invoker

README

lambda-invoker

Lightweight library to simplify invoking a lambda function.

Usage

Initialze an Invoker, passing it a lambda.Service and the arn of the lambda function being invoked. Then invoke the function passing it your json request.

invoker := New(svc, "function-arn")
rsp, err := invoker.Invoke(ctx, []byte(`{"request":"content"}`))
// Do something with output.

Router

It's likely you'll want to use the invoker with 'edstell/lambda-router'; an Option has been included with this package to make this easy. Initialize a new Invoker, passing it the 'AsProcedure' option. AsProcedure takes a procedure name which instructs the invoked function which handler to route this request to, and an 'unmarshalError' func - which will be used when unmarshaling a returned error. This allows you to define your own custom error implementations and pass them between lambda functions. You'll need to initialize a new Invoker for each procedure you intend to call.

invoker := New(svc, "function-arn", AsProcedure("On", unmarshalErrorFunc))
rsp, err := invoker.Invoke(ctx, []byte(`{"request":"content"}`))

Documentation

Index

• type Error
• type Invoker
  • func New(li LambdaInvoker, arn string, opts ...Option) *Invoker
  • func (i *Invoker) Invoke(ctx context.Context, body json.RawMessage, opts ...awsreq.Option) (json.RawMessage, error)
• type LambdaInvoker
• type Option
  • func AsProcedure(procedure string, unmarshalError func(json.RawMessage) error) Option

Types

type Error

type Error struct {
	StatusCode int64
	// contains filtered or unexported fields
}

Error wraps an error message with a status code.

type Invoker

type Invoker struct {
	MutateInput  func(*lambda.InvokeInput) error
	MutateOutput func(*lambda.InvokeOutput) error
	// contains filtered or unexported fields
}

Invoker is a wrapper around the aws lambda invoker implementation. It provides a convenient layer for middleware, as well as exposing a simpler method to invoke a lambda function with.

func New

func New(li LambdaInvoker, arn string, opts ...Option) *Invoker

New initializes an Invoker with the options passed.

func (*Invoker) Invoke

func (i *Invoker) Invoke(ctx context.Context, body json.RawMessage, opts ...awsreq.Option) (json.RawMessage, error)

Invoke _invokes_ the lambda function passing body as the InvokeInput.Payload and returning the InvokeOutput.Payload as the result. If InvokeOutput contains a FunctionError an Error is returned, wrapping the status code. By default lambda functions are invoked as a 'RequestResponse', but input mutators can be passed to change the InvocationType.

type LambdaInvoker

type LambdaInvoker interface {
	InvokeWithContext(context.Context, *lambda.InvokeInput, ...awsreq.Option) (*lambda.InvokeOutput, error)
}

LambdaInvoker abstracts the logic of invoking a lambda function behind an interface, this is to allow mocking the aws Lambda implementation.

type Option

type Option func(*Invoker)

Option implementations can mutate the Invoker allowing configuration of how invokations of a lambda function should be performed.

func AsProcedure

func AsProcedure(procedure string, unmarshalError func(json.RawMessage) error) Option

AsProcedure returns an option which can be passed when initializing an Invoker. If provided it will configure invocation to be performed as a call to the named procedure.