How to connect to Google CloudSQL PostgresSQL - postgresql

Question

I tried to connect to Google CloudSQL PostgresSQL using Gorm golang and seems like it is not working.
Here's the code
func InitDB() *gorm.DB {
psqlInfo := fmt.Sprintf("host=%s port=%s user=%s password=%s dbname=%s sslmode=disable", os.Getenv("DB_HOST"), os.Getenv("DB_PORT"), os.Getenv("DB_USER"), os.Getenv("DB_PASSWORD"), os.Getenv("DB_NAME"))
db, err := gorm.Open("postgres", psqlInfo)
if err != nil {
fmt.Println("Failed to connect to the Database")
}
fmt.Println("Connected to the Database")
DB = db
return DB
}
If im using the localhost config everything works fine. See my .env file for cloudSQL config
DB_HOST=trader-234509:us-central1:testv1
DB_PORT=5432
DB_USER=username
DB_NAME=testv1
DB_PASSWORD=
Error is saying
dial tcp: lookup trader-234509:us-central1:testv1: no such host
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x40 pc=0x164681d]
My local config (This one works fine)
DB_HOST=localhost
DB_PORT=5432
DB_USER=username
DB_NAME=test
DB_PASSWORD=
Did i do anything wrong?

Answer 1

Here's roughly how I connect from AppEngine:
import (
_ "github.com/GoogleCloudPlatform/cloudsql-proxy/proxy/dialers/postgres"
"fmt"
"gorm.io/driver/postgres"
"gorm.io/gorm"
)
func New() (*gorm.DB, error) {
user := "theuser"
password := "apassword"
dbHost := "my-project:the-region:my-db-instance-name"
databaseName := "mydbname"
connString := fmt.Sprintf("host=%s user=%s dbname=%s sslmode=disable password=%s", dbHost, user, databaseName, password)
return gorm.Open(postgres.New(postgres.Config{
DriverName: "cloudsqlpostgres",
DSN: connString,
}))
}

Answer 2

Cloud SQL doesn't support direct connection to instance name for 3rd party application yet, for details: https://cloud.google.com/sql/docs/mysql/connect-external-app
Based on my experience, there are 2 solutions:
As per above instruction, you can setup a Cloud Proxy following the steps and the connections flow would be: Golang app -> Cloud Proxy -> Cloud SQL
This approach is flexible and you're able to control the connection using firewall.
But you have to spend extra $$ to maintain the server and this cloud proxy instance, I've also heard that the cloud proxy may have some performance issues but I don't have exact evidence so far
Assign a Private IP to the Cloud SQL instance, refer to https://cloud.google.com/sql/docs/mysql/private-ip, so that you application can access the DB directly using this IP.
The trade-off is obvious that the app must be in the same network of the project, but this is a much more convenient approach, esp. all your applications are hosted in the same network
I didn't try out the public IP access approach as Cloud Proxy is just what I need if remote network connection is needed
In short, you need to deploy your code in a VM or other Google Managed service using option 2, or setup the cloud proxy to support your local debugging for option 1
Hope it helps