Linux

At work we have started to set up new continuous integration servers. We have decided to build the whole setup based on into individual Jenkins instance managed via Docker. Moreover, most build slaves on the instances are dynamically-created Docker containers themselves. To spawn up these slaves, the Jenkins masters need write access to the Docker socket. Of course, this would be a security implication if they had access to the socket of the main Docker daemon on the host that operates all services, including the Jenkins instances themselves. Thus, we added a second daemon to the host just for the purpose of executing the volatile build slaves. However, we soon noticed that containers executed on this additional daemon frequently showed DNS resolution errors. The remainder of this post will explain the details of how we tried to track down this problem with all the ugly details being involved there. ...

Since a few years I am maintaining autosuspend, a small daemon that automatically suspends a Linux system in case no activity is detected. With version 2.0 I have added support for scheduled wake ups based on configurable checks for pending activities. ...

Since an issue with the keyboard freezing for Android disk encryption was fixed in the Omnirom code base, I was able to upgrade my system again. Unfortunately, the system didn’t boot anymore without a factory reset. Therefore, I finally found out to manually restore individual apps from a system backup performed with TWRP. ...

Since two or three years I am experimenting with different solutions for my personal home entertainment system. Now that the solution has become quite stable I am going to describe my current setup and its evolution in this blog post hoping that someone might find it useful. ...

A few months ago I sold my existing basic Synology NAS and built my own one based on a power-efficient Intel CPU inside a mini ITX system with a usual Linux as the operating system. This provided me with a lot more flexibility and e.g. possibilities to encrypt my data properly. One thing I needed for this custom solution was a daemon to suspend the system in case of inactivity to further reduce the power consumption. I found a few existing scripts online, started using one of them, but soon had to modify it deeply until it was general enough to suit my needs. Today, I finally took the time to clean up the last issues in the code base and the autosuspend project is now available on Github. ...

I am constantly using several different computers (home, work, servers) and synchronizing the configurations of the shell and all other command line utilities I am using across these computers can be a bit challenging. Manually copying everything including all changes constantly appearing in the different configuration files is the worst solution. So I have been using a repository on my self-hosted Seafile server with all the required dotfiles and a custom setup script to create the required symlinks to these files. This worked quite well but also had several drawbacks. Therefore, I recently switched to homeshick to manage my dotfiles and, during this process, published most of my dotfiles on GitHub. ...

As I am working on a lot of different computer I wanted to share some of my configuration files across these computers to have similar working environments on all of the machines. An easy solution to do this is e.g. for git to put the .gitconfig file (along with other configuration files) into a folder inside the Dropbox (or other syncing tool), create a symlink to that file in the original location in your home directory and let Dropbox do the syncing. ...

After switching my computers to Arch Linux, reusing the existing home directories, I had the problem that the bash did not replace the user’s home directory with the tilde character (~) in the prompt. The solutions for this problem is easy: somewhere in the bash-internals a check tests whether the output of pwd matches the contents of $HOME. $HOME, in turn, is filled from the user definition in /etc/passwd. pwd always returns the current working directory without a trailing slash, but the entry for my user in /etc/passwd contained a trailing slash. Removing this slash from the file solves the problem and the prompt uses ~ again for the home directory. ...

Since the update to Ubuntu/Kubuntu Maverick Meerkat I was a bit puzzled why Thunderbird refused to open links in mails with my default browser Firefox even though it was set in the KDE settings and registered as a protocol-handler for http and https in the Thunderbird settings. It seems that there must be another setting in Thunderbird to use the default browser selected for the freedesktop environment which is now used. So updating the alternatives helped in Ubuntu: ...