Configuration

go-dims is configured entirely through environment variables. This makes it portable, deployment-friendly, and easy to integrate into Docker, AWS Lambda, or other runtime environments.

There are very few required settings — most are optional and designed to give you control over how images are processed, cached, and served.

🚀 Quick Start

You can set configuration values inline when starting the server:

DIMS_SIGNING_KEY="mysecret" DIMS_ERROR_BACKGROUND="#ffffff" ./dims serve

Or define them in an .env file or through your platform’s configuration system (e.g., Docker Compose, AWS Lambda environment variables, etc.).

✅ Required Setting

Variable	Description
DIMS_SIGNING_KEY	Secret key used to verify signed URLs. Required.

🔧 Configuration Areas

Configuration is organized into logical sections. Each section has its own detailed documentation:

• 📌 General Configuration: Logging, error images, timeouts, and runtime behavior.
• 🧠 Cache Control: HTTP cache headers like Cache-Control, Expires, and Last-Modified.
• 🧪 Image Compression: JPEG, PNG, and WebP output tuning.
• 📡 Image Sources: Configure sources like HTTP, S3, and local files.
• 🚚 Migrating from mod_dims: Migration guide for mod_dims users.

Tips

All values are read once during startup.

Booleans should be set as true or false.

Lists (e.g., excluded formats) are comma-separated: DIMS_EXCLUDED_OUTPUT_FORMATS=tiff,gif

If you're deploying go-dims in production, we recommend using environment-specific secrets managers to safely handle values like DIMS_SIGNING_KEY.