Tech Blog of Stephen Souness

Introduction This post is about situations where software components that are commonly imported in as part of assembling production systems can slip outside of the normal expected path for detecting the availability and applying version upgrades. A couple of examples of systems that can be set up to detect when new versions of dependencies are available are: Renovate Dependabot Examples of dependency changes When a base Docker image went distroless When new versions stopped being released for the alpine distribution of the envoyproxy Docker image automation had nothing in place to detect that and raise it as a potential issue. I came across this when a production issue came up in another team's core infrastructure service. Since my team was going to be blocked until the incident wsa resolved, I followed the online chat discussion, checked some logs, did some Googling and established that the error that was being seen should have been resolved by a version of envoy that had been ava...

During my time in London I socialised a bit with some of the members of the team behind the LMAX Disruptor, which is where I first recall hearing of the concept of  Mechanical Sympathy  and its applicattion to design of software. Something that was intially counterintuitive to me about the Disruptor was the approach to including padding in data structures to exploit caching at the hardware level. I'm on a break from working in tech at the moment as I keep myself available to help my family adjust to some health issues that come with aging, but my mechanical sympathy mindset is still active. Today as I was vacuuming the floor of my living room I wondered about whether height makes a difference to the suction power of the vacuum cleaner - as taller people will typically extend the length of the pipe between the suction mechanism and the floor. Based on some Google search results, the short answer is "yes". I was going to posit that as an explanation for why my mother always...