From e49af37fe830fda6fa5f62b7ecaf8e79b45de470 Mon Sep 17 00:00:00 2001 From: Joey Hess Date: Sun, 19 Apr 2015 12:28:08 -0400 Subject: comment --- ...ent_1_c02e8783b91c3c0326bf1b317be4694f._comment | 59 ++++++++++++++++++++++ 1 file changed, 59 insertions(+) create mode 100644 doc/todo/Wishlist:_User.hasLoginShell/comment_1_c02e8783b91c3c0326bf1b317be4694f._comment (limited to 'doc/todo') diff --git a/doc/todo/Wishlist:_User.hasLoginShell/comment_1_c02e8783b91c3c0326bf1b317be4694f._comment b/doc/todo/Wishlist:_User.hasLoginShell/comment_1_c02e8783b91c3c0326bf1b317be4694f._comment new file mode 100644 index 00000000..52043406 --- /dev/null +++ b/doc/todo/Wishlist:_User.hasLoginShell/comment_1_c02e8783b91c3c0326bf1b317be4694f._comment @@ -0,0 +1,59 @@ +[[!comment format=mdwn + username="joey" + subject="""comment 1""" + date="2015-04-19T16:07:24Z" + content=""" +Propellor makes it very easy to put together a property like this. + +Let's start with a property that combines the two properties you mentioned: + + hasLoginShell :: UserName -> FilePath -> Property + hasLoginShell user shell = shellSetTo user shell `requires` shellEnabled shell + +The shellEnabled property can be easily written using propellor's file +manipulation properties. + + -- Need to add an import to the top of the source file. + import qualified Propellor.Property.File as File + + shellEnabled :: FilePath -> Property + shellEnabled shell = "/etc/shells" `File.containsLine` shell + +And then, we want to actually change the user's shell. The `chsh(1)` +program can do that, so we can simply tell propellor the command line to +run: + + shellSetTo :: UserName -> FilePath -> Property + shellSetTo user shell = cmdProperty "chsh" ["--shell", shell, user] + +The only remaining problem with this is that shellSetTo runs chsh every +time, and propellor will always display that it's made a change each time +it runs, even when it didn't really do much. Now, there's an easy way to +avoid that problem, we could just tell propellor that it's a trivial +property, and then it will run chsh every time and not think it made any +change: + + shellSetTo :: UserName -> FilePath -> Property + shellSetTo user shell = trivial $ + cmdProperty "chsh" ["--shell", shell, user] + +But, it's not much harder to do this right. Let's make the property +check if the user's shell is already set to the desired value and avoid +doing anything in that case. + + shellSetTo :: UserName -> FilePath -> Property + shellSetTo user shell = check needchangeshell $ + cmdProperty "chsh" ["--shell", shell, user] + where + needchangeshell = do + currshell <- userShell <$> getUserEntryForName user + return (currshell /= shell) + +And that will probably all work, although I've not tested it. You might +want to throw in some uses of `describe` to give the new properties +more useful descriptions. + +I hope this has been helpful as an explanation of how to add properties to +Propellor, and if you get these properties to work, a patch adding them +to Propellor.User would be happily merged. +"""]] -- cgit v1.2.3