[lxc-users] Trying to create a lxc container for running Visual Studio Code

[Serge E. Hallyn]

On Thu, Feb 11, 2021 at 10:22:52PM +0100, Peter Carlsson wrote:
> On Thu, Feb 11, 2021 at 11:54:05AM -0600, Serge E. Hallyn wrote:
> > On Wed, Feb 10, 2021 at 10:49:55PM +0100, Peter Carlsson wrote:
> > > On Wed, Feb 10, 2021 at 07:08:09AM -0600, Serge E. Hallyn wrote:
> > > 
> > > Hello again!
> > > 
> > > Thanks for your help.
> > > 
> > > I decided to start fresh and create the container as unprivileged. I
> > > therefor deleted the old thread.
> > > 
> > > Here is basically what I did:
> > > 
> > > As root:
> > > 
> > >   usermod -v 100000-200000 -w 100000-200000 peter
> > >   cat /etc/subuid
> > >     peter:100000:100001
> > >   cat /etc/subgid
> > >     peter:100000:100001
> > > 
> > >   nano /etc/sysctl.conf
> > >     # Added by Peter Carlsson 2021-02-10 for lxc
> > >     kernel.unprivileged_userns_clone=1
> > > 
> > >   nano /etc/default/lxc-net
> > >     #USE_LXC_BRIDGE="true"
> > > 
> > >   nano /etc/lxc/default.conf
> > >     lxc.net.0.type = veth
> > >     lxc.net.0.link = lxcbr0
> > >     lxc.net.0.flags = up
> > > 
> > >     lxc.apparmor.profile = generated
> > >     lxc.apparmor.allow_nesting = 1
> > > 
> > > As user peter:
> > > 
> > >   mkdir /home/peter/.config/lxc
> > >   nano /home/peter/.config/lxc/default.conf
> > >     lxc.net.0.type = veth
> > >     lxc.net.0.link = lxcbr0
> > >     lxc.net.0.flags = up
> > > 
> > >     lxc.apparmor.profile = generated
> > >     lxc.apparmor.allow_nesting = 1
> > > 
> > >     lxc.idmap = u 0 100000 100001
> > >     lxc.idmap = g 0 100000 100001
> > 
> > This all looks good.
> > 
> > > Don't know if this was necessary but I ran this after reading a link found on Google
> > > 
> > >   lxc-usernsexec
> > 
> > Sorry I'm not following here.  lxc-usernsexec without any arguments
> > will put you in a shell in a user namespace.  I assume you exited that
> > before going on with lxc-create, right?
> 
> Never mind. To try to solve my problems I googled and tried out
> different advices but this was something I don't think I did anything
> successful with.
> 
> > >   lxc-create -t download -n VisualStudioCode -- -d debian -r buster -a amd64
> > > 
> > >   lxc-start -n VisualStudioCode -F
> > >  
> > >     lxc-start: VisualStudioCode: network.c: lxc_create_network_unpriv_exec: 2178 lxc-user-nic failed to configure requested network: No such file or directory - Failed to open "/etc/lxc/lxc-usernet"
> > >     cmd/lxc_user_nic.c: 1296: main: Quota reached
> > >     lxc-start: VisualStudioCode: start.c: lxc_spawn: 1777 Failed to create the configured network
> > >     lxc-start: VisualStudioCode: start.c: __lxc_start: 1951 Failed to spawn container "VisualStudioCode"
> > >     lxc-start: VisualStudioCode: tools/lxc_start.c: main: 330 The container failed to start
> > >     lxc-start: VisualStudioCode: tools/lxc_start.c: main: 336 Additional information can be obtained by setting the --logfile and --logpriority options
> > > 
> > > What should I put in /etc/lxc/lxc-usernet?
> > 
> > cat << EOF | sudo tee /etc/lxc/lxc-usernet
> > # USERNAME TYPE BRIDGE COUNT
> > peter veth lxcbr0 10
> > 
> > > Do you see something else I have missed or should have done differently?
> > 
> > Not offhand.  But do make sure that lxc-net is running, i.e. make sure
> > that 'brctl show' shows lxcbr0
> > 
> > > Note that I had the network working for the container created by root.
>  
> Now I have also done these things and had some progress:
> 
>   systemctl enable lxc-net
>   systemctl start lxc-net
> 
>   nano /etc/lxc/lxc-usernet
>     # USERNAME TYPE BRIDGE COUNT
>     peter veth lxcbr0 10
> 
>   chmod 755 /home/peter/.local/share/
>   chmod 755 /home/peter/.local/share/lxc/
> 
>   lxc-start -n VisualStudioCode -F
>     Failed to mount cgroup at /sys/fs/cgroup/systemd: Permission denied
>     [!!!!!!] Failed to mount API filesystems.
>     Exiting PID 1...
> 
> For me it is not obvious what my next step should be. Any help would be
> appreciated.

serge at sl /etc/pam.d$ dpkg -l | grep cgfs
ii  libpam-cgfs                                1:4.0.3+master~20200706-1105-0ubuntu1~eoan amd64        PAM module for managing cgroups for LXC

Do you have something like this?  If so, then /etc/pam.d/common-session should have
a line like

common-session:session  optional        pam_cgfs.so -c freezer,memory,name=systemd

which is what should delegate the cgroups you need to create containers.

-serge