don't look in host path for thin_ls binary

deploy/Dockerfile

@@ -5,6 +5,7 @@ ENV GLIBC_VERSION "2.23-r3"
 
 RUN apk --no-cache add ca-certificates wget device-mapper && \
     apk --no-cache add zfs --repository http://dl-3.alpinelinux.org/alpine/edge/main/ && \
+    apk --no-cache add thin-provisioning-tools --repository http://dl-3.alpinelinux.org/alpine/edge/testing/ && \
     wget -q -O /etc/apk/keys/sgerrand.rsa.pub https://raw.githubusercontent.com/sgerrand/alpine-pkg-glibc/master/sgerrand.rsa.pub && \
     wget https://github.com/sgerrand/alpine-pkg-glibc/releases/download/${GLIBC_VERSION}/glibc-${GLIBC_VERSION}.apk && \
     wget https://github.com/andyshinn/alpine-pkg-glibc/releases/download/${GLIBC_VERSION}/glibc-bin-${GLIBC_VERSION}.apk && \

devicemapper/util.go

@@ -22,15 +22,11 @@ import (
 // ThinLsBinaryPresent returns the location of the thin_ls binary in the mount
 // namespace cadvisor is running in or an error.  The locations checked are:
 //
+// - /sbin/
 // - /bin/
 // - /usr/sbin/
 // - /usr/bin/
 //
-// ThinLsBinaryPresent checks these paths relative to:
-//
-// 1. For non-containerized operation - `/`
-// 2. For containerized operation - `/rootfs`
-//
 // The thin_ls binary is provided by the device-mapper-persistent-data
 // package.
 func ThinLsBinaryPresent() (string, error) {
@@ -39,21 +35,14 @@ func ThinLsBinaryPresent() (string, error) {
 		err        error
 	)
 
-	for _, path := range []string{"/bin", "/usr/sbin/", "/usr/bin"} {
+	for _, path := range []string{"/sbin", "/bin", "/usr/sbin/", "/usr/bin"} {
 		// try paths for non-containerized operation
 		// note: thin_ls is most likely a symlink to pdata_tools
 		thinLsPath = filepath.Join(path, "thin_ls")
 		_, err = os.Stat(thinLsPath)
 		if err == nil {
 			return thinLsPath, nil
 		}
-
-		// try paths for containerized operation
-		thinLsPath = filepath.Join("/rootfs", thinLsPath)
-		_, err = os.Stat(thinLsPath)
-		if err == nil {
-			return thinLsPath, nil
-		}
 	}
 
 	return "", fmt.Errorf("unable to find thin_ls binary")