Added example of recent CentOS termination

It was recently announced by both RedHat[1] and CentOS[2] that CentOS 8
(which was meant to end LTS at 2030) will be terminated 8 years early (by
the end of 2021). This is a perfect example of the longevity issues when
relying on third-party providers.

With this commit, I added this as a parenthesis after mentioning Ubuntu's
LTS web address. Some minor edits were also done in other parts of this
paragraph.

[1] https://www.redhat.com/en/blog/centos-stream-building-innovative-future-enterprise-linux
[2] https://blog.centos.org/2020/12/future-is-centos-stream

1 files changed, 7 insertions, 6 deletions

diff --git a/paper.tex b/paper.tex
index 13fac35..6b9bf31 100644
--- a/paper.tex
+++ b/paper.tex
@@ -158,17 +158,18 @@ We will thus focus on Docker here.
 However, that is rarely done.}
 Usually images are imported with generic operating system (OS) names; e.g., \cite{mesnard20} uses `\inlinecode{FROM ubuntu:16.04}'
   \ifdefined\noappendix
-  \new{(more examples in the \href{https://doi.org/10.5281/zenodo.\projectzenodoid}{appendices})}.%
+  \new{(more examples in the \href{https://doi.org/10.5281/zenodo.\projectzenodoid}{appendices})}%
   \else%
-  \new{(more examples: see the appendices (\ref{appendix:existingtools})).}%
+  \new{(more examples: see the appendices (\ref{appendix:existingtools}))}%
   \fi%
-The extracted tarball (from \url{https://partner-images.canonical.com/core/xenial}) is updated almost monthly, and only the most recent five are archived there.
-Hence, if the image is built in different months, its output image will contain different OS components.
-In the year 2024, when long-term support for this version of Ubuntu expires, the image will be unavailable at the expected URL.
+. The extracted tarball (from \url{https://partner-images.canonical.com/core/xenial}) is updated almost monthly, and only the most recent five are archived there.
+  Hence, if the image is built in different months, its output image will contain different OS components.
+% CentOS announcement: https://blog.centos.org/2020/12/future-is-centos-stream
+In the year 2024, when long-term support (LTS) for this version of Ubuntu expires, the image will be unavailable at the expected URL \new{(if not abruptly aborted ealier, like CentOS 8 which will be terminated 8 years early).}
 Generally, \new{pre-built} binary files (like Docker images) are large and expensive to maintain and archive.
 %% This URL: https://www.docker.com/blog/docker-hub-image-retention-policy-delayed-and-subscription-updates}
 \new{Because of this, DockerHub (where many reproducible workflows are archived) announced that inactive images (older than 6 months) will be deleted in free accounts from mid 2021.}
-Furthermore, Docker requires root permissions, and only supports recent (``long-term-support'') versions of the host kernel, so older Docker images may not be executable \new{(their longevity is determined by the host kernel, typically a decade)}.
+Furthermore, Docker requires root permissions, and only supports recent (LTS) versions of the host kernel: older Docker images may not be executable \new{(their longevity is determined by the host kernel, typically a decade).}
 
 Once the host OS is ready, PMs are used to install the software or environment.
 Usually the OS's PM, such as `\inlinecode{apt}' or `\inlinecode{yum}', is used first and higher-level software are built with generic PMs.