Contributing

Contributions are welcome. Please open issues and pull requests on the DNS Resolver GitHub repository.

What to contribute

• Bug reports — include the output of docker compose logs dns and your environment variables (redact HOST_IP if needed)
• Feature requests — open an issue describing the use case and the environment variable(s) you would expect
• Template improvements — templates/hosts.tmpl, Corefile.template, zone.template
• entrypoint.sh fixes — POSIX sh only; must run in BusyBox sh (Alpine)

Development setup

git clone https://github.com/circle-rd/dns-resolver.git
cd dns-resolver

# Build the image locally
docker build -t dns-resolver:dev .

# Run with test environment variables — prints the generated Corefile and exits
docker run --rm \
  -e DOMAIN=test.local \
  -e HOST_IP=127.0.0.1 \
  dns-resolver:dev sh -c '
    DOMAIN=test.local HOST_IP=127.0.0.1 /templates/entrypoint.sh &
    sleep 2
    cat /etc/coredns/Corefile
    kill %1
  '

Testing DNS resolution locally

# Start with a test config
docker run --rm \
  -e DOMAIN=test.local \
  -e HOST_IP=127.0.0.1 \
  -p 5353:53/udp \
  -v /var/run/docker.sock:/var/run/docker.sock:ro \
  dns-resolver:dev

# In another terminal
dig @127.0.0.1 -p 5353 anything.test.local A +short
# → 127.0.0.1

Code style

• Entrypoint: POSIX sh (#!/bin/sh) — no bashisms
• Templates: CoreDNS config syntax + Go text/template (hosts.tmpl)
• No new environment variables without updating README.md, .env.example, and the documentation

Reporting security issues

Please use the GitHub repository security advisories feature — do not open public issues for security vulnerabilities.