Ok, this is info I should have documented here a long, long time ago. For many months now this tidbit of wisdom has lived on a post-it in my office. Not the best strategy for someone who works from home and travels a lot.

Apparently OSX ships with built-in Apache and/or NGINX servers, presumably to facilitate creation of web content that’s local to the machine. Well, in my Dockerized workflows those port assignments typically get in the way. When they do, like when I do a fin up to launch a local development project using Docksal, I see error messages like the following in my terminal:

docker: Error response from daemon: driver failed programming external connectivity on endpoint docksal-vhost-proxy (4b78f8d326c8461a2c6896f0def4491c9d115feeee3680da1f3a5285a707aa08): Error starting userland proxy: Bind for failed: port is already allocated.  

Errors like this simply indicate that something, a process or service (container), is already listening on the indicated port. Frequently that ‘something’ is the aforementioned built-in ‘Apache’ or ‘NGINX’ web server on my Mac.

Disabling OSX Built-In Web Servers

There is a simple fix… in my Mac terminal I simply need to enter:

sudo apachectl stop
sudo nginx -s stop

Changing Docksal Proxy Port Assignments

Docksal itself can also get in the way because by default its proxy service listens locally on ports 80 and 443. In cases like my omeka-s-docker project, I needed my Omeka service listening on port 80.

Fortunately, there is another simple fix, and it’s nicely documented in this post. In my Omeka case I simply added the following lines to the .docksal/docksal.env file in the project directory:


These variable settings instruct the Docksal proxy to listen on ports 8080 and 8443, making ports 80 and 443 available for my Omeka service.

And that’s a wrap. Until next time…