The Road to OCIv2 Images: What's Wrong with Tar?
My first instinct was to title this article “Tar Considered Harmful”, but I had a feeling that the peanut gallery would cringe at such a title. However, this article is very much a foundational discussion of tar and how it fundamentally fails in the use-case of container images (which will outline what we really want from a container image format). There have been some other articles that touch on the issues I go over here, but I hope I can provide a more cohesive insight into the issues with tar. Then again, some folks believe that tar is the best format for container images. I hope this first article will serve as a decent rebuttal.
Now, don’t misunderstand what I’m saying – my point here is not “it’s old, so it’s bad.” tar is the obvious choice for an archive format, due to its long history and ubiquity, and writing a custom format with no justification would be a borderline reckless thing to do. However, tar‘s history is important to understanding how it got to the state it’s in today. This section will be quite long-winded (there’s forty-something years of history to distil into a single blog post), but you can skip to the end.