[lmi-commits] [lmi] master b80b1ae 7/7: Experiment with bind mounts

[Greg Chicares]

branch: master
commit b80b1ae2edfabd6eb84a9c2db1320a64085674e8
Author: Gregory W. Chicares <address@hidden>
Commit: Gregory W. Chicares <address@hidden>

    Experiment with bind mounts
    
    It takes a little over forty minutes to run 'install_centos.sh'.
    Perhaps it would be faster if the host system's /var/cache could
    be used for apt and yum inside the (nested) chroots.
---
 install_centos.sh | 111 +++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 102 insertions(+), 9 deletions(-)

diff --git a/install_centos.sh b/install_centos.sh
index 0bec8e7..1dee78d 100755
--- a/install_centos.sh
+++ b/install_centos.sh
@@ -44,6 +44,21 @@ rinse --arch amd64 --distribution centos-7 \
   --directory /srv/chroot/centos7lmi \
   --mirror http://mirror.net.cen.ct.gov/centos/7.7.1908/os/x86_64/Packages \
 
+# There should be no bind mounts yet:
+findmnt --kernel -n --list | grep '\['
+
+# Now centos has its own cache directory, with subdirectories:
+ls /srv/chroot/centos7lmi/var/cache/yum
+ls /srv/chroot/centos7lmi/var/cache/yum/x86_64/7/
+# There's very little there--perhaps 49272 bytes:
+du -sb /srv/chroot/centos7lmi/var/cache/yum
+
+mkdir -p /var/cache/centos_lmi
+du -sb /var/cache/centos_lmi
+# 'rbind' seems necessary because centos uses subdirs
+mount --rbind /var/cache/centos_lmi /srv/chroot/centos7lmi/var/cache/yum || 
echo "Oops"
+findmnt --kernel -n --list | grep '\['
+
 cat >/srv/chroot/centos7lmi/tmp/setup0.sh <<EOF
 #!/bin/sh
 set -evx
@@ -66,36 +81,55 @@ getent passwd greg || useradd --gid=1000 --groups=greg 
--uid=1000 \
 mountpoint /dev/pts || mount -t devpts -o rw,nosuid,noexec,relatime,mode=600 
devpts /dev/pts
 mountpoint /proc    || mount -t proc -o rw,nosuid,nodev,noexec,relatime proc 
/proc
 
+du -sb /var/cache/yum
+
 yum --assumeyes install ncurses-term zsh
 chsh -s /bin/zsh root
 chsh -s /bin/zsh greg
 
+du -sb /var/cache/yum
+
 yum --assumeyes install centos-release-scl
 yum-config-manager --enable rhel-server-rhscl-7-rpms
+
+du -sb /var/cache/yum
+
 yum --assumeyes install devtoolset-8 rh-git218
 # In order to use the tools on the three preceding lines, do:
 #   scl enable devtoolset-8 rh-git218 $SHELL
 # and then they'll be available in that environment.
 
+du -sb /var/cache/yum
+
 # Install "EPEL". See:
 #   https://lists.nongnu.org/archive/html/lmi/2019-09/msg00037.html
 yum --assumeyes install ca-certificates curl nss-pem
 rpm -ivh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
 
+du -sb /var/cache/yum
+
 yum --assumeyes install schroot
 # To show available debootstrap scripts:
 #   ls /usr/share/debootstrap/scripts
 
+du -sb /var/cache/yum
+
 # Install a debian chroot inside this centos chroot.
 yum --assumeyes install debootstrap.noarch
 mkdir -p /srv/chroot/"${CHRTNAME}"
 debootstrap "${CODENAME}" /srv/chroot/"${CHRTNAME}" 
http://deb.debian.org/debian/
+
+du -sb /var/cache/yum
+
 echo Installed debian "${CODENAME}".
 EOF
 
 chmod +x /srv/chroot/centos7lmi/tmp/setup0.sh
 schroot --chroot=centos7lmi --user=root --directory=/tmp ./setup0.sh
 
+du -sb /var/cache/centos_lmi
+du -sb /srv/chroot/centos7lmi/var/cache/yum
+
 cp -a ~/.zshrc /srv/chroot/centos7lmi/root/.zshrc
 cp -a ~/.zshrc /srv/chroot/centos7lmi/home/greg/.zshrc
 
@@ -110,13 +144,20 @@ root-groups=root
 type=plain
 EOF
 
-mount --bind /var/cache/"${CODENAME}" 
/srv/chroot/centos7lmi/var/cache/apt/archives || echo "Oops"
-mount --bind /var/cache/"${CODENAME}" 
/srv/chroot/centos7lmi/var/cache/bullseye     || echo "Oops"
-# It would also be interesting to ascertain where the centos chroot
-# caches its files: /srv/chroot/centos7lmi/var/cache/yum/x86_64/ seems
-# likely, but is empty? No, wait:
-#   #du -sb /srv/chroot/centos7lmi/var/cache/yum
-#   119535116       /srv/chroot/centos7lmi/var/cache/yum
+# This seems to work perfectly:
+mkdir /srv/chroot/centos7lmi/srv/chroot/"${CHRTNAME}"/cache_for_lmi
+mount --bind /srv/cache_for_lmi 
/srv/chroot/centos7lmi/srv/chroot/"${CHRTNAME}"/cache_for_lmi || echo "Oops"
+findmnt --kernel -n --list | grep '\['
+
+# At this point, the debian chroot's /var/cache/apt/archives/
+# directory exists, but is empty:
+du -sb /srv/chroot/centos7lmi/srv/chroot/"${CHRTNAME}"/var/cache/apt/archives
+# The host's apt archives contain:
+du -sb /var/cache/"${CODENAME}"
+findmnt --kernel -n --list | grep '\['
+
+mount --bind /var/cache/"${CODENAME}" 
/srv/chroot/centos7lmi/srv/chroot/"${CHRTNAME}"/var/cache/apt/archives || echo 
"Oops"
+findmnt --kernel -n --list | grep '\['
 
 cat >/srv/chroot/centos7lmi/tmp/setup1.sh <<EOF
 #!/bin/sh
@@ -138,8 +179,19 @@ chmod +x lmi_setup_*.sh
 
 . ./lmi_setup_inc.sh
 
-mkdir -p /var/cache/"${CODENAME}"
-mount --bind /var/cache/"${CODENAME}" 
/srv/chroot/"${CHRTNAME}"/var/cache/apt/archives || echo "Oops"
+set -vx
+
+# Just get rid of this stanza?
+# mkdir -p /var/cache/"${CODENAME}"
+# mountpoint /var/cache/apt/archives || mount --bind /var/cache/"${CODENAME}" 
/srv/chroot/"${CHRTNAME}"/var/cache/apt/archives || echo "Oops"
+# mountpoint: /var/cache/apt/archives: No such file or directory
+# This stanza (now suppressed) looks like a possible cause of the
+# circular bind mounts demonstrated below (search for "eraseme-findmnt"):
+# + mount --bind /var/cache/bullseye 
/srv/chroot/lmi_bullseye_1/var/cache/apt/archives
+
+# At this point, the debian chroot's /var/cache/apt/archives/
+# directory exists, but is empty:
+du -sb /srv/chroot/"${CHRTNAME}"/var/cache/apt/archives
 
 # ./lmi_setup_10.sh
 # ./lmi_setup_11.sh
@@ -156,9 +208,50 @@ EOF
 chmod +x /srv/chroot/centos7lmi/tmp/setup1.sh
 schroot --chroot=centos7lmi --user=root --directory=/tmp ./setup1.sh
 
+du -sb /srv/chroot/centos7lmi/srv/chroot/"${CHRTNAME}"/var/cache/apt/archives
+du -sb /var/cache/"${CODENAME}"
+findmnt --kernel -n --list | grep '\['
+
 stamp1=$(date -u +'%Y-%m-%dT%H:%M:%SZ')
 echo "Finished: $stamp1"
 
 seconds=$(($(date '+%s' -d "$stamp1") - $(date '+%s' -d "$stamp0")))
 elapsed=$(date -u -d @"$seconds" +'%H:%M:%S')
 echo "Elapsed: $elapsed"
+
+cat >/tmp/eraseme-findmnt <<EOF
+/root[0]#findmnt --kernel -n --list | grep '\[' |sort
+/srv/chroot/centos7lmi/srv/chroot/lmi_bullseye_1/var/cache/apt/archives 
/dev/sdb5[/srv/chroot/centos7lmi/var/cache/bullseye] ext4       
rw,relatime,errors=remount-ro
+/srv/chroot/centos7lmi/srv/chroot/lmi_bullseye_1/var/cache/apt/archives 
/dev/sdb5[/var/cache/bullseye]                       ext4       
rw,relatime,errors=remount-ro
+/var/cache/bullseye                                                     
/dev/sdb5[/srv/chroot/centos7lmi/var/cache/bullseye] ext4       
rw,relatime,errors=remount-ro
+/root[0]#
+/root[0]#du -sb 
/srv/chroot/centos7lmi/srv/chroot/lmi_bullseye_1/var/cache/apt/archives
+593658728       
/srv/chroot/centos7lmi/srv/chroot/lmi_bullseye_1/var/cache/apt/archives
+/root[0]#du -sb /srv/chroot/centos7lmi/var/cache/bullseye
+593658728       /srv/chroot/centos7lmi/var/cache/bullseye
+/root[0]#du -sb /var/cache/bullseye
+593658728       /var/cache/bullseye
+/root[0]#
+/root[0]#umount /var/cache/bullseye
+/root[0]#du -sb /var/cache/bullseye
+682609842       /var/cache/bullseye
+/root[0]#
+/root[0]#findmnt --kernel -n --list | grep '\[' |sort
+/srv/chroot/centos7lmi/srv/chroot/lmi_bullseye_1/var/cache/apt/archives 
/dev/sdb5[/var/cache/bullseye] ext4       rw,relatime,errors=remount-ro
+/root[0]#du -sb 
/srv/chroot/centos7lmi/srv/chroot/lmi_bullseye_1/var/cache/apt/archives
+682609842       
/srv/chroot/centos7lmi/srv/chroot/lmi_bullseye_1/var/cache/apt/archives
+/root[0]#du -sb /srv/chroot/centos7lmi/var/cache/bullseye
+593658728       /srv/chroot/centos7lmi/var/cache/bullseye
+/root[0]#
+/root[0]#du -sb 
/srv/chroot/centos7lmi/srv/chroot/lmi_bullseye_1/var/cache/apt/archives
+682609842       
/srv/chroot/centos7lmi/srv/chroot/lmi_bullseye_1/var/cache/apt/archives
+/root[0]#du -sb /srv/chroot/centos7lmi/var/cache/bullseye
+593658728       /srv/chroot/centos7lmi/var/cache/bullseye
+/root[0]#umount 
/srv/chroot/centos7lmi/srv/chroot/lmi_bullseye_1/var/cache/apt/archives
+/root[0]#du -sb 
/srv/chroot/centos7lmi/srv/chroot/lmi_bullseye_1/var/cache/apt/archives
+49157474        
/srv/chroot/centos7lmi/srv/chroot/lmi_bullseye_1/var/cache/apt/archives
+/root[0]#du -sb /srv/chroot/centos7lmi/var/cache/bullseye
+593658728       /srv/chroot/centos7lmi/var/cache/bullseye
+/root[0]#du -sb /var/cache/bullseye
+682609842       /var/cache/bullseye
+EOF