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|
module Propellor.Property.Systemd (
installed,
started,
stopped,
enabled,
disabled,
persistentJournal,
Container,
container,
nspawned,
) where
import Propellor
import qualified Propellor.Property.Chroot as Chroot
import qualified Propellor.Property.Apt as Apt
import qualified Propellor.Property.File as File
import Utility.SafeCommand
import Utility.FileMode
import Data.List.Utils
type ServiceName = String
type MachineName = String
data Container = Container MachineName Chroot.Chroot Host
instance Hostlike Container where
(Container n c h) & p = Container n c (h & p)
(Container n c h) &^ p = Container n c (h &^ p)
getHost (Container _ _ h) = h
-- dbus is only a Recommends of systemd, but is needed for communication
-- from the systemd inside a container to the one outside, so make sure it
-- gets installed.
installed :: Property
installed = Apt.installed ["systemd", "dbus"]
-- | Starts a systemd service.
started :: ServiceName -> Property
started n = trivial $ cmdProperty "systemctl" ["start", n]
`describe` ("service " ++ n ++ " started")
-- | Stops a systemd service.
stopped :: ServiceName -> Property
stopped n = trivial $ cmdProperty "systemctl" ["stop", n]
`describe` ("service " ++ n ++ " stopped")
-- | Enables a systemd service.
enabled :: ServiceName -> Property
enabled n = trivial $ cmdProperty "systemctl" ["enable", n]
`describe` ("service " ++ n ++ " enabled")
-- | Disables a systemd service.
disabled :: ServiceName -> Property
disabled n = trivial $ cmdProperty "systemctl" ["disable", n]
`describe` ("service " ++ n ++ " disabled")
-- | Enables persistent storage of the journal.
persistentJournal :: Property
persistentJournal = check (not <$> doesDirectoryExist dir) $
combineProperties "persistent systemd journal"
[ cmdProperty "install" ["-d", "-g", "systemd-journal", dir]
, cmdProperty "setfacl" ["-R", "-nm", "g:adm:rx,d:g:adm:rx", dir]
, started "systemd-journal-flush"
]
`requires` Apt.installed ["acl"]
where
dir = "/var/log/journal"
-- | Defines a container with a given machine name.
--
-- Properties can be added to configure the Container.
--
-- > container "webserver" (Chroot.debootstrapped (System (Debian Unstable) "amd64") mempty)
-- > & Apt.installedRunning "apache2"
-- > & ...
container :: MachineName -> (FilePath -> Chroot.Chroot) -> Container
container name mkchroot = Container name c h
& os system
where
c@(Chroot.Chroot _ system _ _) = mkchroot (containerDir name)
h = Host name [] mempty
-- | Runs a container using systemd-nspawn.
--
-- A systemd unit is set up for the container, so it will automatically
-- be started on boot.
--
-- Systemd is automatically installed inside the container, and will
-- communicate with the host's systemd. This allows systemctl to be used to
-- examine the status of services running inside the container.
--
-- When the host system has persistentJournal enabled, journactl can be
-- used to examine logs forwarded from the container.
--
-- Reverting this property stops the container, removes the systemd unit,
-- and deletes the chroot and all its contents.
nspawned :: Container -> RevertableProperty
nspawned c@(Container name (Chroot.Chroot loc system builderconf _) h) =
RevertableProperty setup teardown
where
setup = combineProperties ("nspawned " ++ name) $
map toProp steps ++ [containerprovisioned]
teardown = combineProperties ("not nspawned " ++ name) $
map (toProp . revert) (reverse steps)
steps =
[ enterScript c
, chrootprovisioned
, nspawnService c
]
-- When provisioning the chroot, pass a version of the Host
-- that only has the Property of systemd being installed.
-- This is to avoid starting any daemons in the chroot,
-- which would not run in the container's namespace.
chrootprovisioned = Chroot.provisioned' (Chroot.propigateChrootInfo chroot) $
mkChroot $ h { hostProperties = [installed] }
-- Use nsenter to enter container and and run propellor to
-- finish provisioning.
containerprovisioned = Chroot.propellChroot chroot
(enterContainerProcess c)
mkChroot = Chroot.Chroot loc system builderconf
chroot = mkChroot h
nspawnService :: Container -> RevertableProperty
nspawnService (Container name _ _) = RevertableProperty setup teardown
where
service = nspawnServiceName name
servicefile = "/etc/systemd/system/multi-user.target.wants" </> service
setup = check (not <$> doesFileExist servicefile) $
started service
`requires` enabled service
teardown = check (doesFileExist servicefile) $
disabled service
`requires` stopped service
-- | Installs a "enter-machinename" script that root can use to run a
-- command inside the container.
--
-- This uses nsenter to enter the container, by looking up the pid of the
-- container's init process and using its namespace.
enterScript :: Container -> RevertableProperty
enterScript c@(Container name _ _) = RevertableProperty setup teardown
where
setup = combineProperties ("generated " ++ enterScriptFile c)
[ scriptfile `File.hasContent`
[ "#!/bin/sh"
, "# Generated by propellor"
, "pid=\"$(machinectl show " ++ shellEscape name ++ " -p Leader | cut -d= -f2)\" || true"
, "if [ -n \"$pid\" ]; then"
, "\tnsenter -p -u -n -i -m -t \"$pid\" \"$@\""
, "else"
, "\techo container not running >&2"
, "\texit 1"
, "fi"
]
, scriptfile `File.mode` combineModes (readModes ++ executeModes)
]
teardown = File.notPresent scriptfile
scriptfile = enterScriptFile c
enterScriptFile :: Container -> FilePath
enterScriptFile (Container name _ _ ) = "/usr/local/bin/enter-" ++ mungename name
enterContainerProcess :: Container -> [String] -> CreateProcess
enterContainerProcess = proc . enterScriptFile
nspawnServiceName :: MachineName -> ServiceName
nspawnServiceName name = "systemd-nspawn@" ++ name ++ ".service"
containerDir :: MachineName -> FilePath
containerDir name = "/var/lib/container" </> mungename name
mungename :: MachineName -> String
mungename = replace "/" "_"
|
