Build a Ruby App with CockroachDB and the Ruby pg Driver

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

Step 1. Start CockroachDB

Create a free 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 Create your cluster page, select Serverless.
Click Create cluster.

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

Create a SQL user

The Create SQL user dialog allows you to create a new SQL user and password.

Enter a username in the SQL user field or use the one provided by default.
Click Generate & save password.
Copy the generated password and save it in a secure location.
Click Next.

Currently, all new users are created with full privileges. For more information and to change the default settings, see [Manage SQL users on a cluster.

Get the root certificate

The Connect to cluster dialog shows information about how to connect to your cluster.

Select General connection string from the Select option dropdown.
Open a new terminal on your local machine, and run the CA Cert download command provided in the Download CA Cert section. The client driver used in this tutorial requires this certificate to connect to CockroachDB Cloud.

Get the connection string

Open the General connection string section, then copy the connection string provided and save it in a secure location.

Note:

The connection string is pre-populated with your username, password, cluster name, and other details. Your password, in particular, will be provided only once. Save it in a secure place (Cockroach Labs recommends a password manager) to connect to your cluster in the future. 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.

If you haven't already, download the CockroachDB binary.
Run the cockroach start-single-node command:
```
$ cockroach start-single-node --advertise-addr 'localhost' --insecure
```
This starts an insecure, single-node cluster.

Take note of the following connection information in the SQL shell welcome text:

CockroachDB node starting at 2021-08-30 17:25:30.06524 +0000 UTC (took 4.3s)
build:               CCL v21.1.6 @ 2021/07/20 15:33:43 (go1.15.11)
webui:               http://localhost:8080
sql:                 postgresql://root@localhost:26257?sslmode=disable

You'll use the sql connection string to connect to the cluster later in this tutorial.

Warning:

The --insecure flag used in this tutorial is intended for non-production testing only. To run CockroachDB in production, use a secure cluster instead.

Step 2. 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.

Step 3. Configure the dependencies

Install libpq for your platform.

For example, to install libpq on macOS with Homebrew, run the following command:
```
brew install libpq
```
Configure bundle to use libpq.

For example, if you installed libpq on macOS with Homebrew, run the following command from the hello-world-ruby-pg directory:
```
bundle config --local build.pg --with-opt-dir="{libpq-path}"
```
Where {libpq-path} is the full path to the libpq installation on your machine (e.g., /usr/local/opt/libpq).
Install the dependencies:
```
bundle install
```

Step 4. Run the code

Set the DATABASE_URL environment variable to the connection string to your CockroachDB Cloud cluster:
```
$ export DATABASE_URL="postgresql://root@localhost:26257?sslmode=disable"
```
```
$ export DATABASE_URL="{connection-string}"
```
Where {connection-string} is the connection string you obtained from the CockroachDB Cloud Console.
The app uses the connection string saved to the DATABASE_URL environment variable to connect to your cluster and execute the code.

Run the code to create a table and insert some rows:

ruby main.rb

The output should look similar to the following:

------------------------------------------------
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:

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