g8

g8

Provides the following utilities to simplify working with AWS lambda and Api Gateway.

• Simple handler interface
• HTTP request parsing with JSON support and request body validation
• HTTP response writer with JSON support
• Custom error type with JSON support
• Logging unhandled errors with a stack trace
• Correlation ID
• New Relic integration

Request body parsing

Use the bind method to unmarshal the response body to a struct

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

handler := func(c *g8.APIGatewayProxyContext) error {
	var b requestBody
	err := c.Bind(&b)
	if err != nil {
		return err
	}

	...

	c.JSON(http.StatusOK, responseBody)
}

Request body validation

Implement the Validate method on the struct

type requestBody struct {
	Name   string `json:"name"`
	Status string `json:"status"`
}

func (b body) Validate() error {
	if b.Status == "" {
		return errors.New("status empty")
	}
	return nil
}

handler := func(c *g8.APIGatewayProxyContext) error {
	var b requestBody
	err := c.Bind(&b)
	if err != nil {
		// validation error would be returned here
		return err
	}
	
	...
	
	c.JSON(http.StatusOK, responseBody)
}

API Gateway Lambda Authorizer Handlers

You are able to define handlers for Lambda Authorizer (previously known as custom authorizers) using g8. Here is an example:

    
    handler := g8.APIGatewayCustomAuthorizerHandlerWithNewRelic(
        func(c *APIGatewayCustomAuthorizerContext) error{
            c.Response.SetPrincipalID("some-principal-ID")

            c.Response.AllowAllMethods()
            // other examples:
            // c.Response.DenyAllMethods()
            // c.Response.AllowMethod(Post, "/pets/*")
            return nil
        },
        g8.HandlerConfig{
            ...
        },
    )

    lambda.StartHandler(handler)

Response writing

There are several methods provided to simplify writing HTTP responses.

handler := func(c *g8.APIGatewayProxyContext) error {
	...
	c.JSON(http.StatusOK, responseBody)
}

Errors

Go Errors

Returning Go errors to the error response writer will log the error and respond with an internal server error

handler := func(c *g8.APIGatewayProxyContext) error {
	...
	return errors.New("something went wrong")
}

Custom Errors

You can return custom g8 errors and also map them to HTTP status codes

handler := func(c *g8.APIGatewayProxyContext) error {
	...
	return g8.Err{
		Status: http.StatusBadRequest,
		Code:   "SOME_CLIENT_ERROR",
		Detail: "Invalid param",
	}
}

Writes the the following response, with status code 400

{
  "code": "SOME_CLIENT_ERROR",
  "detail": "Invalid param"
}

Logging stack traces

Unhandled errors are logged automatically with a stack trace if the error is wrapped by eris.

eris.Wrapf(err, "failed to send offers to user id: %v", userID)