feat!: don't mount code from host directory

Up until now, `restyle` worked by mounting the code directory into the
restyler container and letting the fixes occur against those files
there.

This has always come with some issues:

1. The container may change file ownership to `root`
2. The process may create working or backup files
3. The process needs to know about the host file system in order to
   mount correctly if `restyle` itself is dockerized

(1) was an open issue we've not solved. (2) we solved with a Big Hammer,
running `git clean` at the end. And (3) we had solved with a
`HOST_DIRECTORY` option, but thankfully no longer needed when we moved
to a native `restyle` binary.

Attempting to run on Forgejo actions reintroduces (3) because `restyle`
is again in a container there. Unfortunately we can't (easily) solve it
with `HOST_DIRECTORY` because that path is more volatile and harder to
discover than it was on GitHub Actions. Therefore a new solution was
implemented.

Now, what we do is:

1. Create a docker volume
2. Use a temporary container to fill the volume with the current
   directory's contents
3. Run all restylers with that volume mounted
4. Use a temporary container to copy out the paths we were attempting to
   restyle

This is a bit of complexity, but at least 1, 2, and 4 occur once and not
per restyler. It completely avoids having to have knowledge of the host
file system since the `docker cp` commands work with paths where they
are even if the process it itself containerized.

As a bonus, we avoid the other two other issues:

1. The files are copied out, and so retain correct ownership, instead of
   being modified in a container as `root`
2. Since we aren't mounting the whole directory, but only copying back
   out the files we intended to change, we have no issue with dirtying
   things such that we need or want a `git clean` step

Author: pbrisbin

restyler.cabal

@@ -1,6 +1,6 @@
 cabal-version: 1.12
 
--- This file has been generated from package.yaml by hpack version 0.38.0.
+-- This file has been generated from package.yaml by hpack version 0.38.1.
 --
 -- see: https://github.com/sol/hpack
 
@@ -14,6 +14,7 @@ library
       Restyler.AnnotatedException
       Restyler.App
       Restyler.CLI
+      Restyler.CodeVolume
       Restyler.Config
       Restyler.Config.AutoEnable
       Restyler.Config.CommitTemplate
@@ -22,7 +23,6 @@ library
       Restyler.Config.Exclude
       Restyler.Config.FailOnDifferences
       Restyler.Config.Glob
-      Restyler.Config.HostDirectory
       Restyler.Config.Ignore
       Restyler.Config.Image
       Restyler.Config.ImageCleanup

src/Restyler/App.hs

@@ -61,11 +61,9 @@ instance HasDryRun App where getDryRun = (.config.dryRun)
 instance HasEnabled App where getEnabled = (.config.enabled)
 instance HasExclude App where getExclude = (.config.exclude)
 instance HasFailOnDifferences App where getFailOnDifferences = (.config.failOnDifferences)
-instance HasHostDirectory App where getHostDirectory = (.config.hostDirectory)
 instance HasIgnores App where getIgnores = (.config.ignores)
 instance HasImageCleanup App where getImageCleanup = (.config.imageCleanup)
 instance HasManifest App where getManifest = (.config.restylersManifest)
-instance HasNoClean App where getNoClean = (.config.noClean)
 instance HasNoCommit App where getNoCommit = (.config.noCommit)
 instance HasNoPull App where getNoPull = (.config.noPull)
 instance HasRemoteFiles App where getRemoteFiles = (.config.remoteFiles)

src/Restyler/CodeVolume.hs

@@ -0,0 +1,48 @@
+-- |
+--
+-- Module      : Restyler.CodeVolume
+-- Copyright   : (c) 2025 Patrick Brisbin
+-- License     : AGPL-3
+-- Maintainer  : pbrisbin@gmail.com
+-- Stability   : experimental
+-- Portability : POSIX
+module Restyler.CodeVolume
+  ( withCodeVolume
+  ) where
+
+import Restyler.Prelude
+
+import Restyler.Monad.Docker
+import UnliftIO.Exception (bracket)
+
+withCodeVolume :: (MonadDocker m, MonadUnliftIO m) => (String -> m a) -> m a
+withCodeVolume = bracket acquire dockerVolumeRm
+ where
+  acquire :: (MonadDocker m, MonadUnliftIO m) => m String
+  acquire = withVolumeInContainer tmpVolumeName $ \cName cPath -> do
+    tmpVolumeName <$ dockerCp "." (cName <> ":" <> cPath)
+
+withVolumeInContainer
+  :: (MonadDocker m, MonadUnliftIO m)
+  => String
+  -> (String -> FilePath -> m a)
+  -> m a
+withVolumeInContainer name = bracket acquire (dockerRm . fst) . uncurry
+ where
+  acquire :: MonadDocker m => m (String, FilePath)
+  acquire = do
+    dockerCreate
+      $ ["--name", tmpContainerName]
+      <> ["--volume", name <> ":" <> tmpContainerPath]
+      <> ["busybox"]
+
+    pure (tmpContainerName, tmpContainerPath)
+
+tmpVolumeName :: String
+tmpVolumeName = "restyler-code-volume"
+
+tmpContainerName :: String
+tmpContainerName = "restyler-tmp-container"
+
+tmpContainerPath :: FilePath
+tmpContainerPath = "/data"

src/Restyler/Config.hs

@@ -29,7 +29,6 @@ import Restyler.Config.Enabled as X
 import Restyler.Config.Exclude as X
 import Restyler.Config.FailOnDifferences as X
 import Restyler.Config.Glob
-import Restyler.Config.HostDirectory as X
 import Restyler.Config.Ignore as X
 import Restyler.Config.ImageCleanup as X
 import Restyler.Config.LogSettings as X
@@ -51,7 +50,6 @@ data Config = Config
   , restylerOverrides :: [RestylerOverride]
   , ignores :: Ignores
   , remoteFiles :: [RemoteFile]
-  , hostDirectory :: Path Abs Dir
   , imageCleanup :: Bool
   , noPull :: Bool
   , restrictions :: Restrictions
@@ -87,7 +85,6 @@ configParser sources =
     exclude <- excludeParser
     ignores <- ignoresParser
     remoteFiles <- remoteFilesParser
-    hostDirectory <- subConfig_ "docker" hostDirectoryParser
     imageCleanup <- subConfig_ "docker" imageCleanupParser
     noPull <- subConfig_ "docker" noPullParser
     restrictions <- subConfig_ "docker" $ subAll "restyler" restrictionsParser

src/Restyler/Config/HostDirectory.hs

@@ -7,24 +7,21 @@
 -- Stability   : experimental
 -- Portability : POSIX
 module Restyler.Config.NoClean
-  ( HasNoClean (..)
-  , noCleanParser
+  ( noCleanParser
   ) where
 
 import Restyler.Prelude
 
 import OptEnvConf
 
-class HasNoClean env where
-  getNoClean :: env -> Bool
-
 noCleanParser :: Parser Bool
 noCleanParser =
   not
     <$> withDefault
       False
       ( yesNoSwitch
-          [ help "Run git-clean after restyling"
+          [ help "Unused"
           , name "clean"
+          , hidden
           ]
       )

src/Restyler/Config/NoClean.hs

@@ -24,9 +24,14 @@ import System.Process.Typed
 
 class Monad m => MonadDocker m where
   dockerPull :: HasCallStack => String -> m ExitCode
+  dockerCreate :: HasCallStack => [String] -> m ()
   dockerRun :: HasCallStack => [String] -> m ExitCode
   dockerRunStdout :: HasCallStack => [String] -> m (ExitCode, Text)
   dockerImageRm :: HasCallStack => String -> m ()
+  dockerVolumeCreate :: HasCallStack => String -> m ()
+  dockerVolumeRm :: HasCallStack => String -> m ()
+  dockerCp :: String -> String -> m ()
+  dockerRm :: String -> m ()
 
 -- | An instance that invokes the real @docker@
 newtype ActualDocker m a = ActualDocker
@@ -47,9 +52,14 @@ instance
   => MonadDocker (ActualDocker m)
   where
   dockerPull image = runDocker ["pull", "--quiet", image]
-  dockerRun args = runDocker $ ["run", "--rm"] <> args
-  dockerRunStdout args = runDockerStdout $ ["run", "--rm"] <> args
+  dockerCreate args = runDocker_ $ ["create", "--quiet"] <> args
+  dockerRun args = runDocker $ ["run"] <> args
+  dockerRunStdout args = runDockerStdout $ ["run"] <> args
   dockerImageRm image = runDocker_ ["image", "rm", "--force", image]
+  dockerVolumeCreate name = runDocker_ ["volume", "create", "--quiet", name]
+  dockerVolumeRm name = runDocker_ ["volume", "rm", name]
+  dockerCp src dst = runDocker_ ["cp", "--quiet", src, dst]
+  dockerRm name = runDocker_ ["rm", name]
 
 runDocker
   :: (HasCallStack, HasLogger env, MonadLogger m, MonadReader env m, MonadUnliftIO m)
@@ -86,6 +96,11 @@ newtype NullDocker m a = NullDocker
 
 instance Monad m => MonadDocker (NullDocker m) where
   dockerPull _ = pure ExitSuccess
+  dockerCreate _ = pure ()
   dockerRun _ = pure ExitSuccess
   dockerRunStdout _ = pure (ExitSuccess, "")
   dockerImageRm _ = pure ()
+  dockerVolumeCreate _ = pure ()
+  dockerVolumeRm _ = pure ()
+  dockerCp _ _ = pure ()
+  dockerRm _ = pure ()

src/Restyler/Monad/Docker.hs

@@ -26,7 +26,6 @@ class Monad m => MonadGit m where
   isGitRepository :: HasCallStack => m Bool
   gitDiffNameOnly :: HasCallStack => Maybe String -> m [FilePath]
   gitCommit :: HasCallStack => String -> NonEmpty FilePath -> m String
-  gitClean :: HasCallStack => m ()
   gitResetHard :: HasCallStack => String -> m ()
 
 -- | An instance that invokes the real @git@
@@ -52,12 +51,6 @@ instance
   gitCommit msg paths = do
     runGit_ $ ["commit", "--message", msg, "--"] <> toList paths
     readGitChomp ["rev-parse", "HEAD"]
-  gitClean = do
-    ec <- runGitExitCode ["clean", "-d", "--force"]
-    when (ec /= ExitSuccess)
-      $ logWarn
-      $ "git clean not successful"
-      :# ["exitCode" .= show @Text ec]
   gitResetHard ref = runGit_ ["reset", "--hard", ref]
 
 runGit_
@@ -131,5 +124,4 @@ instance Monad m => MonadGit (NullGit m) where
   isGitRepository = pure False
   gitDiffNameOnly _ = pure []
   gitCommit _ _ = pure ""
-  gitClean = pure ()
   gitResetHard _ = pure ()

src/Restyler/Monad/Git.hs

@@ -35,12 +35,10 @@ run
      , HasDryRun env
      , HasEnabled env
      , HasExclude env
-     , HasHostDirectory env
      , HasIgnores env
      , HasImageCleanup env
      , HasLabelNames pr
      , HasManifest env
-     , HasNoClean env
      , HasNoCommit env
      , HasNoPull env
      , HasPullRequestState pr
@@ -92,7 +90,4 @@ run pr paths = do
              , "sha" .= result.sha
              ]
 
-      noClean <- asks $ (||) <$> getDryRun <*> getNoClean
-      unless noClean gitClean
-
       pure $ maybe RestyleNoDifference (const RestyleDifference) mresults