Here's an update

This was the answer "Use a unix socket to connect in your go program. Using host := "/var/run/postgresql/" should work"

Here is the script I ended up using which worked:

package main

import (
    "database/sql"
    "fmt"
    "log"

    _ "github.com/lib/pq"
)

func main() {
    // Define the connection parameters
    // Replace "<dbname>" and "<username>" with your PostgreSQL database and user.
    socketDir := "/var/run/postgresql"
    database := "eos_db"
    user := "eos_user"

    // Connection string
    connStr := fmt.Sprintf("host=%s dbname=%s user=%s sslmode=disable", socketDir, database, user)

    // Open a connection
    db, err := sql.Open("postgres", connStr)
    if err != nil {
        log.Fatalf("Failed to open a connection: %v", err)
    }
    defer db.Close()

    // Test the connection
    err = db.Ping()
    if err != nil {
        log.Fatalf("Failed to connect to the database: %v", err)
    }

    fmt.Println("Successfully connected to PostgreSQL over UNIX socket!")

    // Example query
    query := "SELECT current_date"
    var currentDate string
    err = db.QueryRow(query).Scan(&currentDate)
    if err != nil {
        log.Fatalf("Query failed: %v", err)
    }

    fmt.Printf("Current date from PostgreSQL: %s\n", currentDate)
}

And here is the terminal output

henry@vhost1:~/Eos$ sudo -u eos_user go run postgresUnixSockTest.go
Successfully connected to PostgreSQL over UNIX socket!
Current date from PostgreSQL: 2024-12-24T00:00:00Z
henry@vhost1:~/Eos$

Cheers