Add example for using default env vars as docker build arg

[markphelps]

Adding example on how customers can use default env vars as build arguments

[markphelps]

Will do

[markphelps]

Actually thats not gonna work when run locally because CommitID is only populated in CI.

[mlocher]

Very valid point though having those available locally as well would be great (though a completely different topic).

[markphelps]

Thats not really possible without depending on git or mercural to be installed on the users machine as jet has no view of the commits associated with a project. In production it gets sent that information by the SCM

On Mon, Feb 12, 2018 at 8:57 AM, Marko Locher notifications@github.com wrote:

Very valid point though having those available locally as well would be great (though a completely different topic).

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[rheinwein]

@mlocher If a user wants to simulate having the commit ID available, they can populate it manually via --ci-commit-id

[markphelps]

True, but just running jet steps in the base of this project (as most users probably do) will not work since there will be no commit ID for that step

[markphelps]

We could update it to depend on the CI env var instead and do something like:

if CI {
  echo "I'm running in CI environment
} else {
  echo "I'm running locally"
}

or something to that effect