feat: add install script fo avahi daemon

README.md

@@ -67,3 +67,41 @@ alerts using `alerts.clear`.
 
 Alerts are sent only as part of telemetry, so in order to report device alert,
 use `send_telemetry` with any payload.
+
+## Running your own VUCM via Docker
+
+A simple Dockerfile can be:
+```
+FROM python:3.10-alpine3.16
+
+WORKDIR /app
+
+COPY requirements.txt requirements.txt
+RUN python -m venv .venv
+RUN .venv/bin/pip install -r requirements.txt
+
+COPY script.py script.py
+
+CMD [".venv/bin/python", "script.py"]
+```
+
+### Note about Enapter Gateway
+
+If you are using [Enapter Gateway](https://handbook.enapter.com/software/gateway_software/), you should use debian base Docker image and run [`avahi`](https://wiki.debian.org/Avahi) to resolve gateway host name:
+```diff
+-FROM python:3.10-alpine3.16
++FROM python:3.10-buster
+
+WORKDIR /app
++
++RUN curl -sSfL https://raw.githubusercontent.com/Enapter/python-sdk/main/extenstions/avahi-debian/install.sh | sh -s
++ENTRYPOINT ["bash", "./entrypoint.sh"]
+
+COPY requirements.txt requirements.txt
+RUN python -m venv .venv
+RUN .venv/bin/pip install -r requirements.txt
+
+COPY script.py script.py
+
+CMD [".venv/bin/python", "script.py"]
+```

extenstions/avahi-debian/install.sh

@@ -0,0 +1,28 @@
+#!/bin/sh
+set -e
+
+apt-get update && apt-get install -y --no-install-recommends avahi-daemon libnss-mdns
+
+# allow hostnames with more labels to be resolved. so that we can
+# resolve node1.mycluster.local.
+# (https://github.com/lathiat/nss-mdns#etcmdnsallow)
+echo '*' > /etc/mdns.allow
+
+# Configure NSSwitch to use the mdns4 plugin so mdns.allow is respected
+sed -i "s/hosts:.*/hosts:          files mdns4 dns/g" /etc/nsswitch.conf
+printf "[server]\nenable-dbus=no\n" >> /etc/avahi/avahi-daemon.conf
+chmod 755 /etc/avahi/avahi-daemon.conf
+mkdir -p /var/run/avahi-daemon
+chown avahi:avahi /var/run/avahi-daemon
+chmod 755 /var/run/avahi-daemon
+
+cat <<EOF > entrypoint.sh
+#!/bin/bash
+
+set -e
+
+avahi-daemon --daemonize --no-drop-root
+
+exec "\$@"
+EOF
+chmod 755 entrypoint.sh