Merge lp:~gary/ubuntu/precise/lxc/bug-951150 into lp:ubuntu/precise/lxc

[Gary Poster]

In lxc-start-ephemeral, convert all bind mounted directories in the ephemeral's fstab to also be ephemeral. This means that, in the common case, all of the instance will be ephemeral.

-b continues to bind mount a directory directly, so it can be used to provide a location to persistently store results if desired. Its implementation has been changed to also use fstab, which simplifies cleanup and is arguably more robust in some circumstances.

Thank you

[Gary Poster (gary)]

Also, "sudo lxc-wait -n $LXC_NAME -s RUNNING" moved down into the lxc-console code path. lxc-wait cannot be run in parallel (bug 951181) so it is problematic. It is only necessary for the lxc-console path, so we moved it there, removing the problem from the "-- [COMMAND [ARGS...]]" path.

[lp:~gary/ubuntu/precise/lxc/bug-951150]

79. By Gary Poster on 2012-03-12

use a true tempfs instead of an overlayfs for the upper ephemeral dir

=== modified file 'debian/changelog'
--- debian/changelog	2012-03-08 21:23:56 +0000
+++ debian/changelog	2012-03-12 14:06:22 +0000
@@ -1,3 +1,11 @@
+lxc (0.7.5-3ubuntu35) precise; urgency=low
+
+  * lxc-start-ephemeral: make fstab bind mounts also ephemeral; simplify
+    the implementation of the (non-ephemeral) -b bind option by using
+    fstab. (LP: #951150)
+
+ -- Gary Poster (Gerbrand Poster IV) <[e-mail]>  Mon, 12 Mar 2012 09:52:24 -0400
+
 lxc (0.7.5-3ubuntu34) precise; urgency=low
 
   [Benji York]

=== modified file 'debian/local/lxc-start-ephemeral'
--- debian/local/lxc-start-ephemeral	2012-03-08 21:23:43 +0000
+++ debian/local/lxc-start-ephemeral	2012-03-12 14:06:22 +0000
@@ -31,16 +31,12 @@
 longoptions='help,orig:,bdir:,user:,ssh-key:'
 
 LXC_RUNNING=0
-LXC_BIND_MOUNTED=0
 LXC_MOUNTED=0
 
 cleanup() {
     if [ $LXC_RUNNING -eq 1 ]; then
         sudo lxc-stop -n $LXC_NAME
     fi
-    if [ $LXC_BIND_MOUNTED -eq 1 ]; then
-        sudo umount $LXC_DIR/rootfs$LXC_BIND
-    fi
     if [ $LXC_MOUNTED -eq 1 ]; then
         sudo umount $LXC_DIR
         sudo umount $OVERLAY_DIR
@@ -50,7 +46,7 @@
     exit 1
 }
 
-trap cleanup SIGTERM SIGINT SIGQUIT 
+trap cleanup SIGTERM SIGINT SIGQUIT
 
 getopt=$(getopt -o $shortoptions --longoptions  $longoptions -- "$@")
 if [ $? != 0 ]; then
@@ -118,27 +114,57 @@
 LXC_NAME=`basename $LXC_DIR`
 sudo mount -t overlayfs -oupperdir=$OVERLAY_DIR,lowerdir=/var/lib/lxc/$LXC_BASE none $LXC_DIR
 LXC_MOUNTED=1
+
+# Update the ephemeral lxc's configuration to reflect the new container name.
+sudo sed -i -e "s/$LXC_BASE/$LXC_NAME/" $LXC_DIR/fstab $LXC_DIR/config $LXC_DIR/rootfs/etc/hostname $LXC_DIR/rootfs/etc/hosts
+
+# Update the fstab to have all bind mounts be ephemeral.
+sudo mv $LXC_DIR/fstab $LXC_DIR/fstab.old
+while read line; do
+    # Pull out the second field of the current line of fstab info
+    path=`echo -n $line | awk '{print $2}'`
+    # If LXC_BIND is not set, or the mount destination of this line is not
+    # LXC_BIND...
+    if [ -z "$LXC_BIND" -o "`readlink -f $path`" != "`readlink -f $LXC_DIR/rootfs$LXC_BIND`" ];
+        then
+        # ...then we should write some form of this line.
+        # If this line is a bind...
+        if [ `echo -n $line | awk '{print $4}'` == "bind" ]; then
+            # ...we should rewrite it as an overlay.
+            source=`echo -n $line | awk '{print $1}'`
+            upperdir=$LXC_DIR/ephemeralbind$source
+            sudo mkdir -p $upperdir
+            sudo chown `sudo stat -c '%U.%G' $source` $upperdir
+            echo "none	$path	overlayfs upperdir=$upperdir,lowerdir=$source 0 0";
+        else
+            # Otherwise, we can pass it through unchanged.
+            echo $line;
+        fi
+    fi
+done < $LXC_DIR/fstab.old > $LXC_DIR/fstab
+sudo rm -f $LXC_DIR/fstab.old
+
+# If LXC_BIND is defined, add it to fstab.
 if [ -n "$LXC_BIND" ]; then
     sudo mkdir -p $LXC_DIR/rootfs$LXC_BIND
-    sudo mount --bind $LXC_BIND $LXC_DIR/rootfs$LXC_BIND
-    LXC_BIND_MOUNTED=1
+    echo "$LXC_BIND	$LXC_DIR/rootfs$LXC_BIND	none bind 0 0" >> $LXC_DIR/fstab
 fi
-sudo sed -i -e "s/$LXC_BASE/$LXC_NAME/" $LXC_DIR/fstab $LXC_DIR/config $LXC_DIR/rootfs/etc/hostname $LXC_DIR/rootfs/etc/hosts
 
 # update the ephemeral container's MAC address (lifted from lxc-clone)
 c=$LXC_DIR/config
 # change hwaddrs
-mv ${c} ${c}.old
+sudo mv ${c} ${c}.old
 (
 while read line; do
-        if [ "${line:0:18}" = "lxc.network.hwaddr" ]; then
-                echo "lxc.network.hwaddr= 00:16:3e:$(openssl rand -hex 3| sed 's/\(..\)/\1:/g; s/.$//')"
-        else
-                echo $line
-        fi
+    if [ "${line:0:18}" = "lxc.network.hwaddr" ]; then
+        hwaddr=$(sudo openssl rand -hex 3| sed 's/\(..\)/\1:/g; s/.$//')
+        echo "lxc.network.hwaddr=00:16:3e:$hwaddr"
+    else
+        echo $line
+    fi
 done
 ) < ${c}.old > ${c}
-rm -f ${c}.old
+sudo rm -f ${c}.old
 
 # precise is now the worst - its dhclient *uses*
 # /var/lib/dhcp3/dhclient.eth0.leases but ships without that
@@ -153,7 +179,6 @@
 echo "Starting up the container..."
 sudo lxc-start -n $LXC_NAME -d
 LXC_RUNNING=1
-sudo lxc-wait -n $LXC_NAME -s RUNNING
 
 if [ $# -gt 0 ]; then
 	# when lxc-attach support arrives in the kernel, we can switch to
@@ -190,6 +215,7 @@
 	    cat $LEASES2 >&2
 	fi
 else
+	sudo lxc-wait -n $LXC_NAME -s RUNNING
 	echo "$LXC_NAME is running"
 	echo "You connect with the command:"
 	echo "    sudo lxc-console -n $LXC_NAME"
@@ -199,10 +225,6 @@
 echo "Stopping lxc" >&2
 sudo lxc-stop -n $LXC_NAME
 sleep 2
-if [ -n "$LXC_BIND" ]; then
-    echo "umounting bind" >&2
-    sudo umount $LXC_DIR/rootfs$LXC_BIND
-fi
 # echo "umounting lxc_dir $LXC_DIR" >&2
 sudo umount $LXC_DIR
 # echo "umounting overlay" >&2