Initial code commit

Author: robinsmidsrod

.gitignore

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+/data

Dockerfile

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+FROM ubuntu
+
+MAINTAINER Robin Smidsrød <[email protected]>
+
+RUN apt-get -q -y update \
+ && apt-get -q -y -o "DPkg::Options::=--force-confold" -o "DPkg::Options::=--force-confdef" dist-upgrade \
+ && apt-get -q -y -o "DPkg::Options::=--force-confold" -o "DPkg::Options::=--force-confdef" install isc-dhcp-server man \
+ && apt-get -q -y autoremove \
+ && apt-get -q -y clean \
+ && rm -rf /var/lib/apt/lists/*
+
+COPY util/my_init.py /sbin/my_init
+COPY util/entrypoint.sh /entrypoint.sh
+ENTRYPOINT ["/entrypoint.sh"]

LICENSE

@@ -186,7 +186,7 @@
       same "printed page" as the copyright notice for easier
       identification within third-party archives.
 
-   Copyright {yyyy} {name of copyright owner}
+   Copyright 2015 Robin Smidsrød <[email protected]>
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.

README.md

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+Docker image for ISC DHCP server
+================================
+
+This Docker image is suitable for running a DHCP server for your docker host
+network.  It uses ISC DHCP server which is bundled with the latest Ubuntu
+LTS distribution.
+
+How to build
+============
+
+ 1. Install Docker with the instructions on <https://www.docker.com>.
+ 2. Run `./build` to create the local image `dhcpd`.
+
+How to use
+==========
+
+The most common use-case is to provide DHCP service to the host network of
+the machine running Docker.  For that you need to create a configuration for
+the DHCP server, start the container with the `--net=host` docker run
+option and specify the network interface you want to provide DHCP service
+on.
+
+ 1. Create `data` folder.
+ 2. Create `data/dhcpd.conf` with a subnet clause for the specified
+    network interface.  If you need assistance, you can run
+    `docker run -it --rm dhcpd man dhcpd.conf` for a description of
+    the configuration file syntax.
+ 3. Run `docker -it --rm --net=host -v "$(pwd)/data":/data dhcpd eth0`.
+    `dhcpd` will automatically start and display its logs on the console.
+    You can press Ctrl-C to terminate the server.
+
+A simple `run` script is also included which makes it quick to iterate on a
+configuration until you're satisfied.
+
+Notes
+=====
+
+The entrypoint script in the docker image takes care of running the DHCP
+server as the same user that owns the `data` folder.  This ensures that the
+permissions on the files inside the `data` folder is kept consistent.  If
+the `data` folder is owned by root, dhcpd is run as the normal dhcpd user.
+
+If you forget to run the docker container with the `--net=host` option a
+warning will be emitted informing you that you've probably forgotten it.
+
+If a `/data` volume is not provided with a `dhcpd.conf` inside it, the
+container will exit early with an error message.
+
+Acknowledgements
+================
+
+This image uses the following software components:
+
+ * Ubuntu Linux distribution from <https://www.ubuntu.com>.
+ * ISC DHCP server from <https://www.isc.org/downloads/dhcp/>.
+ * Docker-optimized my_init from <https://github.com/phusion/baseimage-docker>.
+
+Copyright & License
+===================
+
+This project is copyright 2015 Robin Smidsrød <[email protected]>.
+
+It is licensed under the Apache 2.0 license.
+
+See the file LICENSE for full legal details.

build

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+#!/bin/bash
+docker build -t dhcpd "$@" $(dirname $0)

run

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+#!/bin/bash
+pushd $(dirname $0) >/dev/null
+data_dir="$(pwd)/data"
+docker run -ti --rm --net host -v "$data_dir":/data dhcpd "$@"
+popd >/dev/null

util/entrypoint.sh

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+#!/bin/bash
+set -e
+
+# Single argument to command line is interface name
+if [ -n "$1" ]; then
+    if [ -e "/sys/class/net/$1" ]; then
+        IFACE=$1
+    fi
+fi
+
+# No arguments mean all interfaces
+if [ -z "$1" ]; then
+    IFACE=" "
+fi
+
+init="/sbin/my_init --skip-startup-files --skip-runit"
+
+if [ -n "$IFACE" ]; then
+    # Run dhcpd for specified interface or all interfaces
+
+    data_dir="/data"
+    if [ ! -d "$data_dir" ]; then
+        echo "Please ensure '$data_dir' folder is available."
+        echo 'If you just want to keep your configuration in "data/", add -v "$(pwd)/data:/data" to the docker run command line.'
+        exit 1
+    fi
+
+    dhcpd_conf="$data_dir/dhcpd.conf"
+    if [ ! -r "$dhcpd_conf" ]; then
+        echo "Please ensure '$dhcpd_conf' exists and is readable."
+        echo "Run the container with arguments 'man dhcpd.conf' if you need help with creating the configuration."
+        exit 1
+    fi
+
+    uid=$(stat -c%u "$data_dir")
+    gid=$(stat -c%g "$data_dir")
+    if [ $gid -ne 0 ]; then
+        groupmod -g $gid dhcpd
+    fi
+    if [ $uid -ne 0 ]; then
+        usermod -u $uid dhcpd
+    fi
+
+    [ -e "$data_dir/dhcpd.leases" ] || touch "$data_dir/dhcpd.leases"
+    chown dhcpd:dhcpd "$data_dir/dhcpd.leases"
+    if [ -e "$data_dir/dhcpd.leases~" ]; then
+        chown dhcpd:dhcpd "$data_dir/dhcpd.leases~"
+    fi
+
+    container_id=$(grep docker /proc/self/cgroup | sort -n | head -n 1 | cut -d: -f3 | cut -d/ -f3)
+    if perl -e '($id,$name)=@ARGV;$short=substr $id,0,length $name;exit 1 if $name ne $short;exit 0' $container_id $HOSTNAME; then
+        echo "You must add the 'docker run' option '--net=host' if you want to provide DHCP service to the host network."
+    fi
+
+    exec $init -- /usr/sbin/dhcpd -4 -f -d --no-pid -cf "$data_dir/dhcpd.conf" -lf "$data_dir/dhcpd.leases" $IFACE
+else
+    # Run another binary
+    exec $init -- "$@"
+fi