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 YugabyteDB Managed in Go.
Prerequisites
Go (tested with version 1.17.6).
Clone the application from GitHub
Clone the sample application to your computer:
git clone https://github.com/YugabyteDB-Samples/yugabyte-simple-go-app.git && cd yugabyte-simple-go-app
Provide connection parameters
If your cluster is running on YugabyteDB Managed, you need to modify the connection parameters so that the application can establish a connection to the YugabyteDB cluster. (You can skip this step if your cluster is running locally and listening on 127.0.0.1:5433.)
To do this:
-
Open the
sample-app.go
file. -
Set the following configuration parameter constants:
- host - the host name of your YugabyteDB cluster. For local clusters, use the default (127.0.0.1). For YugabyteDB Managed, select your cluster on the Clusters page, and click Settings. The host is displayed under Connection Parameters.
- port - the port number for the driver to use (the default YugabyteDB YSQL port is 5433).
- dbName - the name of the database you are connecting to (the default is
yugabyte
). - dbUser and dbPassword - the username and password for the YugabyteDB database. For local clusters, use the defaults (
yugabyte
andyugabyte
). For YugabyteDB Managed, use the credentials in the credentials file you downloaded. - sslMode - the SSL mode to use. YugabyteDB Managed requires SSL connections; use
verify-full
. - sslRootCert - the full path to the YugabyteDB Managed 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 YugabyteDB Managed.
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
}