feat(contrib/coreos/user-data): create Deis motd

With the upgrade to CoreOS 310.0.0 in #911, the CoreOS motd
lists failed units, 3 of which we expect to be failed (since
we are stopping the reboot manager service). It probably
makes sense for us to manage our own MOTD anyway, with Deis
support information.

This commit works for both CoreOS 298.0.0 and CoreOS 310.0.0.

Author: carmstrong

contrib/coreos/user-data

@@ -66,3 +66,17 @@ coreos:
       Type=oneshot
       ExecStart=/usr/bin/systemctl stop update-engine.service
       ExecStartPost=/usr/bin/systemctl mask update-engine.service
+  - name: write-deis-motd.service
+    command: start
+    content: |
+      [Unit]
+      Description=write the Deis motd
+      ConditionFileNotEmpty=/run/deis/motd
+
+      [Service]
+      Type=oneshot
+      ExecStartPre=/usr/bin/rm /etc/motd
+      ExecStart=/usr/bin/ln -s /run/deis/motd /etc/motd
+write_files:
+  - path: /run/deis/motd
+    content: " \e[31m* *    \e[34m*   \e[32m*****    \e[39mddddd   eeeeeee iiiiiii   ssss\n\e[31m*   *  \e[34m* *  \e[32m*   *     \e[39md   d   e    e    i     s    s\n \e[31m* *  \e[34m***** \e[32m*****     \e[39md    d  e         i    s\n\e[32m*****  \e[31m* \e[34m*    *       \e[39md     d e         i     s\n\e[32m*   * \e[31m*   *  \e[34m* *      \e[39md     d eee       i      sss\n\e[32m*****  \e[31m* *  \e[34m*****     \e[39md     d e         i         s\n  \e[34m*   \e[32m*****  \e[31m* *      \e[39md    d  e         i          s\n \e[34m* *  \e[32m*   * \e[31m*   *     \e[39md   d   e    e    i    s    s\n\e[34m***** \e[32m*****  \e[31m* *     \e[39mddddd   eeeeeee iiiiiii  ssss\n\n\e[39mWelcome to Deis!\n"