Resolved : Apcu with PECL failing

Hello,

I ran into a strange problem. Twenty minutes ago, a job was working fine. Now it is failing installing apcu from pecl.

pecl install apcu && docker-php-ext-enable apcu
No releases available for package "pecl.php.net/apcu"

Going to the pecl.php.net, my browser is indicating a problem of expired SSL certificate.
But it feels strange to me as it passed the installation of zip from pecl.

pecl channel-update pecl.php.net && docker-php-ext-enable xdebug
pecl install zip && docker-php-ext-enable zip

I am using the 7.2-apache-node-browsers-legacy CircleCI docker image.
Do have an idea why the same instruction failed twenty minutes later? (I rebuilt the job with the same output.)
I am using CircleCi for quite some time but I am not a docker expert. I use Vagrant locally.

Thank you

Edit : the problem has been fixed twice. (one compiling manually the source of apcu)
The problem was due to the expired SSL certificat and HSTS of the subdomain.

Hi Julien. Thanks for sharing the answer!