Deploy and Host Kroki on Railway

About Hosting Kroki

Kroki provides a unified HTTP API that turns text descriptions into SVG, PNG, PDF, and other diagram formats. This template deploys stable Kroki 0.31.2 privately behind an authenticated Caddy proxy.

Retrieve BASIC_AUTH_USER and the generated BASIC_AUTH_PASSWORD from the proxy service before calling rendering endpoints.

Common Use Cases

Render architecture and dependency diagrams in documentation pipelines
Generate GraphViz, PlantUML, Ditaa, Vega, and WaveDrom assets
Provide a private diagram API for CI and internal tools

Dependencies for Kroki Hosting

Deployment Dependencies

Private Kroki gateway service
Public Caddy authentication proxy
No database or persistent volume

Implementation Details

Railway HTTPS routes to Caddy on port 8080. Caddy enforces generated HTTP Basic credentials, limits source bodies to 2 MB, and forwards requests over Railway private networking to Kroki on port 8000. /healthz checks Kroki's own /health response.

This minimal deployment includes only renderers bundled into the core Kroki image. Optional Mermaid, BPMN, Excalidraw, and diagrams.net companion services are deliberately excluded rather than pretending those formats work.

Why Deploy Kroki on Railway?

Railway provides managed HTTPS, generated credentials, private networking, health checks, and reproducible deployment for a stateless diagram-rendering API.