如何在App Engine上使用go-sql-driver / mysql连接到Google Cloud SQL？

Question

I'm using the go-sql-driver/mysql driver in Go on App Engine to connect to a Cloud SQL instance like this:

import (
   "database/sql"
   _ "github.com/go-sql-driver/mysql"
)

db, dbErr := sql.Open("mysql", "root@cloudsql(project:instance)/database"
...
pingErr := db.Ping()

but I get "permission denied" in pingErr.

Of course, I've checked my app is authorized in the Cloud SQL console under "Access Control" per the docs. I also tried adding a MySQL user with privileges and using user:password in place of root and even not specifying a user.

What am I doing wrong?

...

Update:

Per @Kyle's suggestion I tried an alternate driver ziutek/mymysql and it works with the following code:

import (
   "database/sql"
   _ "github.com/ziutek/mymysql/godrv"
   _ "github.com/ziutek/mymysql/mysql"
   _ "github.com/ziutek/mymysql/native"
)

db, dbErr := sql.Open("mymysql", "cloudsql:project:instance*database/user/password"

Guess it's time for a pull request on go-sql-driver/mysql if I can figure out what's going wrong! Any insights or experience appreciated!

Answer 1

It's a versioning issue!

If you look carefully, App Engine support was added to the master branch but the latest release is 1.1 and doesn't include it.

Instead of go get github.com/go-sql-driver/mysql you need to manually git clone https://github.com/go-sql-driver/mysql (master branch) into $GOPATH/src/ and then deploy to App Engine!

This comment from the author is what tipped me off and @Kyle's suggestion to try another driver (which worked) motivated me to re-read everything again - thanks!