[krel] Introduce krel subcommand for pushing git objects

[saschagrunert]

There are multiple issues with pushing the git references inside anago, which makes the overall process not idempotent. For example network flakes can abort the push, even if specified as dry-run. If the remote tag already exists due to another issue in anago, then we're not able to skip this step accordingly.

I would like to solve that issue inside a dedicated krel subcommand for pushing the git objects. This means that we would replace this complete part in anago:

release/anago

Lines 807 to 851 in 6e27776

	##############################################################################
	# Push git objects to github
	# NOTES:
	# * alpha is alone, pushes tags only
	# * beta is alone, pushes tags only
	# * rc is alone, pushes branch and tags
	# * official pushes both official and RC items - branch and tags
	# * New branch tags a new alpha on master, new RC on new branch and pushes
	# new branch and tags on both
	PROGSTEP[push_git_objects]="PUSH GIT OBJECTS"
	push_git_objects () {
	local b
	local dryrun_flag=" --dry-run"
	# The real deal?
	((FLAGS_nomock)) && dryrun_flag=""
	((FLAGS_yes)) \
	|| common::askyorn -e "Pausing here. Confirm push$dryrun_flag of tags" \
	"and bits" \
	|| common::exit 1 "Exiting..."
	logecho -n "Checkout master branch to push objects: "
	logrun -s git checkout master || return 1
	logecho "Pushing$dryrun_flag tags"
	for release_type in "${ORDERED_RELEASE_KEYS[@]}"; do
	logecho -n "Pushing ${RELEASE_VERSION[$release_type]} tag: "
	logrun -v -s git push $dryrun_flag origin ${RELEASE_VERSION[$release_type]} || return 1
	done
	if [[ "$RELEASE_BRANCH" =~ release- ]]; then
	logecho -n "Pushing$dryrun_flag $RELEASE_BRANCH branch: "
	logrun -v -s git push $dryrun_flag origin $RELEASE_BRANCH || return 1
	# Additionally push the parent branch if a branch of branch
	if [[ "$PARENT_BRANCH" =~ release- ]]; then
	logecho -n "Pushing$dryrun_flag $PARENT_BRANCH branch: "
	logrun -v -s git push $dryrun_flag origin $PARENT_BRANCH || return 1
	fi
	fi
	# For files created on master with new branches and
	# for $CHANGELOG_FILEPATH, update the master
	gitlib::push_master
	}

Additionally, we should enhance the implementation to:

• retry pushing on network failures
• check if the remote tag already exists and do not fail if so
• enhance testing around the common error cases

Refers to #1353
/priority important-soon

[puerco]

+1 If we are going to add more checks to the process, I think it's best to do it in go and strip anago as much as we can.

[saschagrunert]

@kubernetes/release-managers anyone wants to take this? :)

[puerco]

/assign