Composer in a hosting environment.
WHERE TO RUN IT
Through terminal access in cPanel, where available.
WHAT TO RUN
Installation from the lock file, excluding development dependencies, with the class loader optimised.
WHY EXCLUDE DEVELOPMENT DEPENDENCIES
They are unnecessary in production and enlarge the footprint.
WHAT TO SPECIFY
The correct PHP version, since the default in the terminal may differ from the one serving your site.
THAT POINT
A common cause of installation succeeding and the site still failing.
WHAT CAN FAIL
Memory limits during installation Extensions missing Process limits
WHAT TO DO ABOUT MEMORY
Run with an increased limit, where permitted.
WHAT TO DO IF INSTALLATION IS NOT POSSIBLE
Install locally and upload the dependencies directory.
WHAT TO VERIFY
That the installed versions match your lock file.
WHAT NOT TO DO
Run an update in production, which changes versions unpredictably.
WHAT TO RUN INSTEAD
Installation, which honours the lock file exactly.
WHAT TO CHECK AFTERWARDS
That the application loads.
