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One of Sail’s core concepts is the project. Sail projects are like having a machine that has only the required dependencies and configurations included to work on a project. Each Sail project environment is explicitly configured by the project’s engineers, so you can start contributing even quicker.

Imagine the core developers of a source code repo setting up a brand new Linux machine for you. They install the project’s programming language and dependencies. Any configuration that the project requires is already setup. VSCode is installed and configured with all of the extensions helpful to the project. The source code is cloned onto the machine so you can contribute immediately.

A Sail project can be pictured as this cleanly installed and configured machine, except with Sail there is another benefit. That machine can be thrown away and recreated with that exact state as many times as needed.

Dependency and Configuration

A source code repository can specify what dependencies are required by creating a .sail/Dockerfile file in the root of the repo. Sail will build a docker image from this Dockerfile and run the project inside a container running that environment.

If a project doesn’t have a .sail/Dockerfile file, then Sail will try to determine the project’s primary language. If it can determine the language, it will use the language base image from the codercom docker hub. If Sail is unable to determine the language, or a language base image doesn’t exist for the language, then the default codercom/ubuntu-dev image will be used to run the project’s environment.


Since container filesystems are ephemeral by default, Sail clones the project’s repository onto the host at Sail’s $project_root and bind mounts it into the container.

Since the projects are bind mounted into the container, deleting a container does not delete project files and you can seamlessly interact with project files outside of the container.

Host View of the Project

The $project_root is an environment variable that can be set in Sail’s global configuration file, but by default it’s located at ~/Projects. Projects are cloned into the $project_root in a structure like so:


For example, if you were to start a new sail environment to work on sail:

sail run cdr/sail

It would be cloned to $project_root/cdr/sail.

Container View of the Project

By default, the project is bind mounted inside of the container to ~/<repo>

To enable some special-case languages such as Go, the bind mount target location can be configured via the project_root label in your project’s .sail/Dockerfile.

For example:

LABEL project_root "~/go/src/"

Will bind mount the host directory $project_root/<org>/<repo> to ~/go/src/<repo> in the container.


Configuring a project is done through common Dockerfile commands.

For example, if your project has autotools as a dependency, you could install that into your environment through the project’s .sail/Dockerfile like so:

FROM codercom/ubuntu-dev:latest

    autoconf \
    automake \

For specifying things like bind mounts and where a project should be bind mounted to, Sail artificially extends the Dockerfile syntax through labels as seen above in the Container View of the Project.

Sail labels will be described further in Labels.

Developer Configuration

As a developer, you’ll want to bring your own configurations and tooling when working on a project. You can easily extend any project’s environment through the use of a hat. A hat allows you to install your own configurations and tooling on top of each project’s environment through a hat Dockerfile so that you don’t have to leave the workflow you’re used to behind.

Supported Version Control Systems

Currently Sail only supports git.