Can not connect to PostgreSQL behind a tunnel

[Zeboton]

I did exactly like in the documentation, but Terraform returned an error.

Tunnel:

module "tunnel" {
  source  = "flaupretre/tunnel/ssh"
  version = "2.0.4"

  gateway_host = aws_instance.app_ec2.public_ip

  target_host = module.rds_postgresql.db_instance_address
  target_port = module.rds_postgresql.db_instance_port

  ssh_cmd = "ssh -o StrictHostKeyChecking=no -o PasswordAuthentication=no -i ${var.PRIVATE_KEY_PATH}"
}

Connection and working with DB. If I use a commented string then I get an error like dial tcp 127.0.0.1:22882:5432: connect: connection refused.

provider "postgresql" {
  alias           = "master"
  # host            = "${module.tunnel.host}:${module.tunnel.port}"
  host            = module.tunnel.host
  port            = module.tunnel.port
  username        = local.db.app.username
  password        = local.db.app.password
  database        = local.db.app.name
  sslmode         = "require"
  connect_timeout = 15
}

resource "postgresql_role" "pg_role" {
  provider = postgresql.master
  name     = local.db.app_db.username
  password = local.db.app_db.password
  login    = true
}

resource "postgresql_database" "pg_db" {
  provider = postgresql.master
  name     = local.db.app_db.name
  owner    = local.db.app_db.username
}

And I get an error:

╷
│ Error: Error connecting to PostgreSQL server 127.0.0.1 (scheme: postgres): dial tcp 127.0.0.1:22882: connect: connection refused
│ 
│   with postgresql_role.pg_role,
│   on rds-postgresql.tf line 107, in resource "postgresql_role" "pg_role":
│  107: resource "postgresql_role" "pg_role" {
│ 
╵
╷
│ Error: Error connecting to PostgreSQL server 127.0.0.1 (scheme: postgres): dial tcp 127.0.0.1:22882: connect: connection refused
│ 
│   with postgresql_database.pg_db,
│   on rds-postgresql.tf line 114, in resource "postgresql_database" "pg_db":
│  114: resource "postgresql_database" "pg_db" {
│ 
╵

I have a project in a container on this server ( gateway_host ) that has a connection to this PostgreSQL instance.

[Zeboton]

I have found the solution.

If a user for SSH isn't present then will be used the username of a current local user for connection. Obviously, the user's name on my machine is different than in an EC2 instance.

So using gateway_user = local.ec2.user is required for a successful connection. Initializing the module must be as follows:

module "tunnel" {
  source  = "flaupretre/tunnel/ssh"
  version = "2.0.4"

  gateway_host = aws_instance.app_ec2.public_ip
  gateway_user = local.ec2.user # <---- I added this string!

  target_host = module.rds_postgresql.db_instance_address
  target_port = module.rds_postgresql.db_instance_port

  ssh_cmd = "ssh -o StrictHostKeyChecking=no -o PasswordAuthentication=no -i ${var.PRIVATE_KEY_PATH}"
}

But why the module doesn't show an error that a tunnel was not established? Terraform returns an error right after trying a tunnel. It's very weird and confusing.

@flaupretre , please add the gateway_user parameter to the examples.