websites/Gitlab-Issue-Listing-Script#56: Whitescreen on project page caused by empty Container List

Turns out this isn't Redis related - have updated the description.

I'm not sure how we got here yet, but the issue is here

$c = $this->getContainers($proj_path);
$o['has_containers'] = (count($c['containers']) > 0)? true : false;

That function, at first glance, looks reasonable safe:

    function getContainers($proj_path){
        global $config;

        if (!$this->enforceProjectFilters($proj_path)){
            http_response_code(404);
            echo "Containers Not found";
            die;
        }        

        $url = $config->server . "/api/v4/projects/" . urlencode($proj_path) . "/registry/repositories/?tags=true";
        $r = $this->callAPI("GET", $url, false, $config->do_auth);

        $containers = json_decode($r['result']);    

        if (is_object($containers) && $containers->message){
            $containers = array();
        }

        $o = array(
            "containers" => $containers,
            "project" => $this->getProject($proj_path)
        );

        return $o;           
    }

But.... what if the returned result is not an object? If we get an empty response back (for whatever reason) then we won't add the empty array.

Dropping a print_r() in there confirms it

Array ( [result] => [headers] => Array ( ) [links] => Array ( ) ) 

The request failed (potentially because of the Redis issue, but we'll deal with that seperately).

The commit handles this particular failure case.

Now need to look into the Redis handling - the page is no longer generating a 500, but we're also not getting any data back. Presumably the Redis container has OOM'd or similar.

I'll raise a separate issue to track improving handling of that

FTR looks like we already handle Redis issues sanely

            try {
                $this->redis->connect($config->redis_host, $config->redis_port);

                if ($config->redis_pass){
                    $this->redis->auth($config->redis_pass);   
                }
            }
            catch (exception $e){
                // We failed to connect
                // let's not kill the application
                // The library will push warnings out, so it's not a silent failure
                $this->redis = false;
            }

Presumably, whatever interrupted name resolution also prevented us resolving the name of Gitlab's API, which is why pages came back without content.