Image Management

While Coder provides example base container images for workspaces, it's often best to create custom images that matches the needs of your users. This document serves a guide to operational maturity with some best practices around managing workspaces images for Coder.

1. Create a minimal base image
2. Create golden image(s) with standard tooling
3. Allow developers to bring their own images and customizations with Dev Containers

Note: An image is just one of the many properties defined within the template. Templates can pull images from a public image registry (e.g. Docker Hub) or an internal one., thanks to Terraform.

Create a minimal base image

While you may not use this directly in Coder templates, it's useful to have a minimal base image is a small image that contains only the necessary dependencies to work in your network and work with Coder. Here are some things to consider:

• curl, wget, or busybox is required to download and run the agent
• git is recommended so developers can clone repositories
• If the Coder server is using a certificate from an internal certificate authority (CA), you'll need to add or mount these into your image
• Other generic utilities that will be required by all users, such as ssh, docker, bash, jq, and/or internal tooling
• Consider creating (and starting the container with) a non-root user

See Coder's example base image for reference.

Create general-purpose golden image(s) with standard tooling

It's often practical to have a few golden images that contain standard tooling for developers. These images should contain a number of languages (e.g. Python, Java, TypeScript), IDEs (VS Code, JetBrains, PyCharm), and other tools (e.g. docker). Unlike project-specific images (which are also important), general purpose images are great for:

• Scripting: Developers may just want to hop in a Coder workspace to run basic scripts or queries.
• Day 1 Onboarding: New developers can quickly get started with a familiar environment without having to browse through (or create) an image
• Basic Projects: Developers can use these images for simple projects that don't require any specific tooling outside of the standard libraries. As the project gets more complex, its best to move to a project-specific image.
• "Golden Path" Projects: If your developer platform offers specific tech stacks and types of projects, the golden image can be a good starting point for those projects.

This is often referred to as a "sandbox" or "kitchen sink" image. Since large multi-purpose container images can quickly become difficult to maintain, it's important to keep the number of general-purpose images to a minimum (2-3 in most cases) with a well-defined scope.

Examples:

• Universal Dev Containers Image

Allow developers to bring their own images and customizations with Dev Containers

While golden images are great for general use cases, developers will often need specific tooling for their projects. The Dev Container specification allows developers to define their projects dependencies within a devcontainer.json in their Git repository.

• Learn how to integrate Dev Containers with Coder