check for existing kernel module built by dkms

From: Michael Prokop <mprokop@sipwise.com>

deployment.sh

@@ -938,18 +938,22 @@ EOT
 
   # we require those packages for dkms, so do NOT remove them:
   # binutils cpp-4.3 gcc-4.3-base linux-kbuild-2.6.32
-  if chroot $TARGET dkms status | grep ngcp-mediaproxy-ng ; then
-    # brrrr, don't tell this anyone or i'll commit with http://whatthecommit.com/ as commit msg!
-    KERNELHEADERS=$(basename $(ls -d ${TARGET}/usr/src/linux-headers*amd64 | sort -u | head -1))
-    if [ -z "$KERNELHEADERS" ] ; then
-       echo "Error: no kernel headers found for building the ngcp-mediaproxy-ng kernel module." >&2
-       exit 1
+  if chroot $TARGET dkms status | grep -q ngcp-mediaproxy-ng ; then
+    if chroot $TARGET dkms status | grep -q '^ngcp-mediaproxy-ng.*: installed' ; then
+      echo "ngcp-mediaproxy-ng. kernel package already installed, skipping"
+    else
+      # brrrr, don't tell this anyone or i'll commit with http://whatthecommit.com/ as commit msg!
+      KERNELHEADERS=$(basename $(ls -d ${TARGET}/usr/src/linux-headers*amd64 | sort -u | head -1))
+      if [ -z "$KERNELHEADERS" ] ; then
+         echo "Error: no kernel headers found for building the ngcp-mediaproxy-ng kernel module." >&2
+         exit 1
+      fi
+      KERNELVERSION=${KERNELHEADERS##linux-headers-}
+      NGCPVERSION=$(chroot $TARGET dkms status | grep ngcp-mediaproxy-ng | awk -F, '{print $2}' | sed 's/:.*//')
+      chroot $TARGET dkms build -k $KERNELVERSION --kernelsourcedir /usr/src/$KERNELHEADERS \
+             -m ngcp-mediaproxy-ng -v $NGCPVERSION
+      chroot $TARGET dkms install -k $KERNELVERSION -m ngcp-mediaproxy-ng -v $NGCPVERSION
     fi
-    KERNELVERSION=${KERNELHEADERS##linux-headers-}
-    NGCPVERSION=$(chroot $TARGET dkms status | grep ngcp-mediaproxy-ng | awk -F, '{print $2}' | sed 's/:.*//')
-    chroot $TARGET dkms build -k $KERNELVERSION --kernelsourcedir /usr/src/$KERNELHEADERS \
-           -m ngcp-mediaproxy-ng -v $NGCPVERSION
-    chroot $TARGET dkms install -k $KERNELVERSION -m ngcp-mediaproxy-ng -v $NGCPVERSION
   fi
 
   # make sure all services are stopped