Callbacks

About

Callbacks are Go functions that can be provided within a Docker image, allowing request and response contents to be modified on the fly.

Signature

Request callback function signature:

func PetstoreBefore(resource string, request *http.Request) (*http.Request, error) {
    return request, nil
}

Response callback function signature:

func PetstoreAfter(reqResource *connexions_plugin.RequestedResource) ([]byte, error) {
    log.Printf("[PetstoreAfter] req path: %s\n", reqResource.URL.String())
    switch reqResource.Method {
    case http.MethodGet:
        switch reqResource.Resource {
        case "/pets":
            pets := []map[string]any{
                {"name": "dog", "id": 1, "tag": "pet"},
                {"name": "cat", "id": 2, "tag": "pet"},
            }
            log.Println("[PetstoreAfter] returning modified pets")
            return json.Marshal(pets)
        }
    }
    return reqResource.Response.Data, nil
}

connexions_plugin package is a small package that provides typing support for the callback functions.
User provided functions are built into go plugin and loaded at runtime.

Callbacks location

Functions should be placed in the callbacks directory inside the mapped data directory.
Filenames are completely arbitrary and can be named as you wish.
But the names of the functions should be:
- unique - start with UpperCase - specified in the service configuration:

Other conditions:
- Package name should be main. - Go version should exactly match the version used to build the Connexions image.

services:
  petstore:
    requestTransformer: PetstoreBefore
    responseTransformer: PetstoreAfter

callbacks directory can be any go.mod package which should compile into a shared go plugin.