The dev build SDKs are not in $FLATCAR_DEV_BUILDS/sdk but published under
$FLATCAR_DEV_BUILDS/developer/sdk.
Add an environment variable to specify where the SDK is to be found
but default to $FLATCAR_DEV_BUILDS/sdk if it is not specified.
From Jenkins this variable is exported as DOWNLOAD_ROOT_SDK.
- Automated builds drop SDK and binary packages into
gs://builds.developer.core-os.net/ and the new download URL is
http://builds.developer.core-os.net/ (COREOS_DEV_BUILDS)
- Change default upload path to gs://users.developer.core-os.net/ for
misc developer builds. Official builds go elsewhere and will just be
configured in buildbot/jenkins so some COREOS_OFFICIAL stuff is gone.
- Automated builds of images go to a private bucket,
gs://builds.release.core-os.net which later gets copied to
gs://alpha.release.core-os.net and friends by core_promote.
Make it possible for other scripts to share the same value for our
release repository and equally easy to override with a custom value.
Also allow setting the root from the command line in addition to the
environment. Usually --upload_root is better to use than --upload_path.
The current logic for downloading SDK tarballs is in cros_sdk and
written in python which isn't super convenient for re-using in the rest
of our shell scripts. This is a start of rewriting that logic into a
re-usable library but does not yet replace the functionality in cros_sdk.
