Architecture

This document provides a high level overview of Coder's architecture.

Diagram

coderd

coderd is the service created by running coder server. It is a thin API that connects workspaces, provisioners and users. coderd stores its state in Postgres and is the only service that communicates with Postgres.

It offers:

• Dashboard (UI)
• HTTP API
• Dev URLs (HTTP reverse proxy to workspaces)
• Workspace Web Applications (e.g easily access code-server)
• Agent registration

provisionerd

provisionerd is the execution context for infrastructure modifying providers. At the moment, the only provider is Terraform (running terraform).

By default, the Coder server runs multiple provisioner daemons. External provisioners can be added for security or scalability purposes.

Agents

An agent is the Coder service that runs within a user's remote workspace. It provides a consistent interface for coderd and clients to communicate with workspaces regardless of operating system, architecture, or cloud.

It offers the following services along with much more:

• SSH
• Port forwarding
• Liveness checks
• startup_script automation

Templates are responsible for creating and running agents within workspaces.

Service Bundling

While coderd and Postgres can be orchestrated independently,our default installation paths bundle them all together into one system service. It's perfectly fine to run a production deployment this way, but there are certain situations that necessitate decomposition:

• Reducing global client latency (distribute coderd and centralize database)
• Achieving greater availability and efficiency (horizontally scale individual services)

Workspaces

At the highest level, a workspace is a set of cloud resources. These resources can be VMs, Kubernetes clusters, storage buckets, or whatever else Terraform lets you dream up.

The resources that run the agent are described as computational resources, while those that don't are called peripheral resources.

Each resource may also be persistent or ephemeral depending on whether they're destroyed on workspace stop.