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

1. Open new terminal window

2. Create the project directory

   mkdir blog
   cd blog

3. 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: {}

4. Start a single node cluster

   docker-compose up -d

5. 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
   

6. 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

7. Add the Ruby cequel gem

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

8. Generate scaffold of the application

   rails g scaffold post title body

9. Add the following as the first route within config/routes.rb file:

   root 'posts#index'

10. 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

11. Create a default Cassandra configuration file

    rails g cequel:configuration

12. Initialize Cassandra keyspace (database)

    rails cequel:keyspace:create

13. Synchronize your Rails model schemas with Cassandra keyspace

    rails cequel:migrate

14. Start the Rails server

    rails s

15. Play with the application

    open http://localhost:3000

16. Remove the keyspace

    rails cequel:keyspace:drop

17. Stop a single node cluster

    docker-compose down

---

References

• Apache Cassandra

• Cequel

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.

Copyright

© Copyright 2014 - 2023 Conrad Taylor. All Rights Reserved.