Can't generate experimental HTTPRoute with Gateway API v1.3.0

[shaneutt]

While updating gateway-api-rs for Gateway API v1.3.0, I found that the experimental version of HTTPRoute can not be generated:

Error: not handling non-string/int enum outside oneOf block

With CORS support in Gateway API, a new field called TrueField was added:

// TrueField is a boolean value that can only be set to true
//
// +kubebuilder:validation:Enum=true
type TrueField bool

This is used here:

	// AllowCredentials indicates whether the actual cross-origin request allows
	// to include credentials.
	//
	// The only valid value for the `Access-Control-Allow-Credentials` response
	// header is true (case-sensitive).
	//
	// If the credentials are not allowed in cross-origin requests, the gateway
	// will omit the header `Access-Control-Allow-Credentials` entirely rather
	// than setting its value to false.
	//
	// Support: Extended
	//
	// +optional
	AllowCredentials TrueField `json:"allowCredentials,omitempty"`

This TrueField results in an enum which ultimately kopium doesn't currently handle:

properties:
  cors:
    description: |-
      CORS defines a schema for a filter that responds to the
      cross-origin request based on HTTP response header.

      Support: Extended
    properties:
      allowCredentials:
        description: |-
          AllowCredentials indicates whether the actual cross-origin request allows
          to include credentials.
          The only valid value for the `Access-Control-Allow-Credentials` response
          header is true (case-sensitive).
          If the credentials are not allowed in cross-origin requests, the gateway
          will omit the header `Access-Control-Allow-Credentials` entirely rather
          than setting its value to false.

          Support: Extended
        enum:
        - true
        type: boolean

[shaneutt]

@clux this one doesn't need action on your part, but I thought you mind find it interesting. 😂

I can work around the issue with the following patch:

diff --git a/src/analyzer.rs b/src/analyzer.rs
index b379320..e2ca0ca 100644
--- a/src/analyzer.rs
+++ b/src/analyzer.rs
@@ -206,6 +206,7 @@ fn analyze_enum_properties(
                 }
                 val.to_string()
             }
+            serde_json::Value::Bool(boolean) => boolean.to_string(),
             _ => bail!("not handling non-string/int enum outside oneOf block"),
         };
         let rust_type = "".to_string();

That will get kopium generation to "work" and emit:

/// AllowCredentials indicates whether the actual cross-origin request allows
/// to include credentials.
///
/// The only valid value for the `Access-Control-Allow-Credentials` response
/// header is true (case-sensitive).
///
/// If the credentials are not allowed in cross-origin requests, the gateway
/// will omit the header `Access-Control-Allow-Credentials` entirely rather
/// than setting its value to false.
///
/// Support: Extended
#[serde(
    default,
    skip_serializing_if = "Option::is_none",
    rename = "allowCredentials"
)]
pub allow_credentials: Option<bool>,

and

/// CORS defines a schema for a filter that responds to the
/// cross-origin request based on HTTP response header.
///
/// Support: Extended
#[derive(Serialize, Deserialize, Clone, Debug, JsonSchema, PartialEq)]
pub enum HTTPRouteRulesBackendRefsFiltersCorsAllowCredentials {
    #[serde(rename = "true")]
    True,
}

Which kind of works, but isn't quite right as ideally the type would be emitted as Option<HTTPRouteRulesBackendRefsFiltersCorsAllowCredentials> instead of Option<bool>? 🤔

That said, I'm not just considering what it would take to make this work in kopium, but I'm also considering changing it in Gateway API itself. The OpenAPI spec includes this:

        enum:
        - true
        type: boolean

Which feels a bit odd. The reason it is that way is because the header it represents works the same way and only allows "true" or not being set at all, so it that's how we got here. I'm thinking the fix could be to change it away from a boolean type enum in Gateway API. In fact. Interestingly I found the proposal still calls for a string:

// AllowCredentialsType describes valid value of config `AllowCredentials`.
//
// +kubebuilder:validation:Enum=true
type AllowCredentialsType string

const (
    // The actual cross-origin request allows to include credentials.
    AllowCredentials AllowCredentialsType = "true"
)

https://github.com/kubernetes-sigs/gateway-api/blob/c3dd6c38f7c798aeb6ac0525a2189c10ac2e75a8/geps/gep-1767/index.md?plain=1#L135

So it appears the current spec deviates from the proposal, but the history there is that string is considered to be a slightly worse experience for users of the field. I think the correct immediate fix is to move this away from bool in the Gateway API spec in some way.

[shaneutt]

Created kubernetes-sigs/gateway-api#3841 to start the conversation in Gateway API.