Velero panics on delete backup request when done using the API

[hmehra]

What steps did you take and what happened:
On sending a delete backup request using the API, Velero panics.
Here is the payload of the request -

{"kind":"DeleteBackupRequest","apiVersion":"velero.io/v1","metadata":{"name":"k8s-job-21","namespace":"velero"},"spec":{"backupName":"k8s-job-21"}}

What did you expect to happen:
Backup deletion is successful.

The output of the following commands will help us better understand what's going on:
(Pasting long output into a GitHub gist or other pastebin is fine.)

• kubectl logs deployment/velero -n velero
  https://pastebin.com/U6etiCQF

• velero backup describe <backupname> or kubectl get backup/<backupname> -n velero -o yaml

velero describe backup k8s-job-21
Name: k8s-job-21
Namespace: velero
Labels: velero.io/storage-location=magneto-0-1-7-ext
Annotations:

Phase: Completed

Namespaces:
Included: nginx-example
Excluded:

Resources:
Included: *
Excluded:
Cluster-scoped: excluded

Label selector:

Storage Location: magneto-0-1-7-ext

Snapshot PVs: auto

TTL: 0s

Hooks:

Backup Format Version: 1

Started: 2019-06-05 11:21:28 -0700 PDT
Completed: 2019-06-05 11:21:32 -0700 PDT

Expiration: 0001-01-01 00:00:00 +0000 UTC

Persistent Volumes:

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]
@skriss debugged the issue and determined that delete requests need to have a label else Velero panics.

Environment:

• Velero version (use velero version):
  velero version
  Client:
  Version: v1.0.0
  Git commit: 72f5cad
  Server:
  Version: v0.11.0

• Kubernetes version (use kubectl version):
  kubectl version
  Client Version: version.Info{Major:"1", Minor:"14", GitVersion:"v1.14.2", GitCommit:"66049e3b21efe110454d67df4fa62b08ea79a19b", GitTreeState:"clean", BuildDate:"2019-05-16T16:23:09Z", GoVersion:"go1.12.5", Compiler:"gc", Platform:"linux/amd64"}
  Server Version: version.Info{Major:"1", Minor:"14", GitVersion:"v1.14.1", GitCommit:"b7394102d6ef778017f2ca4046abbaa23b88c290", GitTreeState:"clean", BuildDate:"2019-04-08T17:02:58Z", GoVersion:"go1.12.1", Compiler:"gc", Platform:"linux/amd64"}

• Kubernetes installer & version:
  Minikube

• OS (e.g. from /etc/os-release):
  18.04.1-Ubuntu

[skriss]

It looks like there are various places in backup_deletion_controller.go where labels are added to the DeleteBackupRequest without first ensuring that the .Labels field is non-nil. Reads from a nil map are fine in go, but inserts to nil maps will panic.

[prydonius]

@skriss I could take a shot at this one

[skriss]

Exactly what I was thinking :)