YDBOPS-10613 Dynconfigs

[elabpro]

Support for dynconfig
Config.yaml as a template
Fix problem with PDIsks

[blinkov]

Let's drop this setting because it'd limit the evolution of how all this is implemented under the hood. For instance, you don't really need a template here, you could just have the same object constructed in memory and then serialized to yaml. Otherwise, LGTM.

[elabpro]

It's designed to have possibility to adjust dynamic config for user needs until we have possibility to change all setting by ansible. Right not we do not provide a way to define labels or other requirements for dynamic nodes. IMHO it will be required by users for there production needs. That's why I think we must let them define their own config.

[blinkov]

Maybe it's time to introduce the concept of playbook feature flags. I don't think we'd want to keep this setting around long-term: it's more like to test this new approach, make it default at some point and then deprecate the current approach. So it could be like this:

Suggested change

	# ydb_use_dynamic_config - define how to configure dynamic nodes - static or dynamic configs
	# Default value: false
	ydb_use_dynamic_config: false
	ydb_ansible_feature_flags:
	use_dynamic_config: false

[elabpro]

It's good idea for single roles, but we might have problems in our structure
playbook1 (feature_flag: feature1, feature3) -> role1 (feature_flag: feature1)
playbook1 (feature_flag: feature1, feature3) -> role2 (feature_flag: feature1, feature2)
in this case role2 will lost feature2 default value

TASK [role1 : Output] *****************************************************************************************************************************************************************************************************
ok: [localhost] => {
    "feature_flags": {
        "feature1": true,
        "feature3": true
    }
}

TASK [role2 : Output] *****************************************************************************************************************************************************************************************************
ok: [localhost] => {
    "feature_flags": {
        "feature1": true,
        "feature3": true
    }
}