path: root/src/Propellor/Property/Chroot.hs
diff options
authorJoey Hess2017-03-11 16:08:53 -0400
committerJoey Hess2017-03-11 16:08:53 -0400
commit8a7efe723e4de97065424d1e2396fe0ce5144f56 (patch)
tree8f578241c3d5e0c32c96793c71fb162b765875e4 /src/Propellor/Property/Chroot.hs
parentb86dc506337021c84fe836aed3fcaf1a643cc462 (diff)
Implemented hostChroot
As originally seen in my slides at Linux.Conf.Au 2017 in January. Now that it's not vaporware, it allows one Host to build a disk image that has all the properties of another Host. It was easier than I thought to implement this! As expected, Info propagation was slightly tricky. Also, I originally had a lot of machinery to try to use Info to detect infinitely nested chroot loops. But, my machinery didn't work, and when I tested it, ghc did a much better job, causing a "warning: <<loop>>" message to be output instead of such a property using infinite disk space. This commit was sponsored by Bruno BEAUFILS on Patreon.
Diffstat (limited to 'src/Propellor/Property/Chroot.hs')
1 files changed, 21 insertions, 0 deletions
diff --git a/src/Propellor/Property/Chroot.hs b/src/Propellor/Property/Chroot.hs
index 9624a0f3..4b9b48e1 100644
--- a/src/Propellor/Property/Chroot.hs
+++ b/src/Propellor/Property/Chroot.hs
@@ -1,9 +1,11 @@
{-# LANGUAGE FlexibleContexts, GADTs, DeriveDataTypeable #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
module Propellor.Property.Chroot (
+ hostChroot,
@@ -290,3 +292,22 @@ setInChroot h = h { hostInfo = hostInfo h `addInfo` InfoVal (InChroot True) }
newtype InChroot = InChroot Bool
deriving (Typeable, Show)
+-- | Generates a Chroot that has all the properties of a Host.
+-- Note that it's possible to create loops using this, where a host
+-- contains a Chroot containing itself etc. Such loops will be detected at
+-- runtime.
+hostChroot :: ChrootBootstrapper bootstrapper => Host -> bootstrapper -> FilePath -> Chroot
+hostChroot h bootstrapper d = chroot
+ where
+ chroot = Chroot d bootstrapper pinfo h
+ pinfo = propagateHostChrootInfo h chroot
+-- This is different than propagateChrootInfo in that Info using
+-- HostContext is not made to use the name of the chroot as its context,
+-- but instead uses the hostname of the Host.
+propagateHostChrootInfo :: Host -> Chroot -> InfoPropagator
+propagateHostChrootInfo h c p =
+ propagateContainer (hostName h) c $
+ p `setInfoProperty` chrootInfo c