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Friday, September 7, 2018

Administration: Fourmilab Server Updated to AWS Linux 2

Since January 10, 2016, the www.fourmilab.ch site has been hosted on Amazon Web Services (AWS), using the AWS Linux machine image (AMI) as its underlying platform. This is a Linux system (very similar to the CentOS distribution) which is maintained by Amazon Web Services to provide a continuous stream of updates which avoid having to frequently re-install new releases of the system.

In June 2018 AWS announced the first major update to the Linux AMI, called Linux 2. This release is a discontinuous change and cannot be upgraded directly from the original Linux AMI—one must start with a clean installation and re-install all site-specific programs and data. Once this process is completed, AWS promises that no further re-installations will be required for the next five years.

Because the Fourmilab site is relatively complicated and has a substantial amount of custom software used to implement the various Web services available here, the migration process, although working for static documents the first day, took two months (among many other distractions) to complete and test. At 11:26 UTC on 2018-09-07 the new system went into production on the Fourmilab site. Since then, only one problem has been encountered (display of page visit counters on a few pages), which was due to a library incompatibility and has now been fixed.

This update consists entirely of changes to the software platform (operating system, compilers, libraries, scripting languages, database systems, Web server, etc.) upon which the site is built, so no changes should be apparent to visitors to the site. If you use something at the site and find that it stopped working around the time the update was installed, that's what the “Feedback” button is for.

Posted at September 7, 2018 22:03