Inconsistent build packages due to the use of ubuntu:latest base image

[hassanfarid]

What happened:
In the latest beta release, we have made changes to docker image files to take ubuntu:latest ad base image.
This was initiated from #14182 and changes are merged using #17066 .

What will happen?

I think this can lead to inconsistent resultant image based on when grafana docker image is built. If in the future, ubuntu:latest moves to a newer version, this will change environment for builds.

What should happen?

It is general industry standard to use specific version label instead of label, so that the artifacts of build process are always predictable.

I suggest that we replace ubuntu:latest with ubuntu:18.04 at places that are effected by #17066 .

Environment:

• Grafana version: v6.3.0-beta1 (2019-07-10)

[xlson]

Yes, I agree. We will make that change for the stable release.

[hassanfarid]

Can I pick this up?

[marefr]

@hassanfarid sure, that would be helpful.

[torkelo]

I thought we had a PR that fixed this? But maybe confused it with another

[hassanfarid]

@torkelo - here goes the PR : #18224