From e1b96860bfac2366592a019734e53d7c45fb941c Mon Sep 17 00:00:00 2001 From: Joey Hess Date: Thu, 17 Apr 2014 19:43:12 -0400 Subject: cron locking --- Propellor/Property/Cron.hs | 16 ++++++++++++---- debian/changelog | 2 ++ 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/Propellor/Property/Cron.hs b/Propellor/Property/Cron.hs index 2fa9c87e..d8c072eb 100644 --- a/Propellor/Property/Cron.hs +++ b/Propellor/Property/Cron.hs @@ -3,14 +3,19 @@ module Propellor.Property.Cron where import Propellor import qualified Propellor.Property.File as File import qualified Propellor.Property.Apt as Apt +import Utility.SafeCommand import Data.Char type CronTimes = String --- | Installs a cron job, run as a specificed user, in a particular ---directory. Note that the Desc must be unique, as it is used for the ---cron.d/ filename. +-- | Installs a cron job, run as a specified user, in a particular +-- directory. Note that the Desc must be unique, as it is used for the +-- cron.d/ filename. +-- +-- Only one instance of the cron job is allowed to run at a time, no matter +-- how long it runs. This is accomplished using flock locking of the cron +-- job file. job :: Desc -> CronTimes -> UserName -> FilePath -> String -> Property job desc times user cddir command = cronjobfile `File.hasContent` [ "# Generated by propellor" @@ -18,11 +23,14 @@ job desc times user cddir command = cronjobfile `File.hasContent` , "SHELL=/bin/sh" , "PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin" , "" - , times ++ "\t" ++ user ++ "\t" ++ "cd " ++ cddir ++ " && " ++ command + , times ++ "\t" ++ user ++ "\t" + ++ "flock -n " ++ shellEscape cronjobfile + ++ " -c sh -c " ++ shellEscape cmdline ] `requires` Apt.serviceInstalledRunning "cron" `describe` ("cronned " ++ desc) where + cmdline = "cd " ++ cddir ++ " && " ++ command cronjobfile = "/etc/cron.d/" ++ map sanitize desc sanitize c | isAlphaNum c = c diff --git a/debian/changelog b/debian/changelog index 172ca7ae..e7654a07 100644 --- a/debian/changelog +++ b/debian/changelog @@ -8,6 +8,8 @@ propellor (0.3.1) UNRELEASED; urgency=medium * Properties can now be satisfied differently on different operating systems. * Standard apt configuration for stable now includes backports. + * Cron jobs generated by propellor use flock(1) to avoid multiple + instances running at a time. -- Joey Hess Fri, 11 Apr 2014 15:00:11 -0400 -- cgit v1.2.3