Ubuntu

Recently I was investigating quite an interesting issue - there is Ubuntu based VM our testers run some tests on. It was reported they’re unable to log into the virtual machine.

After a brief investigation it became clear the issue is not network or SSH key related.

These are records from auth log:

/var/log/auth.log

Feb 28 20:21:39 test-instance sshd[21954]: pam_unix(sshd:session): session opened for user ubuntu by (uid=0)
Feb 28 20:21:39 test-instance systemd-logind[756]: New session 75 of user ubuntu.
Feb 28 20:21:39 test-instance sshd[21954]: fatal: fork of unprivileged child failed
Feb 28 20:21:39 test-instance systemd-logind[756]: Removed session 75.

Quite an obscure error message, but smells like cgroup problem. Indeed:

Have Ubuntu 14.04 installed on the VM I use as a programming/testing environment.

Golang packages in Ubuntu 14.04 repo are a bit old:

It appears lot of my colleagues think they’ll get the name of any service in Ubuntu system autocompleted by typing service first_few_letters_of_service_name and pressing Tab button. When this does not work (and it does not work a lot) it creates a lot of confusion and rises lot of questions.

In Ubuntu 14.04, the script that handles completions for service command is /usr/share/bash-completion/bash_completion It looks for service names as files in /etc/rc.d/init.d, /etc/init.d, and in the output of systemctl list-units --full --all

Recently hit quite an annoying bug in vmbuilder, tool that allows to build Ubuntu based virtual machines.

Was trying to build a VM using the following command:

vmbuilder kvm ubuntu --suite trusty --flavour virtual --arch amd64 --mem 8192 --rootsize 8000 --dest /var/lib/libvirt/images --libvirt qemu:///system --hostname new-host --user jenkins --name jenkins --pass <jenkins_user_password> --addpkg openssh-server --addpkg git --addpkg acpid

but kernel installation failed with the following error:

Unpacking linux-image-virtual (3.13.0.53.60) ...
, stderr: grep: /proc/cpuinfo: No such file or directory
This kernel does not support a non-PAE CPU.

Wasted lot of time today trying to figure out why ssh on some server still allows to log in with password despite the fact that in /etc/ssh/sshd_config password based log in is disabled:

PasswordAuthentication no