Posted in 2019

EnvironmentFiles used by systemd

In a previous posting, Environment variables set by systemd, variables were directly set within the systemd unit file. This is fine for a small amount of modifications, but in some case these environment variables are provided by another package on the system or need to be the same for multiple services.

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Environment variables set by systemd

Applications sometimes need environment variables to be set for triggering certain behavior like giving debug output or to route traffic via a HTTP-proxy for example. A common way is to modify the start-stop script, but with systemd on most Linux systems, like Debian and Red Hat based distributions, this can also directly set within the unit file and you don’t have to export the variables anymore.

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Connecting to legacy servers with OpenSSH

Phasing out legacy cryptographic algorithms can always be an interesting endeavor as terminating to early breaks stuff and to late it can lead to a compromise. OpenSSH disabled DSA with version 7.0 in March 2015 as 5 years earlier it was discovered that DSA was compromised and labelled as insecure. Normally this shouldn’t be a problem with a normal software life cycle, but sometimes you will encounter a legacy box that will not be upgraded as it will break things. Now it will stop new connections being setup from upgraded to machines as with SSH.

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Setting a different libvirt uri for Vagrant

HashiCorp Vagrant normally selects the right hypervisor, but the version shipped with Fedora 30 prefers to run within the QEMU user session of the hypervisor. A .Vagrantfile it would match the default behavior which doesn’t require any system privileges is shown below.

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Using bare variables in Ansible 2.8

Ansible 2.8 was released in May 2019 and later in May came to Fedora 30 in package form. So the first tests could be done to see what needed to be done to switch from 2.7 to 2.8 and don’t generate a lot of stopped GitLab CI-jobs due to new warnings and errors. So let start with one warning that needs to be resolved before the 2.12 release and also is given on many third-party roles.

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Redirecting to mobile Wikipedia

Wikipedia both has a traditional and progressive website that is shown on mobile devices. After years the progressive website is still not shown on desktops sadly enough, but with a browser plugin a redirect can be triggered to the mobile site in most browsers. This as the Redirector plugin works at least in Mozilla Firefox, Google Chrome and Chromium, and will most likely also work in future when Microsoft Edge switches to the Chromium engine.

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Using YUM history to see package changes

When you install or update packages on your system, then changes may occur that were not expected. Recent security updates on a server and left Nagios in a failed state, but what exactly happened, and can it be traced back as yum-cron installs all required security updates? Luckily YUM keeps a history database of all actions and with yum history can you list all transactions.

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Check HTTP with telnet

HTTPS may become the standard quickly, but HTTP is still the base, and understanding how to verify an HTTP server without a web browser can be very useful. A lot of situations simply don’t allow you to install a web browser or gives only a blank page.

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PHP 7.3 and forbidden functions

Last month PHP 7.3.0 was released and with that a lot of functions or aliases were deprecated that may lead to issues down the road. While Xdebug still needs to be released for PHP 7.3 an automated test with GitLab isn’t possible yet as the build phase of Xdebug fails. Luckily I’m using PHP Code Sniffer and extending phpcs.xml.dist with the lines below make the build already fail if any of the forbidden functions are being used in the code.

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