[lxc-devel] [PATCHv3 11/14] refresh lxc-netstat
David Ward
david.ward at ll.mit.edu
Wed Mar 21 23:28:52 UTC 2012
Modify the cgroup search to only use hierarchies that contain one
or more subsystems. When searching, if a hierarchy contains the
'ns' subsystem, do not append '/lxc' to the parent cgroup.
Change method of bind mounting /proc/<pid>/net onto /proc/net, to
avoid error "cannot mount block device /proc/<pid>/net read-only".
Check that user is root. Check that container name is specified
before calling 'exec'.
Update the help information.
Print error messages and help information to stderr.
Make indentation consistent.
Signed-off-by: David Ward <david.ward at ll.mit.edu>
---
src/lxc/lxc-netstat.in | 146 +++++++++++++++++++++++++++++++----------------
1 files changed, 96 insertions(+), 50 deletions(-)
diff --git a/src/lxc/lxc-netstat.in b/src/lxc/lxc-netstat.in
index 9e7eec3..113c0da 100644
--- a/src/lxc/lxc-netstat.in
+++ b/src/lxc/lxc-netstat.in
@@ -1,21 +1,70 @@
#!/bin/bash
-# set -ex
+
+#
+# lxc: linux Container library
+
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# Lesser General Public License for more details.
+
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
usage() {
- echo "usage: $(basename $0) --name <name> [netstat options]"
+ echo "usage: $(basename $0) --name NAME [--] [NETSTAT_OPTIONS...]" >&2
}
help() {
usage
- echo
- echo "execute netstat for the specified container"
- echo "with the added netstat options"
- echo
- echo "Options:"
- echo "name : name of the container"
- echo "help : this current help."
- echo
- echo "to be executed as root."
+ echo >&2
+ echo "Execute 'netstat' for the specified container." >&2
+ echo >&2
+ echo " --name NAME specify the container name" >&2
+ echo " NETSTAT_OPTIONS netstat command options (see \`netstat --help')" >&2
+}
+
+get_parent_cgroup()
+{
+ local hierarchies hierarchy fields subsystems init_cgroup mountpoint
+
+ parent_cgroup=""
+
+ # Obtain a list of hierarchies that contain one or more subsystems
+ hierarchies=$(tail -n +2 /proc/cgroups | cut -f 2)
+
+ # Iterate through the list until a suitable hierarchy is found
+ for hierarchy in $hierarchies; do
+ # Obtain information about the init process in the hierarchy
+ fields=$(grep -E "^$hierarchy:" /proc/1/cgroup | head -n 1)
+ if [ -z "$fields" ]; then continue; fi
+ fields=${fields#*:}
+
+ # Get a comma-separated list of the hierarchy's subsystems
+ subsystems=${fields%:*}
+
+ # Get the cgroup of the init process in the hierarchy
+ init_cgroup=${fields#*:}
+
+ # Get the filesystem mountpoint of the hierarchy
+ mountpoint=$(grep -E "^cgroup [^ ]+ [^ ]+ ([^ ]+,)?$subsystems(,[^ ]+)? " /proc/self/mounts | cut -d ' ' -f 2)
+ if [ -z "$mountpoint" ]; then continue; fi
+
+ # Return the absolute path to the containers' parent cgroup
+ # (do not append '/lxc' if the hierarchy contains the 'ns' subsystem)
+ if [[ ",$subsystems," == *,ns,* ]]; then
+ parent_cgroup="${mountpoint}${init_cgroup%/}"
+ else
+ parent_cgroup="${mountpoint}${init_cgroup%/}/lxc"
+ fi
+ break
+ done
}
exec=""
@@ -25,19 +74,24 @@ if [ $# -eq 0 ]; then
exit 1
fi
-for i in "$@"; do
- case $i in
+while true; do
+ case $1 in
-h|--help)
help; exit 1;;
-n|--name)
name=$2; shift 2;;
--exec)
exec="exec"; shift;;
+ --)
+ shift; break;;
+ *)
+ break;
esac
done
-if [ -z "$exec" ]; then
- exec @BINDIR@/lxc-unshare -s MOUNT -- $0 -n $name --exec "$@"
+if [ "$(id -u)" != "0" ]; then
+ echo "$(basename $0): must be run as root" >&2
+ exit 1
fi
if [ -z "$name" ]; then
@@ -45,51 +99,43 @@ if [ -z "$name" ]; then
exit 1
fi
+if [ -z "$exec" ]; then
+ exec @BINDIR@/lxc-unshare -s MOUNT -- $0 -n $name --exec "$@"
+fi
+
lxc-info -n $name 2>&1 | grep -q 'STOPPED'
if [ $? -eq 0 ]; then
- echo "Container $name is not running"
+ echo "$(basename $0): container '$name' is not running" >&2
exit 1
fi
-cgroups=$(mount -l -t cgroup)
-cgroup_path=""
-
-for i in "$cgroups"; do
-
- cgroup_name=$(echo $i | awk ' { print $1 } ')
- cgroup_path=$(echo $i | awk ' { print $3 } ')
-
- if [ "$cgroup_name" == "lxc" ]; then
- break;
- fi
-
-done
-
-if [ -z "$cgroup_path" ]; then
- cgroups=`grep -m1 -E '^[^ \t]+[ \t]+[^ \t]+[ \t]+cgroup' /proc/self/mounts`
- for i in "$cgroups"; do
- cgroup_path=$(echo $i | awk ' { print $2 } ')
- if [ -n $cgroup_path ]; then
- break;
- fi
- done
+get_parent_cgroup
+if [ ! -d "$parent_cgroup" ]; then
+ echo "$(basename $0): no cgroup mount point found" >&2
+ exit 1
fi
-if [ -z "$cgroup_path" ]; then
- echo "no cgroup mount point found"
- exit 1
+pid=$(head -1 $parent_cgroup/$name/tasks)
+
+if [ -z "$pid" ]; then
+ echo "$(basename $0): no process found for '$name'" >&2
+ exit 1
fi
-# the container will be in:
-# ${cgroup_path}.${init_cgroup_path}."lxc".$name
-init_cgroup=`cat /proc/1/cgroup | awk -F: '{ print $3 }' | head -1`
-final_cgroup_path=$cgroup_path/$init_cgroup/lxc
-pid=$(head -1 $final_cgroup_path/$name/tasks)
+tmpdir=$(mktemp -d)
-if [ -z "$pid" ]; then
- echo "no process found for '$name'"
- exit 1
+if [ -z "$tmpdir" -o ! -d "$tmpdir" ]; then
+ echo "$(basename $0): unable to create temporary directory" >&2
+ exit 1
fi
-mount -n --bind /proc/$pid/net /proc/$$/net && \
+# Bind mount /proc/$pid/net onto /proc/net before calling 'netstat'.
+# However, we can not simply bind mount on top of procfs, so we have
+# to move procfs out of the way first.
+mount -n --move /proc "$tmpdir" && \
+ mount -n -t tmpfs tmpfs /proc && \
+ mkdir /proc/root /proc/net && \
+ mount -n --move "$tmpdir" /proc/root && \
+ rmdir "$tmpdir" && \
+ mount -n --bind /proc/root/$pid/net /proc/net && \
exec netstat "$@"
--
1.7.4.1
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