docs: add example Dockerfile

docs/Dockerfile

@@ -0,0 +1,15 @@
+FROM alpine:3.12
+
+EXPOSE 5353 8080
+
+ENV VERSION=3.0.0
+
+RUN apk --no-cache add openssl ca-certificates && \
+    apk --no-cache add ruby ruby-etc ruby-io-console ruby-json ruby-webrick && \
+    apk --no-cache add --virtual .build-deps ruby-dev build-base tzdata && \
+    gem install --no-document dyndnsd -v ${VERSION} && \
+    # set timezone to Berlin
+    cp /usr/share/zoneinfo/Europe/Berlin /etc/localtime && \
+    apk del .build-deps
+
+ENTRYPOINT ["dyndnsd", "/etc/dyndnsd/config.yml"]

docs/debian-6-init-dyndnsd

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+#! /bin/sh
+### BEGIN INIT INFO
+# Provides:          dyndnsd
+# Required-Start:    $remote_fs $syslog
+# Required-Stop:     $remote_fs $syslog
+# Default-Start:     2 3 4 5
+# Default-Stop:      0 1 6
+# Short-Description: Handle dyndnsd.rb gem
+### END INIT INFO
+
+# using the system ruby's gem binaries directory
+DAEMON="/var/lib/gems/1.8/bin/dyndnsd"
+
+CONFIG_FILE="/opt/dyndnsd/config.yaml"
+
+DAEMON_OPTS="$CONFIG_FILE"
+
+test -x $DAEMON || exit 0
+
+. /lib/lsb/init-functions
+
+case "$1" in
+  start)
+    log_daemon_msg "Starting dyndnsd.rb" "dyndnsd"
+    start-stop-daemon --start --quiet --oknodo --make-pidfile --pidfile "/var/run/dyndnsd.pid" --background --exec $DAEMON -- $DAEMON_OPTS
+    log_end_msg $?
+    ;;
+  stop)
+    log_daemon_msg "Stopping dyndnsd.rb" "dyndnsd"
+    start-stop-daemon --stop --quiet --oknodo --pidfile "/var/run/dyndnsd.pid"
+    log_end_msg $?
+    ;;
+  restart|force-reload)
+    log_daemon_msg "Restarting dyndnsd.rb" "dyndnsd"
+    start-stop-daemon --stop --quiet --oknodo --retry 30 --pidfile "/var/run/dyndsd.pid"
+    start-stop-daemon --start --quiet --oknodo --make-pidfile --pidfile "/var/run/dyndnsd.pid" --background --exec $DAEMON -- $DAEMON_OPTS
+    log_end_msg $?
+    ;;
+  *)
+    log_action_msg "Usage: $0 {start|stop|restart|force-reload}"
+    exit 2
+    ;;
+esac