This guide is intended as a list of best practices to follow when professionally deploying Shopware shops.
Professional deployment begins with professional development. The time when everybody edited files on a central FTP server are long gone.
If you find yourself reusing plugins, themes or configuration, think about using Composer and the Shopware Composer Project for your new projects. It will help you to require plugins or libraries you repeatedly use.
Even if some feature works perfectly on the developers own machine, there is always a chance that some setting or the integration with some feature of another developer breaks the shop. So it is a good idea to have one or more stages of integrations; a common pattern is a three level system of development, staging and production systems. Of course all these are just a recommendation - all of this can and should be modified to your situation, use cases and workflows.
The development system is where a first check is possible or where internal stakeholders can get a preview or glimpse of how a feature is about to be developed.
The staging system is where a thoroughly tested feature is being shown to an external customer and features are combined into releases.
The production system is what the end customer get's to see. If a staging system contains all relevant features for e.g. a certain milestone, these can be deployed together to this system.
Deployments should be as automatic as possible to prevent any chance of human error. It is generally a good idea to not simply replace or update your webroot on the production system. Rather create a fresh clone of the latest production release from your VCS, maybe run some automated tests to make sure no basic errors occured and just switch the webroot of your webserver to point to your new release. Shared resources (like images, documents etc.) can be offloaded to a CDN or themselves be included in your webroot by file system links.
Should anything be wrong with this release, you can still switch back to the old version (given the database wasn't modified in a destructive way). This way you can minimize the downtime, or even eliminate it all together if you're working in a cluster setup and are able to update machine by machine.
The ability to upgrade/downgrade your production environment is commonly known as "Blue-Green Deployment". Starting with v5.4 forward, Shopware commits itself to be able to support this kind of deployment out-of-the-box for succeeding minor versions. This means that you can confidently deploy a coming v5.5 release, knowing you can always switch back to your current proven v5.4. Of course this presumes that all installed plugins support this as well.
So any deprecations to the database that were announced in v5.4 will only be applied in a v5.6 release. That way the intermediate v5.5 can and must support both a v5.4 and a v5.5 database. Database deprecations in v5.5 will be applied in a v5.7 and so on.
Try to not store credentials on disk to minimize the information an attacker might gain in case of file system access. Rather use environment variable set e.g. in the webserver. The Shopware Composer Project supports environment variable for the setup of e.g. the database out of the box.
You could start your automated deployments with some simple shell scripts to e.g. checkout a specific tag on the server or switch the currently productive version by changing the target of the webroot-link. You could re-utilize these scripts later by integrating them into a CI/CD system like Jenkins, Bamboo or others.
It is often also a good idea to redefine basic settings which could be changed by users to sane defaults with each deploy. Examples could be the mailer configuration, thumbnail sizes or controller caching times for the HTTP cache.