Pantheon uses its Object Cache and Global CDN services to help improve the performance of your Drupal sites. Using them requires a few steps to enable the services and configure your Drupal site to use them effectively.

Many performance optimizations are hosting-provider-specific. This tutorial covers some Pantheon-specific methods for increasing your Drupal site's performance. It's only relevant if your site is hosted on Pantheon. For other common providers, and generic performance tuning tips, refer to other tutorials in this course.

In this tutorial we'll:

• Learn how to configure and use Pantheon's Object Cache to speed up Drupal caching
• Learn about the use case for Pantheon's Advanced Page Cache module
• Install and configure the Advanced Page Cache module for better Drupal caching of sites hosted on Pantheon

By the end of this tutorial you should be able to explain when and why you would want to use Pantheon's Object Cache and Advanced Page Cache modules, and how they can help speed up Drupal sites hosted on Pantheon.

Over the history of the Internet, the single Page Speed metric evolved into various parameters that influence user experience. These metrics are commonly referred to as Core Web Vitals. Together, they paint a comprehensive picture of the performance of your site from an end user's perspective. These metrics are considered by Google and other search engines when assigning SEO scores.

Knowing what these metrics are, and what they are intended to measure, is an important part of creating a performance profile for your site. This knowledge can also help you find solutions for common performance issues.

In this tutorial, we'll:

• Define the metrics that make up the Core Web Vitals
• Point to additional resources where you can learn more about each metric

By the end of this tutorial, you should know which performance metrics are considered Core Web Vitals and what aspects of site performance they cover.

The performance optimization settings and modules provided by Drupal core are intended to work for the broadest possible set of use cases. From an administrator's perspective they provide minimal configuration options, and are designed to just work by being enabled. But behind that simplicity are some powerful features that will help speed up any Drupal-powered application.

The core Dynamic Page Cache and Internal Page Cache modules are designed to provide a base cache setup for any site. These modules are responsible for the static page cache, dynamic page cache, and lazy loading optimizations.

For developers, Drupal provides a complete and well-designed Cache API. You can, and should, integrate it into your custom code. This integration includes defining the cacheability of any content your module outputs so that Drupal can be smart about how that affects how and when a page that incorporates the output can be cached -- as well as storing and retrieving the results of complex or long-running operations. The API also helps with setting appropriate HTTP headers for the responses Drupal generates for each request so that the user's browser and other layers in the stack can appropriately cache the output.

The entire system is flexible, and there are many contributed modules that can aid in making the default caching system even faster for specific use cases.

In this tutorial, we'll:

• Learn about the caching-related modules in Drupal core
• Review the Drupal core performance settings and recommended values

By the end of this tutorial you should be familiar with the Drupal core modules responsible for caching, their settings, and recommended values.

There's no magical set of right tools to use to monitor a Drupal site's performance and health. While thinking about performance monitoring, you need to optimize your approach depending on the number of applications you manage, their complexity, business needs, and the skill-set of your team. Based on these factors, you may choose to use one of the core or contributed modules, go with third-party solutions and services, or some combination of both.

Drupal core comes with a couple of modules that allow you to monitor the health and performance of the site including Syslog, Database Logging, and the status reports provided by the System module. There are also numerous community-contributed modules, a sampling of which we'll cover here.

In this tutorial, we'll:

• List some contributed modules that are commonly used for monitoring a Drupal site
• Provide an overview of what each module does

By the end of this tutorial you should be able to list a few contributed modules that might be useful for monitoring your Drupal application and define what each one does.

New Relic is a monitoring service that provides insights into your application stack from front-end performance to the server and infrastructure metrics. New Relic uses a combination of aggregating server logs, and pre-built (or custom) monitors to track the metrics that are most important to your application. The collected data can be organized into custom dashboards, and alerts can be set up and issued per customizable conditions.

In this tutorial, we'll:

• Learn about different New Relic modules and their purpose
• Review some default dashboard components and reports
• Discuss how to use the information in New Relic to understand the health of your Drupal application

By the end of this tutorial, you should understand the basics of using New Relic and the insights it offers to monitor and improve the performance of your Drupal site.

Performance profiling allows you to see an overview of how your Drupal application stacks up against your users' needs and business requirements. A good profile will help you understand where the performance bottlenecks are and where you should focus your efforts in order to achieve the best results when optimizing your application.

There are many profiling tools available to help you analyze your Drupal site's performance. Some are free -- like the browser’s built-in development tools, the Lighthouse Chrome extension, and XHProf. Some are paid -- like New Relic, Blackfire, and other profiling SaaS solutions.

In this tutorial we'll:

• Outline the general concepts and goals of performance profiling
• List some available profiling tools and their features

By the end of this tutorial you should be able to describe what performance profiling is, and list the tools commonly used to establish a performance profile for a Drupal site.

When your site is experiencing performance issues, one way to pinpoint the cause is to use profiling tools. Before you can fix the issue you have to be able to identify what's causing it. All profiling tools do roughly the same thing: they tell you what code is called during the request and how much time is spent executing it. This helps to identify the slowest code and dig deeper into the cause. Once the cause is determined you can start figuring out how to optimize the code.

For this tutorial, we’ll use New Relic as a profiling tool, but you can apply a similar methodology using the profiling tool of your choice.

In this tutorial, we'll:

• Learn how to identify and analyze slow transactions
• Look at common things to check for while profiling
• Cover some questions you should ask when looking at profiling data to help track down the slow code

By the end of this tutorial, you should know how to profile a Drupal site (specifically with New Relic) to find performance bottlenecks.

Drupal site performance relies heavily on caching. Optimal caching (and invalidation) requires that each page is rendered with the correct cacheable metadata. This metadata allows for intelligent caching -- but when something isn't working correctly, it can be tricky to figure out where exactly the metadata was generated from.

When debugging Drupal cache issues, you're usually trying to answer 1 of 2 primary questions:

• Why is this cached? If the information gets stale, why isn’t it updated?
• Why is this not cached? And why is our cache hit rate low?

The Drupal cache system consists of many layers, each of which may contribute to the problem. This tutorial focuses on debugging the Drupal application cache layer, and strategies for debugging Varnish. Given that most external to Drupal layers rely on the use of HTTP headers for caching, you should be able to use similar techniques to those used for debugging Varnish.

In this tutorial, we'll:

• Learn strategies for debugging the Drupal application cache and render cache
• Share strategies for debugging low hit rates when using Varnish

By the end of this tutorial, you should know how to enable and use various cache debugging mechanisms in Drupal to help identify problems in your site performance and resolve them.

Server scaling is the process of adding more resources (CPU, memory, disk space, etc.) to a server (or servers) to help with performance. This might be a single server, or a cluster of different machines. When we talk about server scaling, think more about the resources and less about the specific hardware. Modern servers may not always resemble a physical machine that you can open up and insert additional RAM into. But the theory is the same: more memory means the server can handle more concurrent requests.

Sometimes your Drupal site is optimized, but traffic is still high and takes most of the server’s resources. In order to sustain that load you'll need to scale your server up.

Sometimes you don’t have the resources or expertise to implement caching optimizations, refactoring code, and modifying slow queries -- all of which would improve Drupal's performance. In these cases, you may consider server scaling.

Server scaling can be done in two ways: horizontally or vertically.

In this tutorial we'll:

• Learn what server scaling is
• Discuss examples of both horizontal and vertical server scaling
• Talk about when to choose horizontal versus vertical scaling strategies

By the end of this tutorial, you should understand the concept of server scaling and how it applies to a Drupal application.

No one likes to wait for a slow site to load. Not me, not you, and definitely not search engines. And the effect of site load times on things like SEO, user bounce rates, purchase intent, and overall satisfaction are only going to become more pronounced over time.

Drupal is a modern web framework that is capable of serving millions of users. But every site is unique, and while Drupal tries hard to be fast out of the box, you'll need to develop a performance profile, caching strategy, and scaling plan that are specific to your use case in order to be truly blazing fast.

Drupal site performance depends on multiple components, from hardware setup and caching system configuration to contributed modules, front-end page weight, and CDNs. Experienced Drupal developers looking to optimize their applications know where to start looking for potential savings. They can manipulate settings and combinations of these components to achieve the desired results. Our goal with this set of tutorials is to help explain the process and provide you with the insight that comes with experience.

In this tutorial we'll:

• Introduce high-level performance concepts for Drupal that we'll then cover in more detail elsewhere
• Provide an overview of the main Drupal performance components.

By the end of this tutorial, you should understand what components around your Drupal application are responsible for site performance.

When it's time to start a custom Drupal theme from scratch (especially if you're new to Drupal theming), we recommend using Starterkit. Starterkit helps you get a new theme up and running by scaffolding a set of theme files with sensible defaults, saving you from a bunch of repetitive work.

In this tutorial we'll:

• Learn what Starterkit is
• Discuss when you should--and should not--use Starterkit
• Walk through how to use Starterkit to generate a new Drupal theme

By the end of this tutorial you should be able to explain the use case for Starterkit and understand how to use it to start a new custom theme.

If you want to define a new URL that a user can navigate to, and custom PHP code that will generate the content of the page, you need a route and a controller. Most of the time you'll want to do something more complex than hard code the content of the page. This will require using services in your controller. This can be accomplished in different ways.

In this tutorial we'll:

• Provide the definition for a new route which maps a path to the callback method of a controller class.
• Create a controller that returns a hard coded string.
• Look at examples of using both ControllerBase and dependency injection to access services from a controller, and discuss the benefits of both approaches.

By the end of this tutorial, you should be able to define a new route that maps to a controller and displays content on the page as a result of your custom logic.

The routing system can get dynamic values from the URL and pass them as arguments to the controller. This means a single route with a path of /node/{node} can be used to display any node entity. Route parameters can be validated, and upcast to complex data types via parameter conversion. If you ever want to pass arguments to the controller for a route, you'll use parameters to do so.

In this tutorial we'll:

• Define what parameters (slugs, placeholders) are and what they are used for in a route definition.
• Explain how URL parameters are passed to a controller.
• Define parameter upcasting.

By the end of this tutorial, you should be able to explain how to define a route that uses parameters to pass dynamic values to the route controller, and explain how parameter upcasting works.

Every route should define its access control parameters. When you define routes in a module, you can limit who has access to those routes via different access control options. Route-level access control applies to the path. If your route defines a path like /journey/example, the access control configuration will determine whether to show the current user the page at the path defined by the route, or to have Drupal serve an "HTTP 403 Access Denied" message instead.

In this tutorial we'll look at different ways of adding access control to a route including:

• Access based on the current user's roles and permissions
• Access based on custom logic in a callback method
• Logic in an access checker service

By the end of this tutorial, you should be able to add access control logic to your custom routes that will meet any requirement.

When defining a route and subsequently displaying the page, often we need to calculate the page title based on route parameters or other logic. In these cases, we can't just hard code the value into the _title configuration of the route. To set a dynamic title for a page, we'll use the route's _title_callback option, and point to a PHP callback that contains the logic that computes the title of the page.

In this tutorial we'll:

• Learn how to use the _title_callback route configuration option to dynamically set a page title
• Explain how arguments are provided to the title callback method
• Update the route and controller from a previous tutorial to use a dynamic title callback

By the end of this tutorial, you should be able to configure a route so that its title can be set dynamically using route parameters, instead of hard-coding the title with a static string of text.

Let's write some code that will allow us to see route parameters in action. We'll define a new route with a path like /journey/42/full but where 42 can be any node ID, and full can be any view mode. When a user accesses the path we'll pass the dynamic parameters from the URL to the controller. The controller will then load the corresponding node and render it using the provided view mode, and return that to display on the page.

By the end of this tutorial you should be able to:

• Use dynamic slugs in a route to pass parameters to the route controller.
• See how Drupal will upcast a value like the node ID, 42, to a Node object automatically.
• Explain what happens when you visit a URL that matches a route but the parameters don't pass validation.

By the end of this tutorial, you should be able to pass dynamic values from the URL to a route's controller.

Every web framework, including Drupal, has basically the same job: provide a way for developers to map URLs to the code that builds the corresponding pages. Drupal uses Symfony's HTTPKernel component. Kernel events are dispatched to coordinate the following tasks:

• Process the incoming request
• Figure out what to put on the page
• Create a response
• Deliver that response to the user's browser

Knowing a bit more about how Drupal handles the request-to-response workflow will help you better understand how to use routes and controllers to create your own custom pages or deal with authentication, access checking, and error handling in a Drupal module.

In this tutorial we'll:

• Walk through the process that Drupal uses to convert an incoming request into HTML that a browser can read
• See how the Symfony HTTPKernel helps orchestrate this process
• Learn about how the output from a custom controller gets incorporated into the final page

By the end of this tutorial, you should be able to describe the process that Drupal goes through to convert an incoming request for a URL into an HTML response displayed by the browser.

Sometimes we need the response returned from a controller to be something other than HTML content wrapped with the rest of a Drupal theme. Maybe we need to return plain text, or JSON structured data for an application to consume. Perhaps we need greater control over the HTTP headers sent in the response. This is possible by building on the fact that controllers can return generic Response objects instead of renderable arrays, allowing you to gain complete control over what is sent to the requesting agent.

In this tutorial we'll:

• Look at how to return a plain text response, and JSON data
• Show how to make your responses cacheable by adding cacheability metadata
• Learn about how to use a generic Symfony Response to gain greater control over what gets returned

By the end of this tutorial, you should be able to return responses from a controller in a Drupal module that are not HTML content wrapped in a Drupal theme.

By default, individual forms in Drupal are not output using Twig template files. It's possible to associate a form with a Twig template file by creating a new theme hook, and then referencing that theme hook from the $form array that defines the form. Doing so allows theme developers to customize the layout of the elements in the form using HTML and CSS.

This is useful when you want to change the layout of the entire form. For example, putting the elements into 2 columns. If you want to change individual elements in the form, you can often do so by overriding element specific Twig template files.

In this tutorial, we'll:

• Learn how to create a new theme hook that can be used to theme an element in a render array.
• Associate the $form we want to theme with the new theme hook we created.
• Create a Twig template file for the theme hook that will allow us to lay out the form elements using custom HTML.

By the end of this tutorial, you should be able to associate a Twig template file with any form in Drupal, so that you can customize its layout using HTML and CSS.