Table of Contents
Varnish is a very fast reverse-proxy system which serves static files and anonymous page views based on the previously processed requests. The Nexteuropa Varnish module provides functionality which allows to send customized HTTP request to the Varnish server based on the configured 'purge rules' in the form of regular expressions. The main purpose of those requests is to invalidate the Varnish cache to display recently published content changes.
This feature can be enabled only with the support of the QA/Maintenance team.
The following environment specific variables have to be configured before enabling the feature:
'nexteuropa_varnish_request_user' - a string with the username
'nexteuropa_varnish_request_password' - a string with the password
'nexteuropa_varnish_http_targets', - an array with the urls ex. 'http://localhost'
'nexteuropa_varnish_tag', - a string with the tag
'nexteuropa_varnish_request_method' - a string with the HTTP request method
'nexteuropa_varnish_http_timeout' - a float representing the maximum number
of seconds the function call may take (by default 2.0)
In order to enable the feature make sure that above variables are set
and if so then go to the admin/structure/feature-set page,
select the 'Rule-based web frontend cache purging' feature
and click on the 'Validate' button.
Nexteuropa Varnish provides a 'Administer frontend cache purge rules' permission which allows to create and maintain 'purge rules'.
Configuration page is located here admin/config/system/nexteuropa-varnish.
The configuration page provides a "Purge all caches" button.
Once it is clicked, this button will trigger:
- The cleaning of the "Drupal cache" if Clear drupal cache as well is also ticked;
- The purging of ALL site's entries indexed in the Varnish cache.
Checking "Drupal cache" has impact on the site's performance as it forces Drupal to rebuild all requested pages, use cautiously.
See description in UI.
The module provides an custom entity type allowing to define purge rules:
Purge rule - machine name: 'nexteuropa_varnish_cache_purge_rule'
Click the 'Add cache purge rule' link. You will be redirected to the 'Add cache purge rule' form.
The Content type select box allows to limit triggering a rule to one type of node.
For example, you want to trigger the clearing of my-news only when content of type news is added,
edited or removed.
Selecting 'All' will apply to all node types.
If the default purge rule is disabled, the option Paths of the node the action is performed on will appear.
Just save it. The behaviour is similar to the default, except you can restrict to content types.
The option A specific list of regex allows defining a set of regex matching the paths you want to clear.
The field description provides hints for testing validity of the regex you entered in the field.
After setting up a rule you need to submit it by clicking the 'Save' button. If the regular expression you entered is not valid, the following warning will be shown
Regex is invalid.
Please check your expression at the Regex101 page.
After the creation of a new rule you will be redirected to the page with the list of rules. From that page you can use option to add a new rule or edit, delete existing rules.
The Nexteuropa Varnish provides hardcoded logic for triggering configured rules. Current version implements two workflow cases for:
- content types moderated via the workbench moderation module
- content types without additional moderation (default Drupal settings)
For the content types which are controlled via the workbench moderation module, created purge rules will be triggered in the following cases:
- when a given content has a workflow state change to 'Published'
- when a given content has a workflow state change from 'Published' to any other
For the content types which are not moderated (default Drupal content type with two states: published and unpublished), created purge rules will be triggered in the following cases:
- when a node of the given content type is created and saved with the 'Publish' state
- when a published node of the given content type is updated
To set up workflows, more intricate scenarios, for flushing varnish paths a rules action 'Varnish flush' was added under the 'Nexteuropa Varnish' group.
This way you can add one or more path aliases in regexp format, even use available tokens and create your own flushing rules in admin/config/workflow/rules.
The Nexteuropa Varnish provides complete a Behat test suite and additional Feature Context located in the FrontendCacheContext class.
Tests are performed against a mocked HTTP server. The only difference is that the mocked HTTP server doesn't support 'PURGE' method and uses the 'POST' method instead.
You can find the Behat scenarios in the frontend_cache_purge.feature file located under the test folder.
Nexteuropa Varnish uses the https://www.drupal.org/project/chr module
which overrides the default drupal_http_request() function.
A custom patch was created for this specific feature The patch can be found here
The patch adds the 'PURGE' HTTP method, which is commonly used by systems such as Varnish, Squid and SAAS CDNs like Fastly to clear cached versions of certain paths.
All of HTTP requests are send by the _nexteuropa_varnish_purge_paths()
function.
To support rules integration for file entities we added another path.
Next Europa Varnish feature provides a feature to prevent from sending all supported purge requests.
To do so, the following line must be added to the settings file:
$conf['nexteuropa_varnish_prevent_purge'] = TRUE;
Once it is added, no purge request will be sent to Varnish and the "Purge all caches" button will be disabled.
Nevertheless, it is still possible to manage the purge rules during the blocking period.
In order to test varnish on C9 environement, please perform these steps:
- Make sure your environement is up to date. See FAQs on confluence for more information or type :
sudo salt-call state.apply tools.varnish-mock
- Add this to your settings.php file
$conf['nexteuropa_varnish_request_method'] = "PURGE";
$conf['nexteuropa_varnish_http_targets'] = array ("http://127.0.0.1:6081");
$conf['nexteuropa_varnish_tag'] = "drupal-760";
$conf['nexteuropa_varnish_request_user'] = "user";
$conf['nexteuropa_varnish_request_password'] = "password";
$conf['nexteuropa_varnish_http_timeout'] = "30";
-
Launch the mock
varnish-mock -
By default, the mock prints information on console. Output file can be used with the "-filePath" parameter: Type
varnish-mock -hto get help
Please note that the value of the base_path variable on your site has an impact on the path of the node sent.
Because previous versions of the module did not support fully regular expressions , the validation of the rules exceptions have been added upon saving a new rule and upon triggering a rule. Therefore, if you entered a rule in a previous version and this rule does not match the more strict criterias now in place, a warning will appear :
Please check your varnish rules , the regex ^an-already-inserted/rule you are trying to flush is not valid.
We suggest you review and save your regex rules again using the documentation available.
In case of doubt, please contact your site administrator or the devops team.
v1.0.8 : NEPT-1961: Provide 'rules' action to allow purging any entity. v1.0.7 : Block unwanted purges and prevent watchdog flooding. v1.0.6 : Clear file path and solve diverged declaration. v1.0.5 : Remove "check scope" button. v1.0.4 : Update documentation link reference to new repository. v1.0.3 : Implement file flushing. v1.0.2 : Migrate module from platform to standalone repository.