Added version to docker tag #542

[eddiewebb]

This change accesses the environment variable CIRCLE_TAG to address #542

Changes:

1. Break docker push into its own job, runs only on tag creation
2. Use machine executor for docker push job (a little faster since it avoids shipping docker context around)
3. use the CIRCLE_TAG variable provided on tag builds

Options:

1. We can merge jobs back AND/OR
2. We can still publish SHA on master and just AMJOR/MINOR/PATCH, etc on tags

I ran in my own circle spae to test tagging. I obviously dont have your docker creds, so the push fails, but the tagging works.

Run:

#!/bin/bash -eo pipefail
docker tag mozilla/sops "mozilla/sops:$CIRCLE_SHA1"
# Update all semvers affected
echo "Tag mozilla/sops:$MAJOR"
docker tag mozilla/sops "mozilla/sops:$MAJOR"
echo "Tag mozilla/sops:$MAJOR.$MINOR"
docker tag mozilla/sops "mozilla/sops:$MAJOR.$MINOR"
echo "Tag mozilla/sops:$MAJOR.$MINOR.$PATCH"
docker tag mozilla/sops "mozilla/sops:$MAJOR.$MINOR.$PATCH"
docker images

Output

Tag mozilla/sops:0
Tag mozilla/sops:0.0
Tag mozilla/sops:0.0.5
REPOSITORY          TAG                                        IMAGE ID            CREATED                  SIZE
mozilla/sops        0                                          c533f52a658b        Less than a second ago   2.3GB
mozilla/sops        0.0                                        c533f52a658b        Less than a second ago   2.3GB
mozilla/sops        0.0.5                                      c533f52a658b        Less than a second ago   2.3GB
mozilla/sops        57f8a1fef66eb850dff6e43f06b1def877cff6af   c533f52a658b        Less than a second ago   2.3GB
mozilla/sops        latest                                     c533f52a658b        Less than a second ago   2.3GB
golang              1.12                                       8639ad3fc384        6 days ago               810MB

[codecov-io]

Codecov Report

Merging #607 into develop will increase coverage by 0.02%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop     #607      +/-   ##
===========================================
+ Coverage    37.11%   37.13%   +0.02%     
===========================================
  Files           21       21              
  Lines         2891     2892       +1     
===========================================
+ Hits          1073     1074       +1     
  Misses        1724     1724              
  Partials        94       94

Impacted Files	Coverage Δ
config/config.go	71.64% <0%> (+0.21%)	⬆️

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[ajvb]

Thank you for this PR @eddiewebb!

First thing, can you change this to be a PR against mozilla:develop rather than the master branch?

Second, I'm not a fan of using a semvar tool as it feels a bit heavy weight + I don't like pulling in some random code and running it. Can this be replaced with bash commands?