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Docker in environments

Standard Coder environments run as normal Docker containers. This carries limitations as to what applications you can run inside your environment. Most notably, it's not possible to run Docker securely within normal Docker containers.

Coder offers an alternative environment deployment option that allows you to run Docker, Docker Compose, systemd, and other system-level applications securely within your development containers. We call this environment variant a Container-based Virtual Machine (CVM).

Are you a platform admin? Learn how to enable Docker in environments for your deployment.

Container-based Virtual Machine (CVM)

By choosing this option, your environment behaves like a VM or raw host, yet retains the image, security, and performance properties of typical containers.

To create an environment capable of securely running system-level applications like Docker, check the Run as Container-based Virtual Machine box when you create a new environment.

Create CVM

Disk

Standard environments only persist the /home directory in your environment disk. CVM environments have additional levels of persistence:

  1. /var/lib/docker is stored in your environment disk and is persisted between rebuilds. This prevents shutdowns and rebuilds from purging the Docker cache.

  2. The environment image is itself stored in your environment disk. Note that this data is never directly accessible to you but will still consume data on your disk and count towards the size limit.

When setting default disk sizes for images, plan for these additional storage requirements. We recommend treating the environment as a full machine, so disk sizes in the range of 50-100 GB are reasonable. This is especially true if users of the image are storing large Docker caches.

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