Add distbuild-trove-nfsboot.write

The nfsboot.write deployment extension has been deprecated for a while
because it's not generally useful. It's only used for deploying
distbuild nodes to a Trove, as far as I know.

We still need to support setting up a bunch of machines that boot over
NFS from a Trove. But we can do this in a special-purpose .write
extension.

The new distbuild-trove-nfsboot.write is much more efficient than
the more generic nfsboot.write: instead of treating each system
individually (thus copying an almost identical ~2GB rootfs to the Trove
once per node) it copies the system image to the Trove once, and /then/
sets up a rootfs per node.

Upgrades are now supported, although the code assumes distbuild nodes
are stateless (as they should be) so nothing special is done for
upgrades, other than checking that there is already a version of the
given system in existance. The new extension does not create an
orig/ and run/ version of each system, because there is no need when the
deployed system is stateless.

There could be further gains in efficiency, but I don't have time to do
them right now. This write extension is full of compromises, its goal is
to better support the existing users who have a Trove and a distbuild
network deployed via NFS. It is specifically not intended to be useful
for other purposes.

Change-Id: I9a50c58b714ed272212d1d6c55b289aaa96051b1

1 files changed, 49 insertions, 0 deletions

diff --git a/distbuild-trove-nfsboot.help b/distbuild-trove-nfsboot.help
new file mode 100644
index 00000000..62f1455c
--- /dev/null
+++ b/distbuild-trove-nfsboot.help
@@ -0,0 +1,49 @@
+# Copyright (C) 2014, 2015 Codethink Limited
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, see <http://www.gnu.org/licenses/>.
+
+help: |
+    Deploy a distbuild network, using a Trove to serve the kernel and rootfs.
+
+    The `location` argument is the hostname of the Trove system.
+
+    The following configuration values must be specified:
+
+      - DISTBUILD_CONTROLLER: hostname of controller system
+      - DISTBUILD_WORKERS: hostnames of each worker system
+      - DISTBUILD_GIT_SERVER: Trove hostname
+      - DISTBUILD_SHARED_ARTIFACT_CACHE: Trove hostname
+      - DISTBUILD_TROVE_ID: Trove ID
+      - DISTBUILD_WORKER_SSH_KEY: SSH key to be used for ssh:// repos
+
+    A note on TROVE_ID: the current distbuild-setup service requires that
+    a single 'Trove ID' is specified. This is used in Morph for expanding
+    keyed URLs. If you set TROVE_ID=foo for example, foo:bar will be expanded
+    to git://$GIT_SERVER/foo, in addition to the standard baserock: and
+    upstream: prefixes that you can use.
+
+    The WORKER_SSH_KEY must be provided, even if you don't need it. The
+    distbuild-setup service could be changed to make it optional.
+
+    The following configuration values are optional:
+
+      - HOST_MAP: a list of key=value pairs mapping hostnames to IP addresses,
+          or fully-qualified domain names. Useful if you
+          cannot rely on hostname resolution working for your deploment.
+
+    The extension will connect to root@location via ssh to copy the kernel and
+    rootfs, and configure the nfs server. It will duplicate the kernel and
+    rootfs once for each node in the distbuild network.
+
+    The deployment mechanism makes assumptions about the bootloader
+    configuration of the target machines.