Azure PostgreSQL Flexible in Aspire on Local PC

In this exercise, I focused on only one Azure resource: Azure PostgreSQL Flexible Server. My goal was simple: run PostgreSQL locally,
connect a console client project to it through .NET Aspire, and validate that the client can open a database connection end-to-end.

How it looks like

This is the PostgreSQL container / database view

How I wired Azure PostgreSQL in Aspire AppHost

In AzureEmulators/AppHost.cs, I added Azure PostgreSQL Flexible Server as a container and then defined one database.
Then I connected the PostgreSQL client project to that database with WithReference(postgresdb) and WaitFor(postgresdb).

PostgreSQL Flexible Server resource: postgres1
Database: postgresdb1
Client project reference: postgresClient1

var postgres = builder.AddAzurePostgresFlexibleServer("postgres1")
        .RunAsContainer()
        ;

var postgresdb = postgres.AddDatabase("postgresdb1");

var postgresProj = builder
    .AddProject<Projects.PostgresClient>("postgresClient1")
    .WithReference(postgresdb)
    .WaitFor(postgresdb)
    ;

What my PostgresClient project does

In PostgresClient/Program.cs, I implemented a simple startup flow to validate PostgreSQL connectivity.

I scan environment variables and pick the PostgreSQL connection string.
I fail fast if the connection string is missing.
I create an NpgsqlConnection using that connection string (Npgsql is the .NET driver for PostgreSQL).
I call OpenAsync() to confirm I can connect to the database.

Code from my console client project

using Npgsql;
using System.Collections;

Console.WriteLine("Hello, Postgres!");

string connectionStringPostgres = "";
foreach (var item in Environment.GetEnvironmentVariables().Cast<DictionaryEntry>())
{
    if (item.Key?.ToString()?.Contains("postgres") == true)
    {
        //Console.WriteLine($"{item.Key}: {item.Value}");
        connectionStringPostgres = item.Value?.ToString() ?? string.Empty;
    }
}
if (string.IsNullOrWhiteSpace(connectionStringPostgres))
{
    Console.WriteLine("Postgres  connection string is not set in environment variables.");
    return;
}
Console.WriteLine($"Connection string for Postgres: {connectionStringPostgres}");
await using var conn = new NpgsqlConnection(connectionStringPostgres);
await conn.OpenAsync();
Console.WriteLine($"Success opening the database");

Output logs from my client project

Waiting for resource 'postgres1' to enter the 'Running' state.
Waiting for resource 'postgresdb1' to enter the 'Running' state.
Waiting for resource 'postgresdb1' to become healthy.
Waiting for resource 'postgres1' to become healthy.
Waiting for resource ready to execute for 'postgres1'.
Finished waiting for resource 'postgres1'.
Waiting for resource ready to execute for 'postgresdb1'.
Finished waiting for resource 'postgresdb1'.
Hello, Postgres!
Connection string for Postgres: Host=localhost;Port=51116;Username=postgres;Password=K1K*zHE4mrKSX{{rgg2tNT;Database=postgresdb1
Success opening the database

What is achieved

I can run Azure PostgreSQL Flexible Server on my local PC without provisioning a cloud PostgreSQL resource.
I get dependency wiring from Aspire between AppHost and PostgresClient.
I proved connectivity by opening the PostgreSQL connection successfully from the client project using Npgsql.