Connecting Docker to PostgreSQL Outside Docker

When Docker containers are isolated from the host system, connecting to a PostgreSQL server running on WSL (Windows Subsystem for Linux) requires specific configurations.

Methods to Connect Docker to PostgreSQL:

Host Networking:
```
docker run --network="host" -p 8181:8181 docker-todo-app
```
This allows the Docker container to use the host’s network and access PostgreSQL on 127.0.0.1.

Using Docker Compose: Create a docker-compose.yml:

version: '3.8'

services:
  app:
    build:
      context: .
      dockerfile: Dockerfile
    ports:
      - "8181:8181"
    depends_on:
      - db
    environment:
      DB_HOST: db
      DB_PORT: 5432
      DB_DATABASE: your_database
      DB_USERNAME: your_username
      DB_PASSWORD: your_password

  db:
    image: postgres:latest
    environment:
      POSTGRES_DB: your_database
      POSTGRES_USER: your_username
      POSTGRES_PASSWORD: your_password
    ports:
      - "5432:5432"

In your .env file:

DB_CONNECTION=pgsql
DB_HOST=db
DB_PORT=5432
DB_DATABASE=your_database
DB_USERNAME=your_username
DB_PASSWORD=your_password

Run with:

docker-compose up

Exposing WSL IP Address: Find the WSL IP address:
```
ip addr show eth0
```
Update your .env file:
```
DB_CONNECTION=pgsql
DB_HOST=your_wsl_ip_address
DB_PORT=5432
DB_DATABASE=your_database
DB_USERNAME=your_username
DB_PASSWORD=your_password
```
Ensure PostgreSQL is configured to accept external connections by modifying postgresql.conf and pg_hba.conf.

Using these methods should resolve connection issues between your Docker container and the PostgreSQL server on WSL.