Rob Allen has a post to his site for the OpenWhisk (a serverless cloud platform) users out there that want to use Composer to install dependencies required by your application.
When creating new OpenWhisk actions in PHP, It's likely that you'll want to take advantage of the rich ecosystem of Composer packages on Packagist.org.
The OpenWhisk PHP runtime has you covered with some pre-installed Composer packages and also the ability to upload your own using a zip file.
He starts by mentioning the two packages that come installed by default: Guzzle and the ramsey/uuid library. He then gets into the upload of your own project files as a ZIP file and how to install the package locally, bundle it up into this archive and push it using the
wsk command line tool.