How to fix "https://repo.packagist.org/packages.json does not contain valid Json"?

I've an issue with composer running on a vagrantbox (Centos 7), which started to just suddenly happen.

I've already tried manually running the command/solution mentioned on the link below but to no avail.

(To clarify, i'm using vagrant not docker, but it was the closest question i found to my situation. Most of the information i found are related to composer.json not being valid, but here is packagist.org/packages.json which, is currently valid)

Composer not working in docker container: "https://packagist.org/packages.json" does not contain valid JSON

Here are the details of the issue.

While running composer update on terminal i get:

 composer update  [Seld\JsonLint\ParsingException]"https://repo.packagist.org/packages.json" does not contain valid JSON  Parse error on line 1:  ^  Expected one of: 'STRING', 'NUMBER', 'NULL', 'TRUE', 'FALSE', '{', '['

And when running composer install also on terminal every package returns this:

Failed to download psr/cache from dist: "https://api.github.com/repos/php-fig/cache/zipball/d11b50ad223250cf17b86e38383413f5a6764bf8"appears broken, and returned an empty 200 response    Now trying to download from source

When running composer config --global repo.packagist composer packagist.orgthe results are now

composer updateLoading composer repositories with package information  [Composer\Downloader\TransportException]  Your configuration does not allow connections to http://repo.packagist.org/packages.json. See https://getcomposer.o  rg/doc/06-config.md#secure-http for details.

Any ideas why this started to happen, how can i fix it?