[lxc-devel] [PATCH] ubuntu-cloud-prep: improve overlayfs workaround

[Serge Hallyn]

Quoting Scott Moser (smoser at ubuntu.com):
> the previous 'patch_start' can be vastly simplified now that I better
> understand what the bug was.  Instead of wrapping 'start', we only
> need to ensure that /etc/init exists inside the overlayfs, so that the
> directory that upstart watches is guaranteed to be in the overlay, not
> the underlay.
> 
> The problem is described under bug 1213925.
> 
> Signed-off-by: Scott Moser <smoser at ubuntu.com>

Thanks, looks good.

Acked-by: Serge E. Hallyn <serge.hallyn at ubuntu.com>

> ---
>  hooks/ubuntu-cloud-prep | 69 +++++++++----------------------------------------
>  1 file changed, 12 insertions(+), 57 deletions(-)
> 
> diff --git a/hooks/ubuntu-cloud-prep b/hooks/ubuntu-cloud-prep
> index a6999b6..c4c3620 100755
> --- a/hooks/ubuntu-cloud-prep
> +++ b/hooks/ubuntu-cloud-prep
> @@ -35,56 +35,9 @@ Usage: ${0##*/} [options] root-dir
>  EOF
>  }
>  
> -write_patched_start() {
> -    cat > "$1" <<"EOF"
> -#!/bin/bash
> -## This is a wrapper around upstart's /sbin/start to ensure that
> -## calling 'start' on a job after writing it to /etc/init will function
> -## correctly despite broken/missing support for inotify in overlayfs.
> -##
> -real() { exec -a /sbin/start "/sbin/start.real" "$@"; }
> -
> -# no args or not root
> -[ $# -ne 0 -a "$UID" = "0" ] || real "$@"
> -
> -job=""
> -# find first argument that doesn't start with '-' as 'job'
> -for x in "$@"; do
> -  [ "${x#-}" = "$x" ] && { job="$x"; break; }
> -done
> -
> -# if job isn't there, no reason to check further
> -[ -n "$job" ] && [ -f "/etc/init/$job.conf" ] || real "$@"
> -
> -# on Unknown, 'status' exits 1, and prints 'Unknown job' to stderr.
> -out=$(status "$@" 2>&1)
> -[ $? -eq 1 -a "${out#*nknown job}" != "$out" ] || real "$@"
> -
> -initctl reload-configuration >/dev/null 2>&1
> -real "$@"
> -EOF
> -    chmod 755 "$1"
> -}
> -
> -patch_start() {
> -    # patch /sbin/start inside root_d to deal with lack of inotify
> -    local root_d="$1"
> -
> -    # already patched
> -    [ -f "$root_d/sbin/start.real" ] &&
> -        { debug 1 "$root_d 'start' seems already patched"; return 1; }
> -
> -    debug 1 "patching /sbin/start in $root_d"
> -    chroot "$root_d" dpkg-divert --local --rename \
> -        --divert /sbin/start.real --add /sbin/start ||
> -        { error "failed to patch /sbin/start for overlayfs"; return 1; }
> -
> -    write_patched_start "$root_d/sbin/start"
> -}
> -
>  prep() {
>      local short_opts="Chi:L:S:u:v"
> -    local long_opts="auth-key:,cloud,help,hostid:,name:,nolocales:,patch-start,userdata:,verbose"
> +    local long_opts="auth-key:,cloud,help,hostid:,name:,nolocales:,create-etc-init,userdata:,verbose"
>      local getopt_out getopt_ret
>      getopt_out=$(getopt --name "${0##*/}" \
>          --options "${short_opts}" --long "${long_opts}" -- "$@" 2>/dev/null) ||
> @@ -97,7 +50,7 @@ prep() {
>  
>      local cur="" next=""
>      local userdata="" hostid="" authkey="" locales=1 cloud=0 name=""
> -    local patch_start=0
> +    local create_etc_init=0
>  
>      while [ $# -ne 0 ]; do
>          cur="$1"; next="$2";
> @@ -107,7 +60,7 @@ prep() {
>                 --name) name="$next";;
>              -i|--hostid) hostid="$next";;
>              -L|--nolocales) locales=0;;
> -               --patch-start) patch_start=1;;
> +               --create-etc-init) create_etc_init=1;;
>              -S|--auth-key)
>                  [ -f "$next" ] ||
>                      { error "--auth-key: '$next' not a file"; return 1; }
> @@ -137,8 +90,10 @@ prep() {
>          error "${0##*}: usage failed, continuing with defaults"
>      fi
>  
> -    [ "$patch_start" -eq 0 ] || patch_start "$root_d" ||
> -        { error "failed to patch start for overlayfs"; return 1; }
> +    [ "$create_etc_init" -eq 0 ] ||
> +        echo "#upstart needs help for overlayfs (LP: #1213925)." > \
> +            "$root_d/etc/init/.overlayfs-upstart-helper" ||
> +        { error "failed to create /etc/init in overlay"; return 1; }
>  
>      local seed_d=""
>      seed_d="$root_d/var/lib/cloud/seed/nocloud-net"
> @@ -203,13 +158,13 @@ main() {
>      local _LXC_HOOK
>      if [ -n "$LXC_ROOTFS_MOUNT" -a "$3" = "clone" ]; then
>          _LXC_HOOK="clone"
> -        local name="$1" pstart=""
> +        local name="$1" create_etc_init=""
>          shift 3
> -        # if mountpoint is overlayfs then add '--patch-start'
> +        # if mountpoint is overlayfs then add '--create-etc-init'
>          [ "${LXC_ROOTFS_PATH#overlayfs}" != "${LXC_ROOTFS_PATH}" ] &&
> -           pstart="--patch-start"
> -        debug 1 prep "--name=$name" $pstart "$LXC_ROOTFS_MOUNT" "$@"
> -        prep "--name=$name" $pstart "$LXC_ROOTFS_MOUNT" "$@"
> +           create_etc_init="--create-etc-init"
> +        debug 1 prep "--name=$name" $create_etc_init "$LXC_ROOTFS_MOUNT" "$@"
> +        prep "--name=$name" $create_etc_init "$LXC_ROOTFS_MOUNT" "$@"
>      else
>          _LXC_HOOK=""
>          prep "$@"
> -- 
> 1.8.3.2
> 
> 
> ------------------------------------------------------------------------------
> Get 100% visibility into Java/.NET code with AppDynamics Lite!
> It's a free troubleshooting tool designed for production.
> Get down to code-level detail for bottlenecks, with <2% overhead. 
> Download for free and get started troubleshooting in minutes. 
> http://pubads.g.doubleclick.net/gampad/clk?id=48897031&iu=/4140/ostg.clktrk
> _______________________________________________
> Lxc-devel mailing list
> Lxc-devel at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/lxc-devel