When writing containers for a local development environment, security is often a lesser concern. This is fine as long as we never intend to put the containers we create in a production environment.

When we do want to make production-ready containers, however, our priorities change. While Docker tries to be secure by default, it can't protect us from badly configured or vulnerable applications. For that, we need to design our images to be more secure.

In this tutorial, we'll:

• Outline the best practices for writing secure container images
• Introduce the USER directive
• Set file ownership using COPY and ADD
• Use the RUN directive to set file permissions

Getting Drupal to run in Docker requires a lot of moving parts. After installing Docker and Docker Compose, we need to select a collection of containers from Docker Hub and create a new docker-compose.yml file. Once we have environment variables and volumes configured, this only gives us the capability of running a Drupal site in Docker.

What if we already have a Drupal site we want to develop using Docker? In this tutorial, we'll show how to modify an existing project to minimize the setup time necessary for switching to a Docker-based environment.

In this tutorial, we'll:

• Describe the best practices for project organization.
• Use an environment file to configure containers.
• Add a Docker-specific settings.php file.

Dockerizing a project helps to simplify setting up new developer workstations, and on-boarding new team members. All the pieces of infrastructure necessary to get started are all in the Compose file. Yet, it's not as easy as it could be.

We still need to create a settings.local.php file with all the necessary database connection information and any setting overrides. In this tutorial, we'll move those out of the local settings file and into a Docker specific settings file that ships with all that information pre-configured out of the box.

In this tutorial, we'll:

• Explain the motivation behind having a Docker-specific settings file.
• Describe how to modify settings.php to detect when it's in a Docker environment.
• Create a Docker-specific settings file with everything preconfigured.

One of the problems with Dockerizing an existing project is that configuration information tends to proliferate everywhere. Not only do we have settings in docker-compose.yml, but also in our Docker-specific settings file settings.docker.php. If we change a setting in one place we need to copy and paste it everywhere else. This can make things difficult if we suddenly have the need to change a setting.

Fortunately, there's a way to centralize Docker configuration for our project by using an environment file.

In this tutorial, we'll:

• Review what an environment file is and its format.
• List the advantages of moving Docker configuration to an environment file.
• Describe the .env file, and how it provides us further advantages.

Throughout this series we've been focused on working with a single set of containers and a single site. For most Drupal developers, however, we're expected to work with multiple client sites, sometimes several different ones in the same day.

When we add Docker into the mix, it can seem overwhelmingly complicated when you're used to working with other tools. Fortunately, there are several simple practices that not only work well with Docker, but also support your workflow.

In this tutorial, we'll:

• Outline the best practices when building a local development environment in Docker.
• Compare the differences in workflow when using Docker compared to other local development environments.
• Discuss various strategies to reduce resource use on team workstations.

Today's Drupal sites often rely upon external services in order to serve their visitors. When hosting such a site in Docker, we need to take special consideration in order to allow the site to access these essential components.

In this tutorial, we'll:

• Outline the steps necessary for troubleshooting connectivity issues
• Discuss steps to protect API keys and other sensitive pieces of information
• Touch upon your options if you require external libraries or utilities

One of the key advantages of Docker is that it makes it much easier to share your containers with your team members. For most of this series, we've been relying on containers hosted on Docker Hub. When we need to create a custom container for our team, we want to leverage that same sharing infrastructure.

In this tutorial, we'll:

• Describe the various methods of sharing containers.
• Outline the advantages of using Docker Hub.
• Briefly describe why and when you should use a private container image registry.

For many container images on Docker Hub, the preferred approach is to create an automatic build. An automatic build integrates Hub with a public Git repository, providing you an effective, open, and best-practice approach to sharing your containers with your team, and with the world.

In this tutorial, we'll:

• List the advantages of creating an automatic build compared to other approaches on Docker Hub.
• Describe the process of creating an automatic build.
• Outline how to organize your git repository for your images.
• Learn how to configure and trigger the build on Hub.

Often it's useful for a container image to provide several variants of itself under the same name on Docker Hub. Docker uses tags to identify these variants. You can configure your own tags as part of your automatic build on Docker Hub.

In this tutorial, we'll:

• Outline the uses for tags
• Discuss the best practices for tag names
• Learn how to add tags to your automatic build on Docker Hub

Docker Hub provides a free, easy to use way of distributing your container images. However, there are situations where sharing your container images is either not ideal, bad practice, or against legal requirements. In those cases, you will want to use a private registry instead.

In this tutorial, we'll:

• Describe what a private registry is.
• Learn how to run Docker's own registry image.
• Learn how to push and pull images from the self-hosted registry.
• Outline the production concerns for the registry image.
• List other options for self-hosting your own images.

Docker provides numerous advantages for us as Drupal developers. It simplifies the management of infrastructure for our projects while allowing customization to suit each project's needs. Running Docker in production also brings a number of advantages, but it also creates new concerns.

In this tutorial, we'll:

• Outline the advantages Docker brings to the production environment.
• Highlight the concerns when planning a production deployment of Docker.
• Describe container orchestration and list several container orchestration platforms to choose from.

Media source plugins provide the link between media entities in Drupal and the actual media asset itself. They are the code that understand the difference between an image, a video, and a Tweet, and perform the translation that allows the media ecosystem to treat all media entities equally. For example, local image files, and remote YouTube videos, can both be catalogued in a similar way as media entities, but they need very different handling when it comes to displaying them.

Media sources are represented as plugins, there are a handful in Drupal core, and a developer can add new plugins to represent any type of media your application needs to catalogue.

In this tutorial we'll learn:

• How media source plugins relate to Media Types
• The responsibilities of a media source plugin

By the end of this tutorial you should be able to define the role of a media source plugin and understand what's required to define your own.

The Drupal core Media Library module provides an enhanced user interface for locating Media entities and attaching them to an article. It's a drop-in replacement for the default entity reference widget which uses a not very intuitive autocomplete field. Using the Drupal core Media Library module requires minimal configuration.

If you want to provide content creators with a gallery-like library of Media entities that they can browse through in order to find the ones they want to add to their content, the Media Library is the easiest way to do it. It can be configured to work with both Media fields and the CKEditor powered WYSIWYG editor commonly used for editing the body field of Drupal nodes. There's really no reason not to use it.

In addition to providing a better UI for locating existing Media entities, the Media Library provides a way to create new Media entities right from the content creation form. This prevents an otherwise confusing requirement where Media entities need to be created, via a different set of forms, before they can be used.

In this tutorial we'll:

• Install and configure the Media Library module to work with Media fields
• Use the user interface provided by the Media Library to improve the experience of finding and selecting Media entities to associate with a piece of content

By the end of this tutorial you'll know how to replace the default entity reference widget used for selecting Media entities with the much improved Media Library UI.

Media entities, like any content entity, work great with all the different features Drupal provides for changing the way things are displayed: view modes, Layout Builder, theme templates, and more. We're big fans of using view modes to create a component-like design system where entity types have view modes representing the different context in which they're displayed. Then we theme the view modes. This works great for displaying Media entities associated with a page and for changing the way that Media assets are displayed within the Media Library browser.

In this tutorial we'll:

• Create Hero and Sidebar view modes for Media entities
• Configure the Image Media type to use the new view modes and style each one differently
• Use the new view modes to render Image Media assets within a Layout
• Update the Media library view mode that's used by the Media Library browser to display additional information alongside the thumbnails used when selecting Media to attach to a page

By the end of this tutorial you should be able to change the way that Media assets are displayed by using view modes and display formatters in a Drupal site.

It's not uncommon to patch, or customize, contributed modules during the lifetime of a site. It's important to know if you've done so when planning for a migration since you'll want to be sure that you don't lose any customizations when you start using an updated version of a module.

In this tutorial we will walk through using the Hacked! module to check for any alterations to your Drupal code base.

The Drupal-to-Drupal migration system is still a work in progress. As such, there are a few things that simply don't work, and a few others that still have kinks to be ironed out. In this tutorial, we'll look at some of the common hang-ups that we've encountered, the status of resolving those issues, and what your options are in the meantime.

In Drupal, there are 3 modules in core related to migration that you'll want to know about. These modules can help you import data into Drupal from disparate sources, or upgrade from a previous version of Drupal.

In this tutorial we'll look at what each of these core migration modules do, and talk about when you'll need to use them.

Drupal core provides support for migrating data from Drupal 6 or 7. The templates provided in core migrate your data in a very specific way. They attempt to copy things verbatim whenever possible. However, you may wish to alter this for your migrations. In this tutorial we are going to explore the various ways that you can alter the existing Drupal-to-Drupal migrations to meet your needs.

One method of creating a custom Drupal-to-Drupal migration involves using the Migrate Upgrade module to generate a set of migration configuration entities that you can use as a starting point. Even if you're not going to use the generated output in the end, this is still an informative exercise as it allows you to see examples of various migration paths.

In this tutorial we'll:

• Use the Migrate Upgrade module's Drush commands to import Drupal core's migration templates
• Examine the generated configuration entities
• Use the Migrate Tools module's Drush commands to view a list of the individual migrations that make up our Drupal-to-Drupal migration

By the end of this tutorial, you should be able to use the Migrate Upgrade module to generate the migrations that Drupal core would use to migrate content, list those migrations, and inspect them individually.

If you want to modify the Drupal-to-Drupal migrations created by Migrate Upgrade you'll need to export the Migrate Plus configuration entities, convert the ones you want to customize to standard migration .yml files, and put them into a custom module. Then, you can make edits the YAML definition of the migration, and keep your customizations in Git.

We recommend creating a new module to house the code that makes up your custom Drupal-to-Drupal migration.

In this tutorial we'll:

• Create a new module
• Export the migration configuration entities generated by drush migrate-upgrade as YAML files
• Copy the files that represent the migrations we're interested in into our new module
• Customize the copied files

By the end of this tutorial you should have a new module that contains the starting migration YAML files for your custom migration.