What is this

This repo builds an opinionated docker image with a focus on:

• improved security (not running as root)
• prometheus metrics
• opentelemetry tracing
• structured (json) logs
• log obfuscation abilities
• the webserver is specifialised for serving PWA/SPA (static) content
• support for (optional) reverse proxying

Usage

1. Add contents

Add static assets such as your index.html, CSS and images into the /app/content folder

2. (Optionally) adjust Caddy's configuration

Out of the box there is a very simple Caddyfile already installed to /app/Caddyfile. If you need to adjust settings, override this file.

NOTE: The env var $SITE_ADDRESS controls which hostname:port caddy will listen to.

Its default is: :8080

This means that it will respond to any hostname on TCP port 8080

Example Dockerfile:

FROM ghcr.io/ki-insurance/image-caddy

# Override the default Caddyfile (optional)
COPY Caddyfile /app/Caddyfile

# copy in some content (where "build" is a folder containing your assets and "index.html")
COPY build/index.html /app/content

NOTE: this docker image does not run as root. So do not attempt to listen to TCP ports under 1024

OpenTelemetry Demo

There is a sample backend and docker-compose.yaml you can use to see how things work in OpenTelemetry.

To test it out (in the demo directory):

docker-compose up --build

After its launched, you'll want to trigger some traffic. You can do this by visiting: http://localhost:8080

alternatively you can trigger something via some curl

eg: curl localhost:8080/socks/echo

1 out of 10 of the curls should result in a non-200 (and they should be slower also)

Check out the following links

Link	Service	Usage
http://localhost:8080	sample SPA	Simple UI to trigger sample traffic
http://localhost:9411	zipkin	Visualise OpenTelemetry traces
http://localhost:16686	Jaegar	Visualise OpenTelemetry traces

TODO

• integrate and test opentelemetry tracing with caddy
• integrate and test opentelemetry tracing with a demo backend
• test http/json + b3 baggage against OTEL trace collector
• integrate and test opentelemetry metrics (prometheus) with caddy
• improved documentation (Sockshop etc)