CODEWITHSUNDEEP
postgresqldartgoogle-cloud-sqlgoogle-cloud-run
blas3nik
blas3nik

Reputation: 1381

How can I connect to a Cloud PostgreSQL database from dart code?

I have a PostgreSQL database deployed in Google Cloud that I am trying to connect to from a Cloud Run instance. I have tried the following two packages, both of them eventually leading to the same exception:

The exception I am getting is: SocketException: Failed host lookup: '/cloudsql/{INSTANCE_CONNECTION_NAME}' (OS Error: Name or service not known, errno = -2)

I get here both times when trying to establish the connection, so in the case of the first package:

connection = new PostgreSQLConnection(
        '/cloudsql/{INSTANCE_CONNECTION_NAME}',
        5432,
        'postgres',
        username: 'username',
        password: 'password');
await connection.open(); // <-- exception thrown here

I have tried changing the host string to /cloudsql/INSTANCE_CONNECTION_NAME}/.s.PGSQL.5432, but that did not work. My first thought were permissions, the service account the Cloud Run instance is using ([email protected]) has the Cloud SQL Editor role (tried Client and Admin too).

Running the same database code locally from a dart console app, I can connect to my database via its public IP address as the host with both packages, so the database itself is up and running.

Can someone point me in the right direction with this exception/have an example code for any of the packages above to show how to connect it to a Cloud SQL instance from a Cloud Run?

Edit: I tried setting up a proxy locally to test out if the connection is wrong like so:

.\cloud_sql_proxy.exe -instances={INSTANCE_CONNECTION_NAME}=tcp:5433 psql

Then changing the connection host value in the code to localhost, and the port to 5433. To my surprise it works - so from locally I am seemingly able to connect to the DB using that connection string. It still doesn't work when I use it from a Cloud Run instance though. Any help is appreciated!

Upvotes: 7

Views: 1291

Answers (4)

Zelkreps
Zelkreps

Reputation: 21

I was struggling with the same issue.

The solution is to create a connection as follows:

  PostgreSQLConnection getProdConnection() {
    final String connectionName = Platform.environment['CLOUD_SQL_CONNECTION_NAME']!;
    final String databaseName = Platform.environment['DB_NAME']!;
    final String user = Platform.environment['DB_USER']!;
    final String password = Platform.environment['DB_PASS']!;
    final String socketPath = '/cloudsql/$connectionName/.s.PGSQL.5432';

    return PostgreSQLConnection(
      socketPath,
      5432,
      databaseName,
      username: user,
      password: password,
      isUnixSocket: true,
    );
  }

Then when you create a Cloud Run service, you need to define 'Enviroment variables' as follows.

enter image description here

You also need to select your sql instance in the 'connections' tab.

enter image description here

Then the last thing needed is to configure a Cloud Run service account.

enter image description here

Then the connection to instance should be successful and there should no longer be a need for a 0.0.0.0/0 connection.

However, if you try to run this connection locally on a Windows device during development the connection will not be allowed and you will be presented with this error message: 'Unix domain sockets are not available on this operating system.'

Therefore, I recommend that you open Google SQL networking to your public address and define a local environment using the 'Public IP address' of your SQL instance.

For more information on this topic, I can recommend these resources that have guided me to the right solution:

Upvotes: 0

Suragch
Suragch

Reputation: 512566

Not having actually tested this myself, according to the source code of the postgres package, you have to specify that you want a Unix socket:

connection = PostgreSQLConnection(
  ...
  isUnixSocket: true, //              <-- here
);

The default is false.

The host you pass is must also be valid. The docs say:

[host] must be a hostname, e.g. "foobar.com" or IP address. Do not include scheme or port.

Upvotes: 0

blas3nik
blas3nik

Reputation: 1381

Just for those who come across this question in the future: as it stands right now, I had to resort to the suggestion posted by Daniele Ricci and use the public IP for the database. The one thing to point out here was that since Cloud Runs don't have a static IPv4 address to run from, the DB had to be set to allow connections from anywhere (had to add an authorized connection from 0.0.0.0/0), which is unsafe. Until the kind development team of dart figures out how to use UNIX sockets, this seems to be the only way of getting it to work.

Upvotes: 1

Daniele Ricci
Daniele Ricci

Reputation: 15837

It seems dart doesn't support connection through unix socket, you need to configure a IP (public or private, as you need).

Alternatively you can use pg which support unix socket connection

Hope this helps.

Upvotes: 3

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