Update strategy for publishing images

[izgeri]

Motivation

At current, we publish 1.14-latest and latest tags for the RH UBI-based Nginx image. RH requires images use a "good tag", however, and these don't work:

8. Image should include a tag, other than latest

Test name: good_tags
Why? So the image can be uniquely identified
How? Use the docker tag command to add a tag. A common tag is the image version. The latest tag will be automatically added to the most recent image, so it should not be set explicitly.

Proposed Implementation

We are going to move to versioning this project and publishing public images only on new tags / project releases.

To accomplish this, we will:

• Add a VERSION file to the project
• Set the initial VERSION to 1.0.0
• Update the pipeline so that on pipeline builds, images are only published to the internal Docker registry
• Update the pipeline so that on v1.x.y tags, the following image tags are published to DockerHub: latest, 1, 1.x, 1.x.y. This will also involve removing the PUBLISH_DOCKERHUB build param, which will no longer be needed.
• Once these changes are merged, we'll tag 1.0.0 and publish the new images.
• Update the Conjur project to use the 1.x.y tag to build Conjur.

AC:

• Determine a strategy for adding unique tags for images (potentially don't push on every nightly build)
• Implement the new strategy for publishing images

[izgeri]

Note: the build is also broken on this issue, as RH container registry only allows you to push each tag once. It's now failing on the error:

denied: The image tag you are pushing already exists. Please re-tag the image.