Drop btrfs progs

container/container.go

@@ -136,10 +136,8 @@ func (c *Container) Execute(args string, stdin io.Reader) error {
 	}
 
 	// we want to be sure to remove the /stacker from the generated
-	// filesystem after execution. TODO: parameterize this by storage
-	// backend? it will always be "rootfs" for btrfs and "overlay" for the
-	// overlay backend. Maybe this shouldn't even live here.
-	defer os.Remove(path.Join(c.sc.RootFSDir, c.c.Name(), "rootfs", "stacker"))
+	// filesystem after execution. we should probably parameterize this in
+	// the storage API.
 	defer os.Remove(path.Join(c.sc.RootFSDir, c.c.Name(), "overlay", "stacker"))
 
 	cmd, cleanup, err := embed_exec.GetCommand(

doc/install.md

@@ -36,7 +36,7 @@ packages:
 
 To run `make check` you will also need:
 
-    sudo apt install bats btrfs-progs jq libbtrfs-dev tree
+    sudo apt install bats jq tree
 
 umoci - https://github.com/opencontainers/umoci
 squashtool - https://github.com/project-stacker/squashfs
@@ -53,7 +53,6 @@ The other build dependencies can be satisfied with the following command and
 packages:
 
     sudo dnf install lxc-devel libcap-devel libacl-devel gpgme-devel
-    sudo dnf install btrfs-progs
     sudo dnf install bats jq
 
 ### Building the Stacker Binary

doc/running.md

@@ -55,12 +55,3 @@ released in 5.11.
 Stacker has checks to ensure that it can run with all these environment
 requirements, and will fail fast if it can't do something it should be able to
 do.
-
-#### Importing squashfs images
-
-In order to correctly import squashfs-based images using the btrfs backend,
-[squashtool](https://github.com/project-stacker/squashfs) is also required in `$PATH`. This
-is required because tools like unsquashfs don't understand OCI style whiteouts,
-and so will not extract them correctly. (One could fix this by implementing a
-subsequent extrat pass to fix up overlay style whiteouts, but it would be
-better to just use the overlay backend in this case.)

squashfs/squashfs.go

@@ -13,7 +13,6 @@ import (
 	"sync"
 
 	"github.com/pkg/errors"
-	"golang.org/x/sys/unix"
 )
 
 var checkZstdSupported sync.Once
@@ -168,16 +167,10 @@ func ExtractSingleSquash(squashFile string, extractDir string, storageType strin
 	}
 
 	var uCmd []string
-	if storageType == "btrfs" {
-		if which("squashtool") == "" {
-			return errors.Errorf("must have squashtool (https://github.com/anuvu/squashfs) to correctly extract squashfs using btrfs storage backend")
-		}
-
-		uCmd = []string{"squashtool", "extract", "--whiteouts", "--perms",
-			"--devs", "--sockets", "--owners"}
-		uCmd = append(uCmd, squashFile, extractDir)
-	} else {
+	if storageType == "overlay" {
 		uCmd = []string{"unsquashfs", "-f", "-d", extractDir, squashFile}
+	} else {
+		return errors.Errorf("unknown storage type %v", storageType)
 	}
 
 	cmd := exec.Command(uCmd[0], uCmd[1:]...)
@@ -187,35 +180,6 @@ func ExtractSingleSquash(squashFile string, extractDir string, storageType strin
 	return cmd.Run()
 }
 
-func which(name string) string {
-	return whichSearch(name, strings.Split(os.Getenv("PATH"), ":"))
-}
-
-func whichSearch(name string, paths []string) string {
-	var search []string
-
-	if strings.ContainsRune(name, os.PathSeparator) {
-		if path.IsAbs(name) {
-			search = []string{name}
-		} else {
-			search = []string{"./" + name}
-		}
-	} else {
-		search = []string{}
-		for _, p := range paths {
-			search = append(search, path.Join(p, name))
-		}
-	}
-
-	for _, fPath := range search {
-		if err := unix.Access(fPath, unix.X_OK); err == nil {
-			return fPath
-		}
-	}
-
-	return ""
-}
-
 func mksquashfsSupportsZstd() bool {
 	checkZstdSupported.Do(func() {
 		var stdoutBuffer strings.Builder

test/env.bats

@@ -41,10 +41,6 @@ EOF
     touch roots/.lock .stacker/.lock
     chmod 777 -R roots .stacker
 
-    # this only works in overlay, since the btrfs storage will mount
-    # btrfs.loop and the roots/.lock won't be on the same fs. since the kernel
-    # will give us an EBUSY for mounting the same source to the same target
-    # anyway, that can't race, so it's fine to ignore.
     (
         flock 9
         bad_stacker build