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Example Fn Go FDK : API Gateway

This example provides a Function to use as an API Gateway backend. The function accepts a typed request for easy object handling and returns http response.

Dependencies

  • [fn-events] for fn_events.APIGatewayHandler handlers.

Demonstrated FDK features

This example showcases how to use the fn-event APIGatewayFunction to use a Function as the backend.

Step by step

Set the API Gateway and Function backend Adding a Function in OCI Functions as an API Gateway Back End

The Function entrypoint accepts the fn_events.APIGatewayHandler handler.

func.go

package main

import (
    "context"
    "github.com/fnproject/fdk-go"
    fn_events "github.com/fnproject/fn-events"
    "net/http"
    "reflect"
)

type RequestEmployee struct {
    Name string `json:"name"`
}

type ExampleAPIGatewayHandler struct {
    employeeService EmployeeService
}

func NewApiGatewayHandler() *ExampleAPIGatewayHandler {
    return &ExampleAPIGatewayHandler{
        employeeService: &RealEmployeeService{},
    }
}

func (h *ExampleAPIGatewayHandler) Serve(ctx context.Context, requestEvent fn_events.APIGatewayRequestEvent[RequestEmployee]) *fn_events.APIGatewayResponseEvent[any] {
    requestEmployee := requestEvent.Body

    id := requestEvent.QueryParameters.Get("id")

    responseEmployee, err := h.employeeService.CreateEmployee(&requestEmployee, id)
    if err != nil {
        builder := fn_events.NewAPIGatewayResponseEventBuilder[any]()
        return builder.Body(err).StatusCode(http.StatusBadRequest).Build()
    }
    headers := fn_events.Headers{
        "X-Custom-Header":   {"HeaderValue"},
        "X-Custom-Header-2": {"HeaderValue2"},
        "Content-Type":      {"application/json"},
    }

    builder := fn_events.NewAPIGatewayResponseEventBuilder[any]()
    return builder.Body(responseEmployee).StatusCode(http.StatusCreated).Headers(headers).Build()
}

func main() {
    handler := fn_events.APIGatewayHandler(NewApiGatewayHandler(), reflect.TypeOf(RequestEmployee{}))
    fdk.Handle(handler)
}

The APIGatewayRequestEvent RequestURL is relative to the deployment path prefix see API Gateway using HTTP backend

The struct RequestEmployee is the body and Serve is always provided with the Pointer. ResponseEmployee is the response body.

To return an error response construct it.

        builder := fn_events.NewAPIGatewayResponseEventBuilder[any]()
        return builder.Body(err).StatusCode(http.StatusBadRequest).Build()