Cassandra Example Using Ruby

The purpose of this step-by-step tutorial is to provide a very simple example of configuring and using the Cassandra database engine with the Ruby Language.

Requirements

Docker Desktop 4.23.0 or newer
Rails >= 5.2.8.1 and < 6
Ruby >= 2.7.8 and < 3

Note: This tutorial was updated on macOS 13.5.2.

Communication

If you need help, use Stack Overflow. (Tag ‘cassandra’)
If you’d like to ask a general question, use Stack Overflow.
If you found a bug, open an issue.
If you have a feature request, open an issue.
If you want to contribute, submit a pull request.

Installation, Setup, and Usage

Open new terminal window
Create the project directory
```
mkdir blog
cd blog
```

Create docker-compose.yml file with the following content:

services:
  some-cassandra:
    image: cassandra:4.1.3
    container_name: some-cassandra
    environment:
      - CASSANDRA_CLUSTER_NAME=cassandra-cluster
    ports:
      - 9042:9042
    volumes:
      - cassandra-data:/var/lib/cassandra
volumes:
  cassandra-data: {}

Start a single node cluster
```
docker-compose up -d
```

Check the status of your cluster

docker-compose exec some-cassandra nodetool status

Note: One should see that the node status as Up Normal (UN) that looks similar to the following:

Datacenter: datacenter1
=======================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address     Load       Tokens       Owns    Host ID                               Rack
UN  172.19.0.2  582.5 KB   256          ?       e61cf276-c860-4990-bf03-37161414aed2  rack1
Note: Non-system keyspaces don't have the same replication settings, effective ownership information is meaningless

Generate a new Rails application

gem install rails -v '5.2.8.1'
rails _5.2.8.1_ new . ---skip-active-record --skip-active-storage -T --skip-bundle --skip-webpack-install --skip-javascript --no-rc

Add the Ruby cequel gem

bundle add i18n --version "= 1.8.11"
bundle add cequel
bundle add activemodel-serializers-xml

Generate scaffold of the application
```
rails g scaffold post title body
```
Add the following as the first route within config/routes.rb file:
```
root 'posts#index'
```

Create app/models/post.rb file with the following content:

class Post
  include Cequel::Record
  key :id, :timeuuid, auto: true
  column :title, :text
  column :body, :text
  timestamps
end

Create a default Cassandra configuration file
```
rails g cequel:configuration
```
Initialize Cassandra keyspace (database)
```
rails cequelcreate
```
Synchronize your Rails model schemas with Cassandra keyspace
```
rails cequel:migrate
```
Start the Rails server
```
rails s
```
Play with the application
```
open http://localhost:3000
```
Remove the keyspace
```
rails cequeldrop
```
Stop a single node cluster
```
docker-compose down
```

References

Support

Bug reports and feature requests can be filed for the cassandra-example-using-rails project here:

File Bug Reports and Features

Contact

Follow Conrad Taylor on Twitter (@conradwt)

Creator

Conrad Taylor (@conradwt)

License

This repository is released under the MIT License.