This is Day 11 of Butter Days, from Naked Lounge in Chico, CA.

I have very limited time, so today I’m just going to do something as small as possible. I’m going to try to generate a rust client library and use it to send one request to AWS. That’s it.

See Day 1 of Butter Days for context on what I’m ultimately trying to build.

OpenAPI Generator

Now I’m going to back to the openapi generator to generate a rust client library.

Remember from Day 6 that this was my incantation to generate a client library for the petstore:

docker run --rm -v ${PWD}:/local/out/rust/ openapitools/openapi-generator-cli generate \
    -i \
    -g rust \
    -o /local/out/rust/generated \
    --additional-properties packageName=petstore_client --library=reqwest

Now let’s try it with the AWS Swagger Definition:

docker run --rm -v ${PWD}:/local/out/rust/ openapitools/openapi-generator-cli generate \
    -i \
    -g rust \
    -o /local/out/rust/generated \
    --additional-properties packageName=aws_iam_client --library=reqwest

Then I get this output:

Exception in thread "main" org.openapitools.codegen.SpecValidationException: There were issues with the specification. The option can be disabled via validateSpec (Maven/Gradle) or --skip-validate-spec (CLI).
 | Error count: 1, Warning count: 165
	-attribute is unexpected
	-attribute is unexpected

	at org.openapitools.codegen.config.CodegenConfigurator.toContext(
	at org.openapitools.codegen.config.CodegenConfigurator.toClientOptInput(
	at org.openapitools.codegen.OpenAPIGenerator.main(

Looks like the spec has errors. Not a huge shock. I doubt anyone has used it before. Let’s try passing --skip-validate-spec like the error message suggests.

It generates now, but I have a feeling it’s not going to work. Let’s try importing it into my top level Cargo.toml and building it:

$ cargo build
... (many, many errors) ...
error[E0369]: binary operation `!=` cannot be applied to type `models::status_type::StatusType`
  --> generated/src/models/
20 |     pub status: crate::models::StatusType,
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   = note: an implementation of `std::cmp::PartialEq` might be missing for `models::status_type::StatusType`

Well, I get a ton of errors like this! Most of them look similar though, so maybe I can actually fix this PartialEq issue and get it building.

I see that StatusType is defined like this:

#[derive(Debug, Serialize, Deserialize)]
pub enum StatusType {
    #[serde(rename = "Active")]
    #[serde(rename = "Inactive")]


From this stackoverflow post it looks like I can just add PartialEq into the derive statement and it should just work. Let’s see…

Well, I got different errors! Looks like there are many other types with that problem, so maybe I can fix them all with this change. Seems like something that might be esay to add to the generator.

Unfortunately, now I can see what looks like another problem:

fn p_ost_add_client_id_to_open_id_connect_provider(
    &self, ... UNKNOWN_BASE_TYPE: crate::models::UNKNOWN_BASE_TYPE,
    x_amz_content_sha256: &str, ...)

This doesn’t seem good, and I’m getting UNKNOWN_BASE_TYPE not found errors. It looks like the generator failed there, and I’m not sure why. I’ll have to actually look at the generator to see where the UNKNOWN_BASE_TYPE string comes from.

At first I thought it might be getting confused by the $ref keyword, but when I run curl -o - | grep "\$ref" it looks like the petstore definition has it too, and I didn’t have the same problems with that.

Next Time

I wasn’t kidding when I said I didn’t have much time today.

The next few weeks I’m going to be pretty busy preparing for Kubecon, but I’ll try to at least do something small.

From what I did today, I learned that:

  1. According to openapi-generator, the spec is invalid.
  2. The rust code generator isn’t happy with the spec.
  3. The rust code generator may need some other updates.

Given that, next time the first order of business is to try to figure out what is wrong with the spec and get it to the point where openapi-generator is happy with it. At that point, maybe I can submit a PR to the project that generated this spec and also add some more validation tests.