Bastions: Remove additionalUserData

[nvanheuverzwijn]

1. What kops version are you running? The command kops version, will display
this information.
1.15.0

2. What Kubernetes version are you running? kubectl version will print the
version if a cluster is running or provide the Kubernetes version specified as
a kops flag.
1.15.6

3. What cloud provider are you using?
AWS

4. What commands did you run? What is the simplest way to reproduce this issue?
run kubectl edit ig bastions
add this to the template :

  additionalUserData:
  - content: |
      #!/bin/sh
      echo "Hello World.  The time is now $(date -R)!" | tee /root/output.txt
    name: myscript.sh
    type: text/x-shellscript 

kubectl update cluster
kubectl update cluster --yes
kubectl edit ig bastions
remove the additionalUserData
kubectl update cluster

5. What happened after the commands executed?
additionalUserdata is not removed

6. What did you expect to happen?
additionalUserdata to be removed

7. Please provide your cluster manifest. Execute
kops get --name my.example.com -o yaml to display your cluster manifest.
You may want to remove your cluster name and other sensitive information.
N/A

8. Please run the commands with most verbose logging by adding the -v 10 flag.
Paste the logs into this report, or in a gist and provide the gist link here.
N/A

9. Anything else do we need to know?