Kubernetes Yaml Parser and Validating Schema

[krma...@gmail.com]

Hi All

We have a thin layer on top of Kubernetes yaml and we are using github.com/ghodss/yaml to validate it.

When i use kubectl with a k8s yaml, i see that kubectl can do a lot more validation then what is possible with a simple yaml parser like the above. For e.g. if the indentation is wrong or unrecognized element, etc.

When i use the github.com/ghodss/yaml parser, it silently drops the indentation issues and we dont get the errors untill we have converted it to kubernetes yaml and sent them to the apiserver.

From briefly looking at kubectl code, it seems like the kubectl is using swagger schema to do the validation. I am not very familiar with it.My questions are:-

- Is swagger schema validation is how kubectl is getting richer validation ?

- Is it possible to get the same level of validation with some other libraries ?

Any pointers would be helpful.

Mayank

[Brian Grant]

+SIGs CLI and API machinery

On Thu, Apr 6, 2017 at 12:28 AM, <krma...@gmail.com> wrote:

Hi All

We have a thin layer on top of Kubernetes yaml and we are using github.com/ghodss/yaml to validate it.

When i use kubectl with a k8s yaml, i see that kubectl can do a lot more validation then what is possible with a simple yaml parser like the above. For e.g. if the indentation is wrong or unrecognized element, etc.

When i use the github.com/ghodss/yaml parser, it silently drops the indentation issues and we dont get the errors untill we have converted it to kubernetes yaml and sent them to the apiserver.

From briefly looking at kubectl code, it seems like the kubectl is using swagger schema to do the validation. I am not very familiar with it.My questions are:-

- Is swagger schema validation is how kubectl is getting richer validation ?

Yes.

 

- Is it possible to get the same level of validation with some other libraries ?

You mean that you want to be able to invoke what kubectl does as a library?

I'd eventually like to see that, as well as other general-purpose kubectl functionality, and it's in the plan:

https://github.com/kubernetes/kubernetes/issues/7311

https://github.com/kubernetes/kubernetes/issues/24343

For schema validation specifically, I'd also like to see server-side support:

https://github.com/kubernetes/kubernetes/issues/12143

https://github.com/kubernetes/kubernetes/issues/5889

We also need to update the validation logic to use the newer OpenAPI spec:

https://github.com/kubernetes/kubernetes/issues/38637

 

Any pointers would be helpful.

Mayank

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[Brendan Burns]

The relevant (highly kubernetes specific) code is here:

https://github.com/kubernetes/kubernetes/tree/master/pkg/api/validation

On Thursday, April 6, 2017 at 10:28:53 AM UTC-7, Brian Grant wrote:

+SIGs CLI and API machinery

On Thu, Apr 6, 2017 at 12:28 AM, <krma...@gmail.com> wrote:

Hi All

We have a thin layer on top of Kubernetes yaml and we are using github.com/ghodss/yaml to validate it.

When i use kubectl with a k8s yaml, i see that kubectl can do a lot more validation then what is possible with a simple yaml parser like the above. For e.g. if the indentation is wrong or unrecognized element, etc.

When i use the github.com/ghodss/yaml parser, it silently drops the indentation issues and we dont get the errors untill we have converted it to kubernetes yaml and sent them to the apiserver.

From briefly looking at kubectl code, it seems like the kubectl is using swagger schema to do the validation. I am not very familiar with it.My questions are:-

- Is swagger schema validation is how kubectl is getting richer validation ?

Yes.

 

- Is it possible to get the same level of validation with some other libraries ?

You mean that you want to be able to invoke what kubectl does as a library?

I'd eventually like to see that, as well as other general-purpose kubectl functionality, and it's in the plan:

https://github.com/kubernetes/kubernetes/issues/7311

https://github.com/kubernetes/kubernetes/issues/24343

For schema validation specifically, I'd also like to see server-side support:

https://github.com/kubernetes/kubernetes/issues/12143

https://github.com/kubernetes/kubernetes/issues/5889

We also need to update the validation logic to use the newer OpenAPI spec:

https://github.com/kubernetes/kubernetes/issues/38637

 

Any pointers would be helpful.

Mayank

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[krma...@gmail.com]

Thanks Brendan and Brian for the pointers. I wanted to get the same kind of validation that kubectl offers for my own yamls which are wrappers over kubernetes yamls. It seems swagger schema is the right way to go about it.

Brian, for the issues you pointed, yes it would be indeed helpful to be able to do the same validation that kubectl does as a library. For e.g. is all the client side validation that is available in kubectl also avaialable in client-go ? That would be nice to have

-Mayank