# cunnie/wildcard-dns-http-server: sslip.io wildcard DNS/HTTP server Dockerfile

# This DNS/HTTP server enables the procurement of wildcard certs for sslip.io
# subdomains. It's meant to be run on the server whose IP address is the
# subdomain. e.g. if the subdomain was '207-44-147-10.sslip.io', then this
# should be run on the server whose IP address is 207.44.147.10, and this will
# procure a wildcard cert for *.207-44-147-10.sslip.io

# This won't work for private addresses such as 10.0.1.10 or 192.168.0.1.

# Dockerfile of a (Golang-based) DNS/HTTP server.

# - the DNS server only responds to TXT queries, and always responds to TXT queries,
#   and always responds with the same TXT record
# - the HTTP server allows you to update the TXT record by POST'ing to the /update
#   endpoint with a JSON body of `{"txt":"the-new-TXT-record"}`. The endpoint
#   is compatible with acme-dns.
# - acme.sh can be configured to update the DNS TXT record via HTTPS.

# To build:

#   DOCKER_BUILD_DIR=$PWD
#   pushd ../src/wildcard-dns-http-server/
#   GOOS=linux GOARCH=amd64 go build -o $DOCKER_BUILD_DIR/wildcard-dns-http-server
#   popd
#   docker build . -f Dockerfile-wildcard-dns-http-server -t cunnie/wildcard-dns-http-server

# Typical start command:

#   docker run -it --rm -p 53:53/udp -p 80:80 cunnie/wildcard-dns-http-server

# To test from host:

#    dig +short txt 127-0-0-1.example.com @localhost
#      "Set this TXT record: curl -X POST http://localhost/update -d  '{\"txt\":\"Certificate Authority's validation token\"}'"
#    curl -X POST http://localhost/update -d '{"txt":"new-TXT-record"}'
#    dig +short txt any-domain-you-want @localhost
#      "new-TXT-record"

FROM alpine AS sslip.io

LABEL org.opencontainers.image.authors="Brian Cunnie <brian.cunnie@gmail.com>"

COPY wildcard-dns-http-server /usr/sbin/wildcard-dns-http-server

ENTRYPOINT ["/usr/sbin/wildcard-dns-http-server"]

# DNS listens on port 53 UDP
# The `EXPOSE` directive doesn't do much in our case. We use it for documentation.
EXPOSE 53/udp
EXPOSE 80/tcp