Build a Go application
The following tutorial shows a small Go application that connects to a YugabyteDB cluster using the Go PostgreSQL driver and performs basic SQL operations. Use the application as a template to get started with Yugabyte Cloud in Go.
Prerequisites
In addition to Go (tested with version 1.17.6), this tutorial requires the following.
Yugabyte Cloud
- You have a cluster deployed in Yugabyte Cloud. To get started, use the Quick start.
- You downloaded the cluster CA certificate. Refer to Download your cluster certificate.
- You have added your computer to the cluster IP allow list. Refer to Assign IP Allow Lists.
Clone the application from GitHub
Clone the sample application to your computer:
git clone https://github.com/yugabyte/yugabyte-simple-go-app.git && cd yugabyte-simple-go-app
Provide connection parameters
The application needs to establish a connection to the YugabyteDB cluster. To do this:
-
Open the
sample-app.gofile. -
Set the following configuration parameter constants:
- host - the host name of your YugabyteDB cluster. To obtain a Yugabyte Cloud cluster host name, sign in to Yugabyte Cloud, select your cluster on the Clusters page, and click Settings. The host is displayed under Network Access.
- port - the port number that will be used by the driver (the default YugabyteDB YSQL port is 5433).
- dbName - the name of the database you are connecting to (the default database is named
yugabyte). - dbUser and dbPassword - the username and password for the YugabyteDB database. If you are using the credentials you created when deploying a cluster in Yugabyte Cloud, these can be found in the credentials file you downloaded.
- sslMode - the SSL mode to use. Yugabyte Cloud requires SSL connections; use
verify-full. - sslRootCert - the full path to the Yugabyte Cloud cluster CA certificate.
-
Save the file.
Build and run the application
First, initialize the GO111MODULE variable.
$ export GO111MODULE=auto
Import the Go PostgreSQL driver.
$ go get github.com/lib/pq
Start the application.
$ go run sample-app.go
You should see output similar to the following:
>>>> Successfully connected to YugabyteDB!
>>>> Successfully created table DemoAccount.
>>>> Selecting accounts:
name = Jessica, age = 28, country = USA, balance = 10000
name = John, age = 28, country = Canada, balance = 9000
>>>> Transferred 800 between accounts.
>>>> Selecting accounts:
name = Jessica, age = 28, country = USA, balance = 9200
name = John, age = 28, country = Canada, balance = 9800
You have successfully executed a basic Go application that works with Yugabyte Cloud.
Explore the application logic
Open the sample-app.go file in the yugabyte-simple-go-app folder to review the methods.
main
The main method establishes a connection with your cluster via the Go PostgreSQL driver.
psqlInfo := fmt.Sprintf("host=%s port=%d user=%s password=%s dbname=%s",
host, port, dbUser, dbPassword, dbName)
if sslMode != "" {
psqlInfo += fmt.Sprintf(" sslmode=%s", sslMode)
if sslRootCert != "" {
psqlInfo += fmt.Sprintf(" sslrootcert=%s", sslRootCert)
}
}
db, err := sql.Open("postgres", psqlInfo)
createDatabase
The createDatabase method uses PostgreSQL-compliant DDL commands to create a sample database.
Statement stmt = conn.createStatement();
stmt := `DROP TABLE IF EXISTS DemoAccount`
_, err := db.Exec(stmt)
checkIfError(err)
stmt = `CREATE TABLE DemoAccount (
id int PRIMARY KEY,
name varchar,
age int,
country varchar,
balance int)`
_, err = db.Exec(stmt)
checkIfError(err)
stmt = `INSERT INTO DemoAccount VALUES
(1, 'Jessica', 28, 'USA', 10000),
(2, 'John', 28, 'Canada', 9000)`
_, err = db.Exec(stmt)
checkIfError(err)
selectAccounts
The selectAccounts method queries your distributed data using the SQL SELECT statement.
rows, err := db.Query("SELECT name, age, country, balance FROM DemoAccount")
checkIfError(err)
defer rows.Close()
var name, country string
var age, balance int
for rows.Next() {
err = rows.Scan(&name, &age, &country, &balance)
checkIfError(err)
fmt.Printf("name = %s, age = %v, country = %s, balance = %v\n",
name, age, country, balance)
}
transferMoneyBetweenAccounts
The transferMoneyBetweenAccounts method updates your data consistently with distributed transactions.
tx, err := db.Begin()
checkIfError(err)
_, err = tx.Exec(`UPDATE DemoAccount SET balance = balance - $1 WHERE name = 'Jessica'`, amount)
if checkIfTxAborted(err) {
return
}
_, err = tx.Exec(`UPDATE DemoAccount SET balance = balance + $1 WHERE name = 'John'`, amount)
if checkIfTxAborted(err) {
return
}
err = tx.Commit()
if checkIfTxAborted(err) {
return
}