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Récup. creation-template-lxc-debian-buster.md

Chl 2020-01-30 19:27:40 +01:00
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# Template LXC unprivileged de Debian 10 _Buster_
Création d'un conteneur/template LXC unprivileged de Debian 10 dans une Debian 10 sur une partition Btrfs.
Avertissements liminaires :
- `lxc-create -t debian` dit explicitement ne pas gérer les conteneurs non-privilégies, cependant je n'ai trouvé aucune contre-indication à créer le template privilégie et faire un _uidshift_ maison. C'est la piste détaillée ici.
- une autre piste consiste à partir d'un `debootstrap` et faire le travail manuellement. Il faut cependant penser à initialiser pas mal de petites choses comme pour openvz (locales, fuseau horaire, `/etc/machine-id`, etc.)
- ce tuto est en bêta : écrit d'une traite et, aujourd'hui, pas encore relu ni réutilisé. Caveat emptor.
## Création du template
On commence par créer un répertoire de cache dans le même volume BtrFs, puis on lance la commande de création :
```
cd /home/ltorvalds/lxc
mkdir cache
LXC_CACHE_PATH=/home/ltorvalds/lxc/cache MIRROR=http://apt-proxy.example.net:3142/debian SECURITY_MIRROR=http://apt-proxy.example.net:3142/debian lxc-create -n debian-buster-lxccreate -P /home/ltorvalds/lxc -t debian -B btrfs -- -r buster
```
Quelques erreurs `update-rc.d` et `invoke-rc.d`, on a un magnifique template. On le complète ainsi :
```
# nettoyage
btrfs subvol delete cache/debian/rootfs-buster-amd64
rm -rf cache/
# droits
chown 100000:ltorvalds debian-buster-lxccreate
chown ltorvalds:ltorvalds debian-buster-lxccreate/config
# Repris de https://unix.stackexchange.com/questions/127554/building-unprivileged-userns-lxc-container-from-scratch-by-migrating-a-privil/420317#420317
export SUBUID=100000
export SUBGID=100000
#find debian-buster-lxccreate/rootfs | while read i; do CURRENT_UID=$(stat --format=%u $i); CURRENT_GID=$(stat --format=%g $i); NEW_SUBUID=$((CURRENT_UID+SUBUID)); NEW_SUBGID=$((CURRENT_GID+SUBGID)); echo "chown -h $NEW_SUBUID.$NEW_SUBGID $i"; done
# Version "noms-de-fichiers-bizarres". Attention bashism sur 'read -d'.
find debian-buster-lxccreate/rootfs -print0 | while IFS= read -r -d '' i; do CURRENT_UID=$(stat --format=%u "$i"); CURRENT_GID=$(stat --format=%g "$i"); NEW_SUBUID=$((CURRENT_UID+SUBUID)); NEW_SUBGID=$((CURRENT_GID+SUBGID)); chown -h $NEW_SUBUID.$NEW_SUBGID "$i"; done
```
### Adaptation de la configuration
On remplace la config par :
```
# Template used to create this container: /usr/share/lxc/templates/lxc-debian
# Parameters passed to the template: -r buster
# Template script checksum (SHA-1): 5a35ad98c578f5487dc5712a1c7d38af399be813
# For additional config options, please look at lxc.container.conf(5)
# Uncomment the following line to support nesting containers:
#lxc.include = /usr/share/lxc/config/nesting.conf
# (Be aware this has security implications)
# Distribution configuration
lxc.include = /usr/share/lxc/config/debian.common.conf
lxc.include = /usr/share/lxc/config/debian.userns.conf
lxc.arch = linux64
# Container specific configuration
lxc.tty.max = 4
lxc.arch = amd64
lxc.pty.max = 1024
lxc.include = /etc/lxc/default.conf
lxc.idmap = u 0 100000 1000
lxc.idmap = g 0 100000 1000
lxc.idmap = u 1000 1000 1
lxc.idmap = g 1000 1000 1
lxc.idmap = u 1001 101001 64534
lxc.idmap = g 1001 101001 64534
lxc.mount.auto = proc:mixed sys:ro cgroup:mixed
# FS configuration
lxc.rootfs.path = btrfs:/home/ltorvalds/lxc/debian-buster-lxccreate/rootfs
# Point de montage à partager avec l'hôte
#lxc.mount.entry = /home/ltorvalds/dev/project-ro home/ltorvalds/dev/project-ro none ro,bind,create=dir 0 0
#lxc.mount.entry = /home/ltorvalds/dev/project-rw home/ltorvalds/dev/project-rw none bind,create=dir 0 0
# Network configuration
lxc.uts.name = debian-buster-lxccreate
#lxc.net.0.type = empty
lxc.net.0.type = veth
lxc.net.0.link = br0
lxc.net.0.flags = up
lxc.net.0.hwaddr = 00:FF:3e:99:99:99
lxc.net.0.ipv4.address = 192.168.1.199/25
lxc.net.0.ipv4.gateway = 192.168.1.1
lxc.net.0.ipv6.address = 2a01:1234:1234:1234::1:99/112
lxc.net.0.ipv6.gateway = 2a01:1234:1234:1234::1:1
# Profil Apparmor
# Pour Debian Buster, il semble qu'on soit obligé de passer en unconfined
# (note 2020-01-22 : ben c'est bon maintenant ?)
lxc.apparmor.profile = lxc-container-default-cgns
#lxc.apparmor.profile = unconfined
#lxc.apparmor.profile = generated
#lxc.apparmor.allow_nesting = 1
```
Pour mémoire, au niveau système :
```
# cd /etc; tail -n 1000 lxc/* sub???
==> lxc/default.conf <==
lxc.net.0.type = empty
lxc.apparmor.profile = generated
lxc.apparmor.allow_nesting = 1
==> lxc/lxc-usernet <==
ltorvalds veth br0 10
==> subgid <==
ltorvalds:100000:65536
ltorvalds:200000:65536
ltorvalds:300000:65536
ltorvalds:400000:65536
ltorvalds:500000:65536
ltorvalds:600000:65536
ltorvalds:700000:65536
ltorvalds:800000:65536
ltorvalds:900000:65536
ltorvalds:1000:1
==> subuid <==
ltorvalds:100000:65536
ltorvalds:200000:65536
ltorvalds:300000:65536
ltorvalds:400000:65536
ltorvalds:500000:65536
ltorvalds:600000:65536
ltorvalds:700000:65536
ltorvalds:800000:65536
ltorvalds:900000:65536
ltorvalds:1000:1
```
### Adaptation à l'intérieur du conteneur
On lance le conteneur et on s'y projette :
```
lxc-start -n debian-buster-lxccreate
# FIXME : quelques erreurs systemd à déboguer en mode --foreground
# [FAILED] Failed to listen on Journal Audit Socket
# [FAILED] Failed to mount Kernel Debug File System. (/sys/kernel/debug)
lxc-attach -n debian-buster-lxccreate
su -
cd /etc
dpkg-reconfigure debconf
apt install git --no-install-recommends
cat <<EOF >.gitignore
/ld.so.cache
/adjtime
/nologin
/.pwd.lock
*-
*~
*.old
*-old
EOF
git init
chmod 0700 .git
git add .
git commit -a -m "commit initial"
apt install less vim
update-alternatives --config editor
apt install nullmailer # "" / mail.example.net / postmaster@example.net
rm mailname && ln -s hostname mailname # pas très orthodoxe :-/
apt install iptables-persistent netcat-openbsd
# Rechercher ~/.ssh/git-read-only , puis...
cat <<EOF >~/.ssh/config
# /root/.ssh/config
Host code.bugness.org
IdentityFile ~/.ssh/git-read-only
EOF
cd /usr/local/share
git clone ssh://gb@code.bugness.org:2020/chl/scripts-admin-quickndirty-public.git scripts-admin
cd /etc
cat <<EOF >/etc/apt/apt.conf.d/44proxy
Acquire::http::Proxy-Auto-Detect "/usr/local/share/scripts-admin/apt-conf-proxy.sh";
EOF
# Vérifier que /etc/apt/sources.list soit a peu près ok :
# deb http://ftp.fr.debian.org/debian buster main
# deb http://ftp.fr.debian.org/debian buster-updates main
# deb http://security.debian.org buster/updates main
```
### Reconfiguration automatique
```
cat <<EOF >
[Unit]
Description=Regenerate OpenSSH server keys
#ConditionPathExists=!/etc/ssh/ssh_host_rsa_key
Before=network.target
[Service]
Type=oneshot
ExecStart=/bin/bash -c "(/bin/date; echo $(( $RANDOM * $RANDOM * $RANDOM * $RANDOM )) )| /usr/bin/md5sum | /usr/bin/cut -f 1 -d ' ' >/etc/machine-id"
ExecStart=/bin/sh -c "/bin/rm -vf /etc/ssh/ssh_host_*"
ExecStart=/usr/sbin/dpkg-reconfigure openssh-server
ExecStartPost=-/bin/bash -c "/bin/systemctl disable reset-ssh-server-keys"
ExecStartPost=/bin/rm -f /etc/systemd/system/reset-ssh-server-keys.service
TimeoutSec=120
RemainAfterExit=no
[Install]
WantedBy=multi-user.target
EOF
systemctl enable reset-ssh-server-keys
```
## Utilisation courante
On peut ensuite profiter du template en tant qu'utilisateur simple via :
```
lxc-copy -n debian-buster-lxccreate -N project1234-dev
# The MAC address will be changed by LXC but remember to affect a new IP
# and possibly new subuid (but that topic will be for another day).
```