feat(coreos-base/oem-gce): add the gce-add-metadata-host service

One of the requirements of GCE is setting up the metadata host. Do this.

sdk_container/src/third_party/coreos-overlay/coreos-base/oem-gce/files/cloud-config.yml

@@ -2,6 +2,15 @@
 
 coreos:
     units:
+      - name: gce-add-metadata-host.service
+        command: start
+        runtime: yes
+        content: |
+          [Unit]
+          Description=Setup metadata in /etc/hosts
+
+          [Service]
+          ExecStart=/usr/share/oem/bin/gce-add-metadata-host
       - name: gce-coreos-cloudinit.service
         command: restart
         runtime: yes

sdk_container/src/third_party/coreos-overlay/coreos-base/oem-gce/files/gce-add-metadata-host

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+entry="169.254.169.254 metadata"
+
+grep -q "${entry}" /etc/hosts
+
+if [ $? -ne 0 ]; then
+	echo ${entry} >> /etc/hosts
+fi

sdk_container/src/third_party/coreos-overlay/coreos-base/oem-gce/oem-gce-0.0.2-r2.ebuild

@@ -25,6 +25,7 @@ src_install() {
 	dobin ${FILESDIR}/gce-ssh-key
 	dobin ${FILESDIR}/gce-coreos-cloudinit
 	dobin ${FILESDIR}/gce-setup-environment
+	dobin ${FILESDIR}/gce-add-metadata-host
 
 	insinto "/usr/share/oem"
 	doins ${FILESDIR}/cloud-config.yml