Build a Ruby App with CockroachDB and ActiveRecord

This tutorial shows you how build a simple Ruby application with CockroachDB and ActiveRecord. CockroachDB provides an ActiveRecord adapter for CockroachDB as a RubyGem.

Tip:

For a more realistic use of ActiveRecord with CockroachDB in a Rails app, see our examples-orms repository.

Step 1. Start CockroachDB

Choose whether to run a temporary local cluster or a free CockroachDB cluster on CockroachCloud. The instructions below will adjust accordingly.

  1. If you haven't already, download the CockroachDB binary.
  2. Run the cockroach demo command:

    icon/buttons/copy
    $ cockroach demo \
    --empty
    

    This starts a temporary, in-memory cluster and opens an interactive SQL shell to the cluster. Any changes to the database will not persist after the cluster is stopped.

  3. Take note of the (sql/tcp) connection string in the SQL shell welcome text:

    # Connection parameters:
    #   (console) http://127.0.0.1:61009
    #   (sql)     postgres://root:admin@?host=%2Fvar%2Ffolders%2Fk1%2Fr048yqpd7_9337rgxm9vb_gw0000gn%2FT%2Fdemo255013852&port=26257
    #   (sql/tcp) postgres://root:admin@127.0.0.1:61011?sslmode=require    
    

    In this example, the port number is 61011. You will use the port number in your application code later.

Create a free cluster

  1. If you haven't already, sign up for a CockroachCloud account.
  2. Log in to your CockroachCloud account.
  3. On the Clusters page, click Create Cluster.
  4. On the Create your cluster page, select the Free Plan.

    Note:

    This cluster will be free forever.

  5. (Optional) Select a cloud provider (GCP or AWS) in the Additional configuration section.

  6. Click Create your free cluster.

Your cluster will be created in approximately 20-30 seconds.

Set up your cluster connection

Once your cluster is created, the Connection info dialog displays. Use the information provided in the dialog to set up your cluster connection for the SQL user that was created by default:

  1. Click the name of the cc-ca.crt to download the CA certificate to your local machine.
  2. Create a certs directory on your local machine:

    icon/buttons/copy
    $ mkdir certs
    
  3. Move the downloaded cc-ca.crt file to the certs directory:

    icon/buttons/copy
    $ mv <path>/<to>/cc-ca.crt <path>/<to>/certs
    

    For example:

    icon/buttons/copy
    $ mv Users/maxroach/Downloads/cc-ca.crt Users/maxroach/certs
    
  4. Copy the connection string provided, which will be used in the next steps (and to connect to your cluster in the future).

    Warning:

    This connection string contains your password, which will be provided only once. If you forget your password, you can reset it by going to the SQL Users page.

Step 2. Create a database

  1. In the SQL shell, create the bank database that your application will use:

    icon/buttons/copy
    > CREATE DATABASE bank;
    
  2. Create a SQL user for your app:

    icon/buttons/copy
    > CREATE USER <username> WITH PASSWORD <password>;
    

    Take note of the username and password. You will use it in your application code later.

  3. Give the user the necessary permissions:

    icon/buttons/copy
    > GRANT ALL ON DATABASE bank TO <username>;
    
  1. If you haven't already, download the CockroachDB binary.
  2. Start the built-in SQL shell using the connection string you got from the CockroachCloud Console earlier:

    icon/buttons/copy
    $ cockroach sql \
    --url='postgres://<username>:<password>@<global host>:26257/<cluster_name>.defaultdb?sslmode=verify-full&sslrootcert=<certs_dir>/cc-ca.crt'
    

    In the connection string copied from the CockroachCloud Console, your username, password and cluster name are pre-populated. Replace the <certs_dir> placeholder with the path to the certs directory that you created earlier.

  3. In the SQL shell, create the bank database that your application will use:

    icon/buttons/copy
    > CREATE DATABASE bank;
    

Step 3. Get the code

Clone the code's GitHub repository.

icon/buttons/copy
git clone https://github.com/cockroachlabs/hello-world-ruby-activerecord

Check out the 5.2 branch:

icon/buttons/copy

git checkout 5.2

Check out the cockroachcloud branch:

icon/buttons/copy

git checkout cockroachcloud

Check out the cockroachcloud-5.2 branch:

icon/buttons/copy
git checkout cockroachcloud-5.2

Step 4. Configure the dependencies

  1. Install libpq for your platform. For example, to install it on Mac with Homebrew:

    icon/buttons/copy

    brew install libpq
    
  2. Configure bundle to use libpq. For example, if you installed libpq on Mac using Homebrew:

    icon/buttons/copy

    bundle config --local build.pg --with-opt-dir="/usr/local/opt/libpq"
    

    Set --with-opt-dir to the location of libpq on your OS.

Step 5. Install the dependencies

icon/buttons/copy
bundle install

Step 6. Update the connection parameters

Update the connection parameters to connect to your cluster.

icon/buttons/copy

ActiveRecord::Base.establish_connection(

  # Specify the CockroachDB ActiveRecord adapter
  adapter:     'cockroachdb',
  username:    'maxroach',
  password:    'password',
  database:    'bank',
  host:        'localhost',
  port:        26257,
  sslmode:     'require'

  #sslrootcert: 'certs/ca.crt'
)

Where {port} is the port number from the connection string you noted earlier, {username} is the database username you created, and {password} is the database user's password.

icon/buttons/copy

ActiveRecord::Base.establish_connection(

  # Specify the CockroachDB ActiveRecord adapter
  adapter:     'cockroachdb',
  username:    '{user}',
  password:    '{password}',
  database:    '{cluster_name}.bank',
  host:        '{globalhost}',
  port:        26257,
  sslmode:     'verify-full',
  sslrootcert: '{path to the CA certificate}'
)

Where:

  • {username} and {password} specify the SQL username and password that you created earlier.
  • {globalhost} is the name of the CockroachCloud Free (beta) host (e.g., free-tier.gcp-us-central1.cockroachlabs.cloud).
  • {path to the CA certificate} is the path to the cc-ca.crt file that you downloaded from the CockroachCloud Console.
  • {cluster_name} is the name of your cluster.
Note:

If you are using the connection string that you copied from the Connection info dialog, your username, password, hostname, and cluster name will be pre-populated.

Step 7. Run the Ruby code

Run the code to create a table and insert some rows, and then you'll run code to read and update values as an atomic transaction.

icon/buttons/copy
ruby main.rb

The output should be:

-- create_table(:accounts, {:force=>true, :id=>:integer})
   -> 0.3951s
account: 1 balance: 1000
account: 2 balance: 250

What's next?

Read more about using ActiveRecord, or check out a more realistic implementation of ActiveRecord with CockroachDB in a Rails app in our examples-orms repository.

You might also be interested in the following pages:

YesYes NoNo