Base OS change to alpine

[ghost]

Image size 602.3 MB -> 183.5 MB

[devigned]

@colemickens, @ahmetalpbalkan and @amarzavery thoughts on moving to Alpine?

[colemickens]

It seems to be the way things are moving and the image size reduction is welcome. A few random non-blocking thoughts from me:

• this moves from the LTS release of Node.js to the latest stable. Not opposed to it, but I was asked to revert a change that would have moved us off of the LTS release a while back.
• as a side note, I'm surprised that the latest nodejs LTS release (4.4) isn't available in Alpine (only 4.3 is packaged), similarly the latest stable packaged is 5.11 rather than 6.1.0.
• another option would be to use this as a base: https://github.com/mhart/alpine-node

[ahmetb]

We install other dev tools (like jq, vim, curl, git) because we always assumed that people run this container to do run azure cli as well as a few other dev tasks. Therefore the image size has never been our concern.

Also our customer/user base is mostly familiar with Ubuntu. When they type bash and get an error in alpine, I can see that will cause confusion a great deal. We have closed PRs similar to this in the past, simply because image size is not a concern for us and community can easily develop smaller ones if they like.

[robert-wallis]

That's an interesting assumption Ahmet. I would assume that people are using the CLI to write automation and not necessarily running it on their dev box. One of the main benefits of the CLI is to allow computers to do things humans could do. This is why the Azure timeout thing is such a big deal for our clients.

[ahmetb]

@robert-wallis fair point, however it's not very complicated to build a custom image on top of alpine-node image mentioned above either. This is a beauty of docker and folks can roll out their images very easily.

I will let azure-ci owners decide the fate of this pull request, as I have no data on whether CLI is used more by users or scripts. I believe cli has recently added some interactive prompts (such as telemetry collection consent) which I am not sure how it behaves in an headless (scripting) mode.