[BuildStream] Fwd: Buildstream shell et al

[Sam Thursfield <ssssam gmail com>]

[forwarding to buildstream-list -- I accidentally sent this just to Sander. Apologies for the messed up formatting]

On Tue, Aug 14, 2018 at 7:54 PM Sam Thursfield <ssssam gmail com> wrote:

On Tue, Aug 14, 2018 at 2:40 PM Sander Striker via BuildStream-list <buildstream-list gnome org> wrote:

What you propose above is not much better than having to figure out how to make my tools available through .bsts, as I now need to figure out how to construct an overlay tarball.

Compare that to the creation of a new Dockerfile:

  FROM bst_elementname_key

  # I know our base system is fedora, so just yum install

  yum install SwankyDebug

That is a very low barrier to entry, where there is very little to no education to be done.  It would however make an abstraction leaky.  From the users perspective, not a tough call.  From the BuildStream developer perspective, it's much harder.

Docker can import and export in tar format. BuildStream can (I think) export in .tar format now, and Tristan's proposed additions to `bst shell` would allow you to import a .tar into the shell environment too.

So it shouldn't be too hard to get the benefits of Docker without baking it into BuildStream's core; the project just needs to provide some kind of script that exports an element, runs the given commands, and gives you an overlay ready for the developer to use.

If you want Dockerfile-like syntax, https://github.com/projectatomic/buildah might be worth a look too -- it appears to provide similar facilities to `docker build` but in a way that is much more composable with other tools.

Sam