prune -a --volumes --filter "label=io.confluent.docker"

Set up a cassandra db

1. Pull the latest image:

docker pull cassandra:latest

2. Run image (it will start a cassandra instance available on 9042/tcp port)

docker run -p 9042:9042 --name cassandra cassandra

If the default port should be replaced use such command

docker run -p 9043:9042 --name cassandra cassandra

3. Create a file with your DML like this:

-- Create a keyspace
CREATE KEYSPACE IF NOT EXISTS store WITH REPLICATION = { 'class' : 'SimpleStrategy', 'replication_factor' : '1' };

-- Create a table
CREATE TABLE IF NOT EXISTS store.shopping_cart (
userid text PRIMARY KEY,
item_count int,
last_update_timestamp timestamp
);

-- Insert some data
INSERT INTO store.shopping_cart
(userid, item_count, last_update_timestamp)
VALUES ('9876', 2, toTimeStamp(now()));
INSERT INTO store.shopping_cart
(userid, item_count, last_update_timestamp)
VALUES ('1234', 5, toTimeStamp(now()));

4. Connect to CQLSH :

docker exec -it cassandra /opt/cassandra/bin/cqlsh

5. type the content of the file from the step 3 into this shell.
6. Stop Cassandra and Clean Up:

docker kill cassandra
docker network rm cassandra

---

application.mode=prod java -Dhttp.port=9000 -Dakka.remote.artery.canonical.port=25520 -Dakka.management.http.port=8558 -Dpidfile.path="/dev/null" -jar service-a-impl-all.jar