How to connect to Cloud-SQL from Cloud Function in Go?

Question

For a project i'm trying to connection a cloud function to a cloud sql database setup as described in this quickstart guide .

The function is configured in the same region, the service account has the Role Cloud SQL-Client . I called the function through my computer like this:

gcloud functions call <function-name> --region=<region> --data '{"recipient":"hello","requester":"hello","message":"test"}'

The connection to the function is working, it seems like just the authentication to the database doesn't work but i don't get where i failed.

I checked the password, user and connection name multiple times, reset the password and it still doesn't work. I found the issue here related to connecting cloud functions to cloud sql.

I tried surrounding the password in the dsn -string with single-quotes just to be sure escaping of characters in the password isn't a problem.

I also checked the environment variables coming in and they are the ones i entered in the configuration.

The function just pings the database for test purposes:

package receiver

import (
    "database/sql"
    "fmt"
    "net/http"
    "os"

    // Import Postgres SQL driver
    _ "github.com/lib/pq"
)

// Receives a message and stores it
func Receive(w http.ResponseWriter, r *http.Request) {
    connectionName := os.Getenv("POSTGRES_INSTANCE_CONNECTION_NAME")
    dbUser         := os.Getenv("POSTGRES_USER")
    dbPassword     := os.Getenv("POSTGRES_PASSWORD")
    dsn            := fmt.Sprintf("user=%s password='%s' host=/cloudsql/%s dbname=messages", dbUser, dbPassword, connectionName)

    var err error
    db, err := sql.Open("postgres", dsn)
    if err != nil {
        fmt.Fprintf(w, "Could not open db: %v \n", err)
    }

    // Only allow 1 connection to the database to avoid overloading
    db.SetMaxIdleConns(1)
    db.SetMaxOpenConns(1)
    defer db.Close()

    if pingerror := db.Ping(); pingerror != nil {
        fmt.Fprintf(w, "Failed to ping database: %s \n", pingerror)
        return
    }
}

The variable POSTGRES_INSTANCE_CONNECTION_NAME is formatted as described here as ProjectID:Region:InstanceID .

Expected is a success message or no error and i'm actually getting this message:

pq: password authentication failed for user "postgres" 

Note: I also created a function containing the demo code from here with my sql database settings and the error is the same. It seems like i missed some step while setting up the user or sql instance. But i can't find out which.

Answer 1

Feels strange to answer my own question but here it is: For some reason connecting with the postgres user doesn't work. Finally i created a new database user for the function and a password containing only alphanumeric characters.

Answer 2

The unix socket at /cloudsql/{connectionName} is only provided in the GCF runtime. When running locally, you either need change your connection string or use the Cloud SQL proxy to simulate a unix socket at the same path.