Add support to pass --ssh flag to the build

[jesserockz]

Closes #39

[codecov-commenter]

Codecov Report

Merging #123 into master will decrease coverage by 0.82%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master     #123      +/-   ##
==========================================
- Coverage   44.85%   44.03%   -0.83%     
==========================================
  Files           3        3              
  Lines         107      109       +2     
  Branches       17       17              
==========================================
  Hits           48       48              
- Misses         46       48       +2     
  Partials       13       13              

Impacted Files	Coverage Δ
src/context.ts	27.27% <0.00%> (-0.86%)	⬇️

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[tonistiigi]

Not sure if something like ssh agent socket makes sense in GH actions context. Maybe this should just take direct ssh key value from secrets and create a temp file to expose via --ssh.

[jesserockz]

That seems like it might be overcomplicating it and moving the action ssh key away from what the actual --ssh flag does.
I start up an ssh agent with a key from a secret and forward that through with this method.
The user would also be able to write the key to a file and expose that file themselves using this, if they choose to do it that way.

[tonistiigi]

Sorry, I forgot this issue. I'm fine with this approach but looks like PR needs a rebase.

[crazy-max]

@jesserockz Need rebase like @tonistiigi said and you also need to run a pre-checkin. See https://github.com/docker/build-push-action/blob/master/.github/CONTRIBUTING.md#submitting-a-pull-request

[jesserockz]

Thanks guys. I will take a look at rebasing again on Monday as I merged master on Friday and it broke our deployments.

[jesserockz]

I have rebased locally, but just waiting on a PR merge in our repo before I can push to the branch so it shows up here.

[crazy-max]

LGTM

[jesserockz]

Thanks for merging. Any chance of a new tag/release so I can update our workflows? @crazy-max @tonistiigi

[crazy-max]

@jesserockz A new release will be created tomorrow.