Php Storage not defining secret index.

We also have this message on all Acquia Cloud hostings. We reported that, but they could not find the error.

That is a clear sign of the sadness of Acquia Cloud to not write the hash salt into settings.php on install, see core/lib/Drupal/Core/PhpStorage/PhpStorageFactory.php:47

Afaik they don't allow settings.php to be writeable at all, so you better do it on your own :)

I might be misunderstanding, but we setup our site outside of Acquia, and have a hash_salt defined, and are getting the same error only on our Acquia environment. I've also tried defining the hash_salt again after including the Acquia stuff, but still the same issue. I do think it's an Acquia thing, but am not entirely clear what I'm missing.

I have tested this issue but I am not able to replicate this on the vanilla install of Drupal running on 8.0.x branch. This might be Acquia environment related issue hence, can be closed.

I came across this issue only after I modified my $settings['php_storage'] array in the settings.php. I resolved it by adding the following at the end of the settings.php file:

$settings['php_storage']['twig']['secret'] = $settings['hash_salt'];

I feel like manually setting the Twig secret in settings.php is only treating the symptom.

I think there are three solutions, but I don't know the Core well enough to know about any side effects.

1. Modify \Drupal\Component\PhpStorage\MTimeProtectedFastFileStorage such that the constructor either ignores or prepends the hash_salt when it pulls the secret from the $configuration variable. (e.g., $this->secret = $configuration['secret']; should be $this->secret = isset($configuration['secret']) ? : Settings::getHashSalt() -or- '';)

2. Modify \Drupal\Core\PhpStorage\PhpStorageFactory to automatically add the hash_salt to the $configuration array if one is not set. Perhaps log this as an error if it's not set.

3. Modify \Drupal\Core\Template\TwigPhpStorageCache (or wherever else Twig's Storage Cache sets its configuration) to include the provided hash_salt.

Comments #8 and #9 seem basically correct to me.

We already have a check for:
isset($configuration['class'])

This patch just merges in the 2 required keys instead of having an else clause.

mm, how about this. Doesn't break the test, and adds a little more coverage (and converts 2 deprecated method calls).

I also encountered this problem recently on a site hosted on Acquia Cloud, and the patch makes sense :)

Just one nit though:

+++ b/core/modules/system/tests/src/Kernel/PhpStorage/PhpStorageFactoryTest.php
@@ -65,18 +65,28 @@ public function testGetOverride() {
+    $this->assertNotEquals('mock hash salt', $php->getConfigurationValue('secret'), 'The default secret is used if one is not set in the overridden settings.');

This message is copied from below, so it's not really accurate for this assertion.

Thanks - here's the patch with a fix for the test text.

Committed ed78a4c and pushed to 8.0.x, 8.1.x and 8.2.x. Thanks!