# Streamline Local Development on macOS: Custom Domain Names for Docker and Services

Setting up a local domain name on OSX can streamline your development process by allowing you to access your Docker containers or other services via a custom, easy-to-remember URL. This is particularly useful for multisite applications, as it lets you choose a custom domain for every site for local development. It's also possible to add several custom domain names for 127.0.0.1.

### Step 1: Open Your Terminal

Launch the Terminal application from your Applications folder or use Spotlight Search.

### Step 2: Edit the Hosts File

1. **Open the Hosts File**: Use the following command to open the hosts file in a text editor. This file maps domain names to IP addresses.
    
    ```bash
    sudo vim /etc/hosts
    ```
    
    The `sudo` command is necessary because the hosts file is a system file, and editing it requires administrative privileges. You'll be prompted to enter your password.
    
2. **Add Your Custom Domain**: Add new lines in the hosts file with the desired local domain names and the IP address of your service. For instance, to map `myapp.local` and `mysite.local` to `127.0.0.1`:
    
    ```plaintext
    127.0.0.1 myapp.local
    127.0.0.1 mysite.local
    ```
    
    In vim, press `i` to enter insert mode, add the lines, then press `Esc` to exit insert mode. Type `:wq` and press `Enter` to save and exit.
    
    Adding these entries tells your computer to resolve `myapp.local` and `mysite.local` to `127.0.0.1`, which is the loopback address pointing to your local machine. This is useful for accessing locally hosted services or Docker containers via a custom URL.
    

### Step 3: Save and Exit

1. **Save Changes**: In vim, after adding your custom domain entries, press `Esc` to exit insert mode. Then type `:wq` and press `Enter` to save and close the file.
    
2. **Flush DNS Cache**: Ensure your changes take effect by flushing the DNS cache. This clears any cached DNS records and forces the system to read the updated hosts file.
    
    ```bash
    sudo dscacheutil -flushcache
    ```
    
    Flushing the DNS cache is crucial to ensure that your changes to the hosts file are recognized by your system immediately.
    

### Step 4: Configure Docker Container (if using Docker)

1. **Run Your Docker Container**: Make sure your Docker container is running. For example, to run an NGINX server, use the following command:
    
    ```bash
    docker run -it --rm -d -p 80:80 --name my-nginx nginx
    ```
    
    This command starts an NGINX container, mapping port 80 of the container to port 80 of your local machine. The `--rm` flag ensures the container is removed after it stops, and `-d` runs the container in detached mode.
    
2. **Access via Custom Domain**: You should now be able to access your Docker container using the custom domain names, e.g., [`http://myapp.local`](http://myapp.local) and [`http://mysite.local`](http://mysite.local). Open a web browser and navigate to these URLs to verify that your container is accessible via the custom domains.
    

Happy coding!