fix issue where rootfs path strips to the empty string (#1464)

Change-type: patch
Connects-to: #1463
Signed-off-by: dt-rush <nickp@balena.io>

3 files changed, 7 insertions, 1 deletions

diff --git a/collector/filesystem_linux_test.go b/collector/filesystem_linux_test.go
index 267ad06..6271c19 100644
--- a/collector/filesystem_linux_test.go
+++ b/collector/filesystem_linux_test.go
@@ -120,6 +120,7 @@ func TestPathRootfs(t *testing.T) {
 
         expected := map[string]string{
                 // should modify these mountpoints (removes /host, see fixture proc file)
+                "/":              "",
                 "/media/volume1": "",
                 "/media/volume2": "",
                 // should not modify these mountpoints
diff --git a/collector/fixtures_bindmount/proc/mounts b/collector/fixtures_bindmount/proc/mounts
index 2ef6401..32f9567 100644
--- a/collector/fixtures_bindmount/proc/mounts
+++ b/collector/fixtures_bindmount/proc/mounts
@@ -1,3 +1,4 @@
+/dev/nvme1n0 /host ext4 rw,seclabel,relatime,data=ordered 0 0
 /dev/nvme1n1 /host/media/volume1 ext4 rw,seclabel,relatime,data=ordered 0 0
 /dev/nvme1n2 /host/media/volume2 ext4 rw,seclabel,relatime,data=ordered 0 0
 tmpfs /dev/shm tmpfs rw,nosuid,nodev 0 0
diff --git a/collector/paths.go b/collector/paths.go
index 6150600..5f5a7b4 100644
--- a/collector/paths.go
+++ b/collector/paths.go
@@ -44,5 +44,9 @@ func rootfsStripPrefix(path string) string {
         if *rootfsPath == "/" {
                 return path
         }
-        return strings.TrimPrefix(path, *rootfsPath)
+        stripped := strings.TrimPrefix(path, *rootfsPath)
+        if stripped == "" {
+                return "/"
+        }
+        return stripped
 }