During implementation of T166355: Detect when CirrusSearch is used without curl and fail gracefully our GCI student found, that at least CI host integration-slave-docker-1005 obviously lacks he curl php extension, as mwext-php70-phan-docker fails with this message currently (once ext-curl was added to the list of required extensions in composer.json) during the composer validate step:
19:19:54 [7.0MB/0.08s] > ComposerHookHandler::onPreUpdate 19:19:54 [7.0MB/0.08s] Loading composer repositories with package information 19:19:54 [7.4MB/0.21s] Updating dependencies 19:19:58 [232.9MB/3.62s] Your requirements could not be resolved to an installable set of packages. 19:19:58 [232.9MB/3.62s] 19:19:58 Problem 1 19:19:58 - The requested PHP extension ext-curl * is missing from your system. Install or enable PHP's curl extension. 19:19:58 19:19:58 [152.0MB/3.69s] Memory usage: 152.04MB (peak: 232.96MB), time: 3.69s
(Source: https://integration.wikimedia.org/ci/job/mwext-php70-phan-docker/1795/console)
The integration-* hosts should either include the curl extension or the composer-validate step should be part of the docker script in this case (which will not work for other jobs, that probably run composer validate, too).