I am new to Terraform and Google Cloud.

I am trying to create a K8 cluster where pods inside the cluster could communicate with a Postgres server I have within the same VPC.

However, when I try to connect to the server using a psql client within a ubuntu pod inside the cluster using psql -h <PRIVATE_IP_OF_POSTGRES_SERVER> -U postgresadmin, it waits for a long time and throws the following timeout error.

psql: could not connect to server: Connection timed out
        Is the server running on host "<PRIVATE_IP_OF_POSTGRES_SERVER>" and accepting
        TCP/IP connections on port 5432?

I even tried to telnet <PRIVATE_IP_OF_POSTGRES_SERVER> and that is also not working. (PING is not working as well)

Here is my terraform script for creating the VPC and the K8 cluster:

variable "project_id" {
  description = "project id"
}

variable "region" {
  description = "region"
}

variable "gke_username" {
  default     = ""
  description = "gke username"
}

variable "gke_password" {
  default     = ""
  description = "gke password"
}

variable "gke_num_nodes" {
  default     = 1
  description = "number of gke nodes"
}

provider "google" {
  project = var.project_id
  region  = var.region
}

# VPC
resource "google_compute_network" "vpc" {
  name                    = "${var.project_id}-vpc"
  auto_create_subnetworks = "false"
}

# Subnet
resource "google_compute_subnetwork" "subnet" {
  name          = "${var.project_id}-subnet"
  region        = var.region
  network       = google_compute_network.vpc.name
  ip_cidr_range = "10.10.0.0/24"
}

# GKE cluster
resource "google_container_cluster" "primary" {
  name     = "${var.project_id}-gke"
  location = var.region

  remove_default_node_pool = true
  initial_node_count       = 1

  network    = google_compute_network.vpc.name
  subnetwork = google_compute_subnetwork.subnet.name

  # Create a VPC-native cluster by configuring `ip_allocation_policy` 
  ip_allocation_policy {
    cluster_ipv4_cidr_block  = "/16"
    services_ipv4_cidr_block = "/22"
  }

  master_auth {
    username = var.gke_username
    password = var.gke_password

    client_certificate_config {
      issue_client_certificate = false
    }
  }
}

# Separately Managed Node Pool
resource "google_container_node_pool" "primary_nodes" {
  name       = "${google_container_cluster.primary.name}-node-pool"
  location   = var.region
  cluster    = google_container_cluster.primary.name
  node_count = var.gke_num_nodes

  node_config {
    oauth_scopes = [
      "https://www.googleapis.com/auth/logging.write",
      "https://www.googleapis.com/auth/monitoring",
    ]

    labels = {
      env = var.project_id
    }

    # preemptible  = true
    machine_type = "n1-standard-1"
    tags         = ["gke-node", "${var.project_id}-gke"]
    metadata = {
      disable-legacy-endpoints = "true"
    }
  }
}

Here is my terraform script file for creating the Postgres server:

variable "project_id" {
  description = "project id"
}

variable "region" {
  description = "region"
}

terraform {
  required_providers {
    google = {
      source = "hashicorp/google"
      version = "3.61.0"
    }
  }
}

data "google_compute_network" "my_network" {
  name = "novade-lite-vpc"
}

provider "google" {
  project = var.project_id
  region  = var.region
}

resource "random_id" "db_name_suffix" {
  byte_length = 4
}

resource "google_compute_global_address" "private_ip_address" {
  name          = "private-ip-address"
  purpose       = "VPC_PEERING"
  address_type  = "INTERNAL"
  prefix_length = 16
  network       = data.google_compute_network.my_network.self_link
}

resource "google_service_networking_connection" "private_vpc_connection" {
  network                 = data.google_compute_network.my_network.self_link
  service                 = "servicenetworking.googleapis.com"
  reserved_peering_ranges = [google_compute_global_address.private_ip_address.name]
}

resource "google_sql_database_instance" "postgres" {
  name             = "postgres-instance-${random_id.db_name_suffix.hex}"
  database_version = "POSTGRES_11"
  depends_on = [google_service_networking_connection.private_vpc_connection]

  settings {
    tier = "db-f1-micro"

    ip_configuration {
      ipv4_enabled    = false
      private_network = data.google_compute_network.my_network.self_link
    }
  }
}

resource "google_sql_database" "default" {
  name       = "default"
  project    = var.project_id
  instance   = google_sql_database_instance.postgres.name
  collation  = "en_US.UTF8"
  depends_on = [google_sql_database_instance.postgres]
}

resource "google_sql_user" "users" {
  name     = "postgresadmin"
  instance = google_sql_database_instance.postgres.name
  password = "password"
  depends_on = [google_sql_database_instance.postgres]
}

Here is my variables file (Same for both the above scripts):

project_id = "test-project"
region     = "europe-west2"

Any help is much appreciated! 🙏