Add Gentoo to the dhcp-all-interfaces element

This makes use of the dhcpcd package and it's ability to run on all
interfaces by default.  We disable the privacy extensions and dhcp
overriding the hostname (both are enabled by default).  Other than
that it 'just works' and was the method used to bring up interfaces
on Gentoo Openstack images before we switched to building with DIB.

Change-Id: I02c14927d70b22f560c6fc149fefca0f93933f56

elements/dhcp-all-interfaces/README.rst

@@ -9,6 +9,11 @@ to know ahead of time which one is which, so we will simply run a
 DHCP client on all interfaces with real MAC addresses (except lo) that
 are visible on the first boot.
 
-The script /usr/local/sbin/dhcp-all-interfaces.sh will be called
+On non-Gentoo based distributions the script
-early in each boot and will scan available network interfaces and
+/usr/local/sbin/dhcp-all-interfaces.sh will be called early in each
-ensure they are configured properly before networking services are started.
+boot and will scan available network interfaces and ensure they are
+configured properly before networking services are started.
+
+On Gentoo based distributions we will install the dhcpcd package and
+ensure the service starts at boot.  This service automatically sets
+up all interfaces found via dhcp and/or dhcpv6 (or SLAAC).

elements/dhcp-all-interfaces/element-deps

@@ -0,0 +1,2 @@
+package-installs
+pkg-map

elements/dhcp-all-interfaces/install.d/50-dhcp-all-interfaces

@@ -8,7 +8,10 @@ set -o pipefail
 
 SCRIPTDIR=$(dirname $0)
 
+# this script is not needed on Gentoo.
+if [ "$DISTRO_NAME" != "gentoo" ]; then
     install -D -g root -o root -m 0755 ${SCRIPTDIR}/dhcp-all-interfaces.sh /usr/local/sbin/dhcp-all-interfaces.sh
+fi
 
 DIB_INIT_SYSTEM=$(dib-init-system)
 if [ "$DIB_INIT_SYSTEM" == "upstart" ]; then
@@ -19,4 +22,10 @@ elif [ "$DIB_INIT_SYSTEM" == "systemd" ]; then
 elif [ "$DIB_INIT_SYSTEM" == "sysv" ]; then
     install -D -g root -o root -m 0755 ${SCRIPTDIR}/dhcp-all-interfaces.init /etc/init.d/dhcp-all-interfaces
     update-rc.d dhcp-all-interfaces defaults
+elif [ "$DISTRO_NAME" == "gentoo" ]; then
+    # let ipv6 use normal slaac
+    sed -i 's/slaac/#slaac/g' /etc/dhcpcd.conf
+    # don't let dhcpcd set domain name or hostname
+    sed -i 's/domain_name\,\ domain_search\,\ host_name/domain_search/g' /etc/dhcpcd.conf
+    rc-update add dhcpcd default
 fi

elements/dhcp-all-interfaces/install.d/60-remove-cloud-image-interfaces

@@ -18,6 +18,9 @@ rm -f /etc/network/interfaces.d/eth0.cfg
 # Debian
 rm -f /etc/network/interfaces.d/eth0
 
+# Gentoo
+rm -f /etc/conf.d/net*
+
 # /etc/network/interfaces distributions
 if [ -f "/etc/network/interfaces" ]; then
     printf "auto lo\niface lo inet loopback\n\n" > /etc/network/interfaces

elements/dhcp-all-interfaces/package-installs.yaml

@@ -0,0 +1 @@
+dhcpcd:

elements/dhcp-all-interfaces/pkg-map

@@ -0,0 +1,10 @@
+{
+  "family": {
+    "gentoo": {
+      "dhcpcd": "net-misc/dhcpcd"
+    }
+  },
+  "default": {
+    "dhcpcd": ""
+  }
+}