Initial commit for creating core dns image

Dockerfile

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+FROM alpine:edge
+
+RUN apk --no-cache add dnsmasq
+
+EXPOSE 53/udp
+EXPOSE 67/udp
+EXPOSE 68/udp
+
+RUN mkdir -p /etc/dnsmasq.d/config
+COPY dns.conf /etc/dnsmasq.d/               && \
+     dhcp-conf /etc/dnsmasq.d/              && \
+     dhcp-reservations.conf /etc/dnsmasq.d/ && \
+     hosts.local /etc/dnsmasq.d/ 	    && \
+
+COPY entrypoint.sh /
+
+ENTRYPOINT ["/entrypoint.sh"]

dhcp-reservations.conf

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+# file: dhcp-reservations.conf
+# description: This file is for setting DHCP reservations (static DHCP entries)
+
+# Set DHCP Reservations Here
+# Reservations follow the format below, and the IP address does not need to fall
+# within one of the ranges you've defined in your dnsmasq.conf, it must only be
+# valid for the specified network.
+#
+#    dhcp-host=<mac_address>,<ip_address>,<hostname>,<leasetime>
+#      (you can use 'infinite' for leasetime, or specify in hours like 12h)
+#

dhcp.conf

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+# file: dhcp.conf
+# description: This file is for user configuration of the dhcp service on dnsmasq.
+
+###                    ###
+### DHCP Configuration ###
+###                    ###
+
+# Set up scopes
+# dhcp-range=<range_name>,<start_address>,<end_address>,<subnet_mask>,<lease_time>
+#dhcp-range=home_lan,192.168.1.100,192.168.1.200,255.255.255.0,12h
+
+# Set Gateway Servers (the 3 tag means 'router')
+#dhcp-option=home_lan,3,192.168.1.1
+
+# Set DNS servers (the 6 tag means 'dns-server')
+# dhcp-option=<range_name>,6,<dns_server_address>
+# range_name is defined above when you defined your ranges.
+#dhcp-option=home_lan,6,10.0.0.10

dns.conf

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+# file: dns.conf
+# description: This file is for user configuration of the dns service on dnsmasq.
+
+###                   ###
+### DNS Configuration ###
+###                   ###
+
+# Turn off reading of the local /etc/resolv.conf file
+# We're setting our upstream servers below, so reading resolv.conf is
+# unncecessary
+no-resolv
+
+# Read hosts from here in addition to /etc/hosts
+#addn-hosts=/etc/hosts.mydomain
+addn-hosts=/etc/dnsmasq.d/hosts.local
+
+# Add your upstream DNS servers here. You can set as many as you'd like.
+# If you don't want to use Quad9 as your upstream provider, replace
+# these with servers of your own choosing.
+server=9.9.9.9
+server=142.112.112.112
+
+# Never forward plain names (without a dot or domain part)
+domain-needed
+
+# Never forward addresses in the non-routed address spaces.
+bogus-priv
+
+# Add local-only domains here, queries in these domains are answered
+# from /etc/hosts or DHCP only.
+#local=/localnet/
+#local=/internal.example.com/
+
+# Set your internal domain
+#domain=internal.example.com
+ 
+# Expand hosts using 'domain' set above. 
+expand-hosts
+
+# Set logging facility
+# If there is at least one / in the log-facility, it will be treated
+# as a file. dnsmasq will close and reopen the file when it receives
+# signal USR2, which allows for log rotation without stopping dnsmasq.
+# You'll want to set a bind mount to access this file on your local host
+# and manage it's logs using logrotate.
+log-facility=/var/log/dnsmasq/dnsmasq.log
+
+# Turn on query logging. Be warned, this can eat up disk space
+# quickly.
+#log-queries

entrypoint.sh

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+#!/bin/sh
+
+dnsmasq -k &
+
+FILE="/etc/dnsmasq.d/hosts.local"
+LAST=`md5sum "$FILE"`
+while true; do
+  sleep 0.1
+  NEW=`md5sum "$FILE"`
+  if [ "$NEW" != "$LAST" ]; then
+        killall -s SIGHUP dnsmasq
+    LAST="$NEW"
+  fi
+done

hosts.local

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+# file: hosts.local
+# description: This file is for setting static DNS entries in dnsmasq. Each line should begin with an IP address, followed by a FQDN.
+#              Additional terms will be treated as CNAME records (i.e., pointers back to the FQDN).
+#
+
+# 192.168.1.100   example-host1.internal.example.com    example-host1   example-web1