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How DDEV Works

It’s easiest to think of DDEV as a set of little networked computers (Docker containers) that are in a different network from your workstation but still reachable from it.

When you install or upgrade DDEV you’re mostly installing a single ddev binary. When you use it, it downloads the Docker images it needs, and then starts them based on what’s needed for your projects.

  • 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 web server.
  • The ddev-dbserver container (one per project) handles MariaDB/MySQL/PostgreSQL database management. It can be reached from the web server 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 global containers (there’s only one of each):

  • The ddev-router container is a “reverse proxy”. It takes incoming HTTP/S requests, 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 https://something.ddev.site, your request goes through the router. When you use the 127.0.0.1 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: October 15, 2022