Don't duplicate GRUB_TIMEOUT= in /etc/default/grub

Previously the `GRUB_TIMEOUT` parameter in `/etc/default/grub` was set
at the end of the file.  This superseded the previous definition of
`GRUB_TIMEOUT=5` at the top of the file, but the resulting duplication
was potentially confusing for the user.

This uses a newly added helper method to update the timeout instead.

When possible, the new method updates the original definitions within the
defaults file instead (at the same location within the file as the
original definition, or after commented-out example lines).

1 files changed, 24 insertions, 3 deletions

diff --git a/vmdb/plugins/grub_plugin.py b/vmdb/plugins/grub_plugin.py
index 59b8d8a..cf40e2d 100644
--- a/vmdb/plugins/grub_plugin.py
+++ b/vmdb/plugins/grub_plugin.py
@@ -378,6 +378,29 @@ class GrubStepRunner(vmdb.StepRunnerInterface):
         with open(filename, "w") as f:
             f.write("\n".join(lines) + "\n")
 
+    def set_grub_default(self, chroot, param, value):
+        filename = self.chroot_path(chroot, "/etc/default/grub")
+        newdefault = param + "=" + str(value) + "\n"
+
+        found_param = False
+        newcontents = ""
+        with open(filename, "r+") as f:
+            for line in f:
+                if line.startswith(param + "=") and not found_param:
+                    newcontents += newdefault
+                    found_param = True
+                elif line.startswith("#" + param + "=") and not found_param:
+                    newcontents += line
+                    newcontents += newdefault
+                    found_param = True
+                else:
+                    newcontents += line
+            if found_param:
+                f.seek(0)
+                f.write(newcontents)
+            else:
+                f.write(newdefault)
+
     def add_grub_serial_console(self, chroot):
         filename = self.chroot_path(chroot, "/etc/default/grub")
 
@@ -394,6 +417,4 @@ class GrubStepRunner(vmdb.StepRunnerInterface):
             f.write("GRUB_ENABLE_CRYPTODISK=y\n")
 
     def set_grub_timeout(self, chroot, timeout):
-        filename = self.chroot_path(chroot, "/etc/default/grub")
-        with open(filename, "a") as f:
-            f.write("GRUB_TIMEOUT={}\n".format(timeout))
+        self.set_grub_default(chroot, "GRUB_TIMEOUT", timeout)