Build a Ruby App with CockroachDB and the Ruby pg Driver

On this page

Warning:

CockroachDB v21.1 is no longer supported. For more details, see the Release Support Policy.

This tutorial shows you how build a simple Ruby application with CockroachDB and the Ruby pg driver.

Step 1. Start CockroachDB

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

Create a free cluster

Note:

Organizations without billing information on file can only create one CockroachDB Serverless cluster.

If you haven't already, sign up for a CockroachDB Cloud account.
Log in to your CockroachDB Cloud account.
On the Clusters page, click Create Cluster.
On the Select a plan page, select Serverless.
On the Cloud & Regions page, select a cloud provider (GCP or AWS) in the Cloud provider section.
In the Regions section, select a region for the cluster. Refer to CockroachDB Cloud Regions for the regions where CockroachDB Serverless clusters can be deployed. To create a multi-region cluster, click Add region and select additional regions. A cluster can have at most six regions.
Click Next: Capacity.
On the Capacity page, select Start for free. Click Next: Finalize.
On the Finalize page, click Create cluster.

Your cluster will be created in a few seconds and the Create SQL user dialog will display.

Set up your cluster connection

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

In your terminal, run the second command from the dialog to create a new certs directory on your local machine and download the CA certificate to that directory:
```
curl --create-dirs -o ~/.postgresql/root.crt -O https://cockroachlabs.cloud/clusters/<cluster-id>/cert
```
Your cert file will be downloaded to ~/.postgresql/root.crt.
```
curl --create-dirs -o ~/.postgresql/root.crt -O https://cockroachlabs.cloud/clusters/<cluster-id>/cert
```
Your cert file will be downloaded to ~/.postgresql/root.crt.
```
mkdir -p $env:appdata\.postgresql\; Invoke-WebRequest -Uri https://cockroachlabs.cloud/clusters/<cluster-id>/cert -OutFile $env:appdata\.postgresql\root.crt
```
Your cert file will be downloaded to %APPDATA%/.postgresql/root.crt.
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 for the cluster, found at https://cockroachlabs.cloud/cluster/<CLUSTER ID>/users.
```
cockroach sql --url 'postgresql://<username>:<password>@<serverless-host>:26257/defaultdb?sslmode=verify-full&sslrootcert='$HOME'/.postgresql/root.crt'
```
```
cockroach sql --url 'postgresql://<username>:<password>@<serverless-host>:26257/defaultdb?sslmode=verify-full&sslrootcert='$HOME'/.postgresql/root.crt'
```
```
cockroach sql --url "postgresql://<username>:<password>@<serverless-host>:26257/defaultdb?sslmode=verify-full&sslrootcert=$env:appdata/.postgresql/root.crt"
```
Where:
- <username> is the SQL user. By default, this is your CockroachDB Cloud account username.
- <password> is the password for the SQL user. The password will be shown only once in the Connection info dialog after creating the cluster.
- <serverless-host> is the hostname of the CockroachDB Serverless cluster.
- <cluster-id> is a unique string used to identify your cluster when downloading the CA certificate. For example, 12a3bcde-4fa5-6789-1234-56bc7890d123.
You can find these settings in the Connection parameters tab of the Connection info dialog.

If you haven't already, download the CockroachDB binary.
Run the cockroach demo command:
```
$ cockroach demo \
--no-example-database
```
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.

Note:

If cockroach demo fails due to SSL authentication, make sure you have cleared any previously downloaded CA certificates from the directory ~/.postgresql.

Take note of the (sql) connection string in the SQL shell welcome text:

# Connection parameters:
#   (webui)    http://127.0.0.1:8080/demologin?password=demo76950&username=demo
#   (sql)      postgres://demo:demo76950@127.0.0.1:26257?sslmode=require
#   (sql/unix) postgres://demo:demo76950@?host=%2Fvar%2Ffolders%2Fc8%2Fb_q93vjj0ybfz0fz0z8vy9zc0000gp%2FT%2Fdemo070856957&port=26257

Step 2. Create a database

In the SQL shell, create the bank database that your application will use:
```
> CREATE DATABASE bank;
```
Create a SQL user for your app:
```
> CREATE USER <username> WITH PASSWORD <password>;
```
Take note of the username and password. You will use it in your application code later.
Give the user the necessary permissions:
```
> GRANT ALL ON DATABASE bank TO <username>;
```

If you haven't already, download the CockroachDB binary.
Start the built-in SQL shell using the connection string you got from the CockroachDB Cloud Console earlier:
```
$ 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 CockroachDB Cloud 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.
In the SQL shell, create the bank database that your application will use:
```
> CREATE DATABASE bank;
```
Exit the SQL shell:
```
> \q
```

Step 3. Get the code

Clone the code's GitHub repository.

git clone https://github.com/cockroachlabs/hello-world-ruby-pg

The code connects as the user you created and executes some basic SQL statements: creating a table, inserting rows, and reading and printing the rows.

Check out the cockroachcloud branch:

git checkout cockroachcloud

Step 4. Configure the dependencies

Install libpq for your platform. For example, to install it on Mac with Homebrew:
```
brew install libpq
```
Configure bundle to use libpq. For example, if you installed libpq on Mac using Homebrew:
```
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

bundle install

Step 6. Update the connection parameters

Update the connection parameters to connect to your cluster.


  conn = PG.connect(ENV['DATABASE_URL'])

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.


  conn = PG.connect(
    user: '{username}',
    password: '{password}',
    dbname: '{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 Serverless 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 CockroachDB Cloud Console.
{cluster_name} is the name of your cluster.

Note:

If you are using the connection string that you copied from the Connection info modal, 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.

ruby main.rb

The output should be:

------------------------------------------------
print_balances(): Balances as of '2021-02-23 11:56:54 -0800':
{"id"=>"1", "balance"=>"1000"}
{"id"=>"2", "balance"=>"250"}
------------------------------------------------
transfer_funds(): Trying to transfer 100 from account 1 to account 2
------------------------------------------------
print_balances(): Balances as of '2021-02-23 11:56:55 -0800':
{"id"=>"1", "balance"=>"900"}
{"id"=>"2", "balance"=>"350"}

What's next?

Read more about using the Ruby pg driver.

You might also be interested in the following pages:

Was this helpful?

Cockroach
University

Docs Hub

Build a Ruby App with CockroachDB and the Ruby pg Driver

Step 1. Start CockroachDB

Create a free cluster

Set up your cluster connection

Step 2. Create a database

Step 3. Get the code

Step 4. Configure the dependencies

Step 5. Install the dependencies

Step 6. Update the connection parameters

Step 7. Run the Ruby code

What's next?

Cockroach University

Docs Hub

Cockroach University

Docs Hub

Build a Ruby App with CockroachDB and the Ruby pg Driver

Step 1. Start CockroachDB

Create a free cluster

Set up your cluster connection

Step 2. Create a database

Step 3. Get the code

Step 4. Configure the dependencies

Step 5. Install the dependencies

Step 6. Update the connection parameters

Step 7. Run the Ruby code

What's next?

Cockroach
University

Cockroach
University