driver: the driver shouldn't touch the application enviroment variables

[giautm]

When using the AutoConfigEmulator=true parameter, the driver set the SPANNER_EMULATOR_HOST env automaticly. This is causing issue when the application need two containers for its need.

go-sql-spanner/emulator_util.go

Lines 34 to 36 in e2620e6

	if err := os.Setenv("SPANNER_EMULATOR_HOST", host); err != nil {
	return err
	}

On the JDBC implement, the driver also doesn't touch application's env:

https://github.com/search?q=repo%3Agoogleapis%2Fjava-spanner-jdbc+SPANNER_EMULATOR_HOST&type=code

[rahul2393]

@giautm, Can you elaborate more on "when the application needs two containers"
In the connection string, there is an optional host value which you can pass for AutoConfigEmulator to use.

[giautm]

@giautm, Can you elaborate more on "when the application needs two containers" In the connection string, there is an optional host value which you can pass for AutoConfigEmulator to use.

Hello. I'm working on ariga/atlas, which is allow the user spin up containers via the connection URL like docker://spanner to use as the temporary database (DevDB - in Atlas' term) to apply schema migrations on it before apply it on production database.

When the user user docker, and their real database. The side-effect from AutoConfigEmulator also affect to the client that will used to connect to their production database (one running on Google Cloud) - currently, we have to workaround by unset this environment variable. But honestly, it look a bit dirty.

So, I suggest to just remove this side-effect on the Go driver, it also keep behavior consistent with the JDBC driver.

P/s: I also need your help to review my PR on Google Cloud Go to disable gRPC - It's adding 11MB in total. :D

[giautm]

Hello @rahul2393 Can I have a review there?

[rahul2393]

Hello @giautm,
But can we not just change the connection string without using env to configure whether to use emulator or not.
Example:
to connect to Emulator I can use

localhost:9010/projects/my-project/instances/my-project/databases/my-database?usePlainText=true;

to connect to real spanner db I just need to use

projects/my-project/instances/my-project/databases/my-database;

[giautm]

It doesn't work in our case. Because we have two calls to sql.Open in the same application, the first call sql.Open() to the dev-db with emulator will effect to the second call to sql.Open with real database.

[giautm]

To be clear, the AutoConfigEmulator=true causing conflict here. Without using it, the database is running fine. But we have to setup the database / instance by ourself, which isn't convenient.

[rahul2393]

Yes, and I wanted to see if you can just not use AutoConfigEmulator=true and just use host parameter in connection string to decide

localhost:9010/projects/my-project/instances/my-project/databases/my-database?usePlainText=true;

driver will connect to emulator running on 9010 port without SSL authentication.

[giautm]

Yeah, that just works fine. So what I suggest here is removing the call to os.Setenv(). This behavior only exists in the Go driver.