Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Fix update-swagger-spec.sh to always cleanup etcd
**What this PR does / why we need it**:
This PR fixes `hack/update-swagger-spec.sh` so it always cleanup etcd and to noe leave orphaned process after its execution. This process also doesn't allow to run the script again as it detects existing etcd and won't start.
I also made a minor improvement by adding guard against an empty arguments.
**Release note**:
```release-note
NONE
```
CC @simo5
Prior this change, etcd wasn't cleaned up on my machine that lead to
orphaned etcd process after the update-swagger-spec.sh failed.
This change also adds additional improvements:
- don't kill/wait/rm when argument is empty.
- use kube::util::trap_add.
This allows us to start building real dependencies into Makefile.
Leave old hack/* scripts in place but advise to use 'make'. There are a few
rules that call things like 'go run' or 'build/*' that I left as-is for now.
Right now some of the hack/* tools use `go run` and build almost every
time. There are some which expect you to have already run `go install`.
And in all cases the pre-commit hook, which runs a full build wouldn't
want to do either, since it just built!
This creates a new hack/after-build/ directory and has the scripts which
REQUIRE that the binary already be built. It doesn't test and complain.
It just fails miserably. Users should not be in this directory. Users
should just use hack/verify-* which will just do the build and then call
the "after-build" version. The pre-commit hook or anything which KNOWS
the binaries have been built can use the fast version.
Kubernetes Submit Queue