Unable to connect to postgresql using Go and pq - postgresql

Question

I'm trying to connect a Go application with postgresql.
The app import postgresql driver:
"crypto/tls"
"database/sql"
"fmt"
"log"
"os"
"os/signal"
...
_ "github.com/go-sql-driver/mysql"
_ "github.com/lib/pq"
_ "github.com/mattn/go-sqlite3"
and uses like it to connect to the database:
driver, cnxn := dbFromURI(dbURI)
db, err := sql.Open(driver, cnxn)
if err != nil {
panic(err)
}
and the dbFromUri method just split the info
func dbFromURI(uri string) (string, string) {
parts := strings.Split(uri, "://")
return parts[0], parts[1]
}
My URI works locally when i run the command : psql postgresql://user:user#172.20.0.1:5432/lcp
But in go i Go, I got
./lcpserver
2021/03/07 02:00:42 Reading config /root/lcp-server-install/lcp-home/config/config.yaml
panic: pq: SSL is not enabled on the server
I tried this URI for Go without success : psql postgresql://user:user#172.20.0.1:5432/lcp?sslmode=disable
Do you have any idea why i can't connect ?
I tried with my aws rds postgres database, and got same result. Thnaks for the help.
complete code of the server
https://github.com/readium/readium-lcp-server/blob/master/lcpserver/lcpserver.go
I change the typo and the demo provided i succeed the connexion. But in the lcp server i style got the same issue.
postgres://user:user#172.20.0.1:5432/lcp?sslmode=disable
EDIT 2:
The error is due to the fact that the script tries prepare command. I update the minimal example and it fails too.
package main
import (
"database/sql"
"fmt"
"strings"
_ "github.com/lib/pq"
)
func dbFromURI(uri string) (string, string) {
parts := strings.Split(uri, "://")
return parts[0], parts[1]
}
func main() {
driver, cnxn := dbFromURI("postgres://user:user#172.20.0.1:5432/lcp?sslmode=disable")
fmt.Println("The driver " + driver)
fmt.Println("The cnxn " + cnxn)
db, err := sql.Open(driver, cnxn)
_, err = db.Prepare("SELECT id,encryption_key,location,length,sha256,type FROM content WHERE id = ? LIMIT 1")
if err != nil {
fmt.Println("Prepare failed")
fmt.Println(err)
}
if err == nil {
fmt.Println("Successfully connected")
} else {
panic(err)
}
}
I got :
prepare failed
pq: SSL is not enabled on the server
2021/03/07 17:20:13 This panic 3
panic: pq: SSL is not enabled on the server

Answer 1

The first problem is a typo in the connection string: postgresql://user:user#172.20.0.1:5432/lcp?sslmode=disable. In Go code it should be postgres://user:user#172.20.0.1:5432/lcp?sslmode=disable.
We also need to pass the full connection string as the second argument to sql.Open. For now, the dbFromURI function returns user:user#172.20.0.1:5432/lcp?sslmode=disable, but we need postgres://user:user#172.20.0.1:5432/lcp?sslmode=disable, because pq is waiting for this prefix to parse it.
After fixing this, I was able to establish a connection using a minimal postgres client based on your code.
To try this yourself, start the server with the following command:
docker run --rm -p 5432:5432 -e POSTGRES_PASSWORD=some_password postgres
And try to connect using the following client code:
package main
import (
"database/sql"
"fmt"
_ "github.com/lib/pq"
)
func main() {
cnxn := "postgres://postgres:some_password#127.0.0.1:5432/lcp?sslmode=disable"
_, err := sql.Open("postgres", cnxn)
if err != nil {
panic(err)
}
_, err = db.Prepare("SELECT id,encryption_key,location,length,sha256,type FROM content WHERE id = ? LIMIT 1")
if err != nil {
fmt.Println("Prepare failed")
panic(err)
}
}