Cloud SQL for PostgreSQL on Google App Engine

GoDoc

Disclaimer

This is not a Google product, and is unsupported.

It uses the google.golang.org/appengine/cloudsql package, which is supported for MySQL, but not for Postgres.

It happens to work right now, but may not forever.

Example

app.yaml

runtime: go
api_version: go1

handlers:
- url: /.*
  script: _go_app

env_variables:
  # Replace INSTANCE_CONNECTION_NAME with the value obtained when configuring your
  # Cloud SQL instance, available from the Google Cloud Console or from the Cloud SDK.
  # For Cloud SQL 2nd generation instances, this should be in the form of "project:region:instance".
  CLOUDSQL_CONNECTION_NAME: 'INSTANCE_CONNECTION_NAME'
  # Replace username and password if you aren't using the root user.
  CLOUDSQL_USER: postgres
  CLOUDSQL_PASSWORD: pw

cloudsql.go

// Copyright 2017 Google Inc. All rights reserved.
// Use of this source code is governed by the Apache 2.0
// license that can be found in the LICENSE file.

// Sample cloudsql_postgres demonstrates connection to a Cloud SQL for Postgres instance from App Engine standard.
package main

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

	"google.golang.org/appengine"

	_ "github.com/broady/gae-postgres"
)

var db *sql.DB

func main() {
	var (
		connectionName = mustGetenv("CLOUDSQL_CONNECTION_NAME")
		user           = mustGetenv("CLOUDSQL_USER")
		password       = os.Getenv("CLOUDSQL_PASSWORD") // NOTE: password may be empty
	)

	var err error
	db, err = sql.Open("gae-postgres", fmt.Sprintf("cloudsql=%s user=%s password='%s'", connectionName, user, password))
	if err != nil {
		log.Fatalf("Could not open db: %v", err)
	}

	http.HandleFunc("/", handler)
	appengine.Main()
}

func handler(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path != "/" {
		http.NotFound(w, r)
		return
	}

	w.Header().Set("Content-Type", "text/plain")

	rows, err := db.Query("SELECT datname FROM pg_database")
	if err != nil {
		http.Error(w, fmt.Sprintf("Could not query db: %v", err), 500)
		return
	}
	defer rows.Close()

	buf := bytes.NewBufferString("Databases:\n")
	for rows.Next() {
		var dbName string
		if err := rows.Scan(&dbName); err != nil {
			http.Error(w, fmt.Sprintf("Could not scan result: %v", err), 500)
			return
		}
		fmt.Fprintf(buf, "- %s\n", dbName)
	}
	w.Write(buf.Bytes())
}

func mustGetenv(k string) string {
	v := os.Getenv(k)
	if v == "" {
		log.Panicf("%s environment variable not set.", k)
	}
	return v
}