FOS\HttpCache\Exception\ProxyUnreachableException: Request to caching proxy at ecamp3-prod-api-cache:3001 failed with message "Could not resolve host: ecamp3-prod-api-cache for "http://ecamp3-prod-api-cache:3001/"."

[sentry-io]

Sentry Issue: ECAMP3-API-6K

TODO: test if we return a 500er status code if the cache is not reachable.
maybe find out, why the cache could not be reachable?
Symfony\Component\HttpClient\Exception\TransportException: Could not resolve host: ecamp3-prod-api-cache for "http://ecamp3-prod-api-cache:3001/".
  File "/src/HttpCache/VarnishProxyClient.php", line 73, in App\HttpCache\VarnishProxyClient::flush
    return parent::flush();
  File "/src/HttpCache/PurgeHttpCacheListener.php", line 120, in App\HttpCache\PurgeHttpCacheListener::postFlush
    $this->cacheManager->flush();
  File "/src/State/Util/AbstractPersistProcessor.php", line 47, in App\State\Util\AbstractPersistProcessor::process
    $data = $this->decorated->process($data, $operation, $uriVariables, $context);
  File "/public/index.php", line 5
    require_once dirname(__DIR__).'/vendor/autoload_runtime.php';
...
(31 additional frame(s) were not displayed)

Symfony\Component\HttpClient\Exception\TransportException: Could not resolve host: ecamp3-prod-api-cache for "http://ecamp3-prod-api-cache:3001/".
  File "/src/HttpCache/VarnishProxyClient.php", line 73, in App\HttpCache\VarnishProxyClient::flush
    return parent::flush();
  File "/src/HttpCache/PurgeHttpCacheListener.php", line 120, in App\HttpCache\PurgeHttpCacheListener::postFlush
    $this->cacheManager->flush();
  File "/src/State/Util/AbstractPersistProcessor.php", line 47, in App\State\Util\AbstractPersistProcessor::process
    $data = $this->decorated->process($data, $operation, $uriVariables, $context);
  File "/public/index.php", line 5
    require_once dirname(__DIR__).'/vendor/autoload_runtime.php';
...
(28 additional frame(s) were not displayed)

Http\Client\Exception\NetworkException: Could not resolve host: ecamp3-prod-api-cache for "http://ecamp3-prod-api-cache:3001/".
  File "/src/HttpCache/VarnishProxyClient.php", line 73, in App\HttpCache\VarnishProxyClient::flush
    return parent::flush();
  File "/src/HttpCache/PurgeHttpCacheListener.php", line 120, in App\HttpCache\PurgeHttpCacheListener::postFlush
    $this->cacheManager->flush();
  File "/src/State/Util/AbstractPersistProcessor.php", line 47, in App\State\Util\AbstractPersistProcessor::process
    $data = $this->decorated->process($data, $operation, $uriVariables, $context);
  File "/public/index.php", line 5
    require_once dirname(__DIR__).'/vendor/autoload_runtime.php';
...
(27 additional frame(s) were not displayed)

FOS\HttpCache\Exception\ProxyUnreachableException: Request to caching proxy at ecamp3-prod-api-cache:3001 failed with message "Could not resolve host: ecamp3-prod-api-cache for "http://ecamp3-prod-api-cache:3001/"."
  File "/src/HttpCache/VarnishProxyClient.php", line 73, in App\HttpCache\VarnishProxyClient::flush
    return parent::flush();
  File "/src/HttpCache/PurgeHttpCacheListener.php", line 120, in App\HttpCache\PurgeHttpCacheListener::postFlush
    $this->cacheManager->flush();
  File "/src/State/Util/AbstractPersistProcessor.php", line 47, in App\State\Util\AbstractPersistProcessor::process
    $data = $this->decorated->process($data, $operation, $uriVariables, $context);
  File "/public/index.php", line 5
    require_once dirname(__DIR__).'/vendor/autoload_runtime.php';
...
(20 additional frame(s) were not displayed)

Request to caching proxy at ecamp3-prod-api-cache:3001 failed with message "Could not resolve host: ecamp3-prod-api-cache for "http://ecamp3-prod-api-cache:3001/"."