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How DDEV Works

The easiest way to think about how DDEV works is to think of it as a set of little networked computers (docker containers). You can think of them as being in a different network world than your workstation computer, but reachable from there.

When you install or upgrade DDEV you're mostly installing a single binary, named ddev. When you use it, it downloads the Docker images it needs, and then starts them based on your project's needs.

  • The ddev-webserver container (one per project) runs nginx or apache and php-fpm for a single site, so it does all the basic work of a PHP-interpreting webserver.
  • The ddev-dbserver container (one per project) handles MariaDB/MySQL/Postgresql database management. It can be reached from the webserver by the hostname db or with the more explicit name ddev-<projectname>-db.
  • The optional dba container runs PhpMyAdmin for projects with MySQL or MariaDB.
  • Additional add-on services may be there for a given project, for example solr or elasticsearch or memcached.

Although it's not common usage, different projects can communicate with each other as described in the FAQ

Now for the two oddball containers, which are global (there is only one of each).

  • The ddev-router container is a "reverse proxy". It takes incoming HTTP/S requests and looks up the hostname in the incoming URL and routes it to the correct project's ddev-webserver. Depending on the project's configuration with additional_hostnames and additional_fqdns it can route many different URLs to a single project's ddev-webserver. If like most people you use the named URLs (like then your request goes through the router. When you use the URLs, the requests go directly to the ddev-webserver.
  • The ddev-ssh-agent container runs an ssh-agent inside the docker network so that after you do a ddev auth ssh all the different projects can use your ssh keys for outgoing requests (like private composer access or scp from a remote host).

Here's a basic diagram of how it works inside the docker network:

DDEV Docker Network Architecture

Last update: August 30, 2022