Aks-engine: kubeconfig file on jumpbox is broken

[mfabiani-av]

Describe the bug
The kubeconfig on the jumpbox is broken: it contains "\n" wherever there should be a new line, and all the ' " ' characters are escaped:

{\n \"apiVersion\": \"v1\",\n \"clusters\": [\n {\n \"cluster\": {\n \"certificate-authority-data\": ...

Steps To Reproduce
Create a cluster with this configuration:
``` "privateCluster":
{
"enabled": true,
"jumpboxProfile":
{
"name": "internalappsjump",
"vmSize": "Standard_D2_v3",
"publicKey": "ssh-rsa ..........",
"username": "xxxxxxx"
}
},

NOTE: I'm running aks-engine in Windows Linux Subsystem (Ubuntu)

**Expected behavior**
```{
     "apiVersion": "v1",
     "clusters": [
                        {"cluster": {
                              "certificate-authority-data": ...

AKS Engine version
$ aks-engine version Version: v0.36.5 GitCommit: 6b8255b54 GitTreeState: dirty

Kubernetes version
1.12.8

Additional context

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[CecileRobertMichon]

@mfabiani-av thanks for reporting, sounds like a recent regression. I've labeled this as good first issue since it should be an easy one to repro + fix. If anyone wants to pick this up and needs guidance feel free to @ me in a comment.

[Alwandy]

@CecileRobertMichon I'll pick it up since I need to use jump box myself too.. I'll fork and work my way through or any tips?

[CecileRobertMichon]

@Alwandy thanks! I would start by trying to repro to confirm the bug. Then, you will probably want to start by looking at https://github.com/Azure/aks-engine/blob/master/parts/k8s/kubeconfig.json and https://github.com/Azure/aks-engine/blob/master/parts/k8s/cloud-init/jumpboxcustomdata.yml#L16.

[Alwandy]

I successfully reproduced the issue.

Will investigate on a fix now.

[mfabiani-av]

Hello,
has this fix made it to the latest versions? I'm running Version: v0.38.4 but still have the same problem.

[CecileRobertMichon]

@mfabiani-av not yet, https://github.com/Azure/aks-engine/commit/86030eb128ac6528674f7ca69f5d083f0b99f677 isn't included in v0.38. It will be included in the upcoming v0.39.0.