[BUG] Unnecesary domain validation

[wkalbar]

Describe the bug
There is hostname_domain_extension validation set to: ^[a-zA-Z0-9.-]{0,20}$
With our domain it let us space only for 5 chars for subdomain.

How to reproduce
Steps to reproduce the behavior:

1. execute epicli init ... (with params)
2. edit config file and set hostname_domain_extension to value longer than 20 chars
3. execute epicli apply ...

Expected behavior
Change validation to at last ^[a-zA-Z0-9.-]{0,25}$. If this limitation is caused by whole VM name, please change kubernetes in VM name to k8s (kubernetes-master is the longest name in whole cluster).

Config files
n/a

Environment

• Cloud provider: Azure

epicli version: 1.0.2

Additional context
n/a

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[rafzei]

@seriva there is any requirement to have this 20chars limitation?

[przemyslavic]

@rafzei I guess it is more complex. Linux host name cannot exceed 64 characters in length.

ERROR cli.engine.terraform.TerraformCommand - Error: compute.VirtualMachinesClient#CreateOrUpdate: Failure sending request: StatusCode=400 -- Original Error: Code="InvalidParameter" Message="Linux host name cannot exceed 64 characters in length or contain the following characters: ` ~ ! @ # $ % ^ & * ( ) = + _ [ ] { } \\ | ; : ' \" , < > / ?." Target="computerName"

We allow prefix to be 2-8 characters and cluster name 3-20.
Consider the opendistro component:
prefix - cluster name - component name - vm - x
12345678-12345678901234567890-opendistro-for-elasticsearch-vm-0
It is already 63 characters long without domain extension.
It strictly depends on the chosen cluster name, prefix and components used.

Maybe it would be better to turn off the validation and then Azure API will return an error if the limit is exceeded.

[wkalbar]

Please consider change kubernetes into k8s in kubernetes node/master VM names. It'll cut 7 chars from longest names in cluster (and you can then limit component name to 15 instead of 20, and then domain name can be 25 instead 20 (for example).