Maybe I’m crazy, but I have an urge to start upgrading! The journey to containerisation has taken a while and one thing I’ve kept constant so far is the version of Apache, PHP, Perl, etc in the containers I’ve built. There are new versions of some of these packages that I can start to use now. For example, my web server container image is based on PHP 8.2.19 and I would like to start testing v8.3 so that I don’t leave it until the last minute when v8.2 starts going end of life.
One of the good things about container images is that they (can) have versions and when I define a container using an image I can specify which version I want to use. For example, I’m currently running nine Apache+PHP web server containers (of my design…there are some other web servers too). They’re using an image version that I’ve called ‘stable’. It’s a version which has proved to work well so far.
I’ll now build a new Apache+PHP container image, lets call it v2.0, that uses the latest versions of Apache and PHP, plus all the latest PHP modules that are built in. I can then modify just one, less significant, web server (one of my personal ones) to use v2.0 rather than the stable version. The other web servers continue running ‘stable’ alongside the new v2.0 test web server and they happily co-exist. That can be done on a non-container based server, but it’s not as easy to achieve, and easy to mess up all the servers at once if you make a mistake!
If I find v2.0 has problems I can quickly switch back to using ‘stable’…the switch would take me about 30 seconds. Conversely if after testing, perhaps on a few more less significant web servers, I find that v2.0 works well I can change ‘stable’ to point at v2.0 and the next time that the web server containers restart they will start running v2.0. I can even set the containers to operate in an auto-update mode where they will update themselves, e.g. every day, to use the latest ‘stable’ version. So when I’ve got things fully configured I can just do testing of a new version, then change stable to point at the new version and over, say, the next 24 hours all the containers will update themselves without me needing to do anything more.
Getting containerised was a lot of work, but I can now start to gain the benefits of having done it!
