THIS PROJECT IS DEPRECATED IN FAVOR OF ITS SUCCESSOR
aws/aws-lambda-go
Author your AWS Lambda functions in Go, effectively.
AWS Lambda lets you run code without thinking about servers. For now, you can author your AWS Lambda functions, natively, in C#, Java, Node.js and Python. This project provides a native and full-featured shim for authoring your AWS Lambda functions in Go.
Table of Contents
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package main
import "github.com/eawsy/aws-lambda-go-core/service/lambda/runtime"
func Handle(evt interface{}, ctx *runtime.Context) (string, error) {
return "Hello, World!", nil
}wget -qO- https://github.com/eawsy/aws-lambda-go-shim/raw/master/src/preview.bash | bash
# "Hello, World!" executed in 0.45 ms🐣 If you like the experience, please spread the word!
| Serialization | Context | Logging | Exceptions | Environment | Events | API Gateway |
|---|---|---|---|---|---|---|
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DISCLAIMER: We do not intend to compare Go with other languages but to appreciate the overhead of our shim compared to officially supported AWS Lambda languages.
😎 It is the 2nd fastest way to run an AWS Lambda function and makes the Node.js spawn process technique obsolete.
-
Requirements
docker pull eawsy/aws-lambda-go-shim:latest go get -u -d github.com/eawsy/aws-lambda-go-core/... wget -O Makefile https://git.io/vytH8
-
Code
package main import ( "encoding/json" "github.com/eawsy/aws-lambda-go-core/service/lambda/runtime" ) func Handle(evt json.RawMessage, ctx *runtime.Context) (interface{}, error) { // ... }
-
Build
make
-
Deploy
You can use your preferred deployment method by providing it the following configuration:
- Runtime: python2.7
- Handler: handler.Handle
For example, if you deploy your function through the AWS Lambda Management Console, you will have to fill a bunch of parameters like:
Considering for example the above preview section, we have the following structure:
.
└── preview
├── handler.go
└── Makefile
The handler.go file is where resides the main entrypoint of your AWS Lambda function. There is no restriction on how
many files and dependencies you can have, nor on how you must name your files and functions. Nevertheless however we
advocate to retain the handler name and to use Handle as the name of your entrypoint.
Let's review the content of handler.go:
1 package main
2
3 import "github.com/eawsy/aws-lambda-go-core/service/lambda/runtime"
4
5 func Handle(evt interface{}, ctx *runtime.Context) (string, error) {
6 return "Hello, World!", nil
7 }
For a seamless experience we leverage Go 1.8 plugins to separate the shim from your code. At run time, AWS Lambda loads our pre-compiled shim which in turn loads your code (your plugin). A plugin is a Go main package and that is why your entrypoint must be in the main package, as seen at line 1. Notice that this restriction only applies to your entrypoint and you are free to organize the rest of your code in different packages.
While your function is executing, it can interact with AWS Lambda to get useful runtime information such as, how much
time is remaining before AWS Lambda terminates your function, the AWS request id, etc. This information is passed as the
second parameter to your function via the runtime.Context object, as seen at line 5.
With eawsy/aws-lambda-go-core we empower you with a full-featured context object to access any
available information in the exact same way that official AWS Lambda runtimes do. This is the only dependency you ever
need, as seen in line 3.
eawsy/aws-lambda-go-core dependency can be retrieved using the well known go get command:
go get -u -d github.com/eawsy/aws-lambda-go-core/...Go vendoring is also supported out of the box and behaves the same way expected when building usual go projects:
- If the
previewfolder is insideGOPATH, thenvendorfolder prevails overGOPATHdependencies. - If the
previewfolder is outsideGOPATH, thenvendorfolder is ignored in favor ofGOPATHdependencies.
5 func Handle(evt interface{}, ctx *runtime.Context) (string, error) {
6 return "Hello, World!", nil
7 }For AWS Lambda being able to call your handler, you have to make it visible outside your plugin, as seen at line 5. There is no other naming restriction but keep in mind that if you change the name of your function, you must also update it in the AWS Lambda configuration.
Tip: Use a variable to expose a handler from the inside of a package:
var Handle = mypackage.MyHandleFor the rest, the handler follows the AWS Lambda programming model by:
-
Taking 2 parameters:
- Event – Event data is automatically json unmarshalled and passed as the first argument.
You are free to use the well knownjson.RawMessagetype, any other valid Go type or even your own custom type. We also provide an extensive set of predefined event definitions if you plan to play with AWS Lambda event source mapping. - Context – Context information is passed as the second argument as explained above.
- Event – Event data is automatically json unmarshalled and passed as the first argument.
-
Returning 2 values:
- Result – The first return value is automatically json marshalled and forwarded back to the client.
You are free to use the well knowninterface{}type, any other valid Go type or even your own custom type to leverage fine grained json marshalling. - Error – The second return value notifies AWS Lambda an error occurred during execution. As expected it prevails
over the first return value. You are free to return native Go errors or custom ones:
type CustomError struct { s string } func (e *CustomError) Error() string { return e.s } func Handle(evt interface{}, ctx *runtime.Context) (interface{}, error) { return nil, &CustomError{"somthing bad happened"} }
- Result – The first return value is automatically json marshalled and forwarded back to the client.
In line with the AWS Lambda programming model, one should be able to output logs using standard abilities of the language. Your function can contain logging statements using the official Go log package and AWS Lambda writes theses logs to AWS CloudWatch Logs asynchronously. There is no restriction on how to configure or use the Go log package.
package main
import (
"log"
"github.com/eawsy/aws-lambda-go-core/service/lambda/runtime"
)
func Handle(evt interface{}, ctx *runtime.Context) (interface{}, error) {
log.Println("Hello, World!")
return nil, nil
}
In the course of a normal and controlled execution flow, you can notify AWS Lambda an error occurred by returning an
error as explained above.
In case of unexpected situations when the ordinary flow of control stops and begins panicking and if you have not any
recover mechanism in place, then the stack trace is logged in AWS CloudWatch Logs and AWS Lambda is
notified an error occurred.
We provide a Docker image based on Amazon Linux container image to build your binary in the exact same environment than AWS Lambda. This image embeds our pre-compiled shim along with helper scripts to package your function. You can use it as such or build your own custom image from it:
docker pull eawsy/aws-lambda-go-shim:latestAlthough not strictly required, we also provide an example Makefile to streamline common use cases. You are free to customize, modify and adapt it to your needs. Let's review its content briefly:
HANDLER ?= handler
PACKAGE ?= $(HANDLER)
docker:
@docker run ...
build:
@go build ...
pack:
@pack ...-
Customize – The first two environment variables allow you to customize the name of your handler and the generated package:
make . └── preview ├── handler.go ├── handler.so ├── handler.zip └── MakefileHANDLER=myhandler PACKAGE=mypackage make . └── preview ├── handler.go ├── Makefile ├── myhandler.so └── mypackage.zip -
Dockerize – The
dockertarget runs our Docker image and executes the rest of the build process inside it. -
Build – The
buildtarget builds your code with the plugin build mode. Feel free to customize build flags. -
Package – The
packtarget is by far the most important one. It packages your previously built plugin and inject our pre-compiled shim, with the correct name, into the package.
Be careful if you customize the exampleMakefileor if you build your own custom image, the way the shim is injected into the package ensures its correct functioning.
The only intent of this project is to provide the most seamless and effective way to run Go on AWS Lambda. We do not provide any sugar and you are free to use your tools of predilection for deployment with the following settings in AWS Lambda:
- Runtime:
python2.7 - Handler:
handler.Handle(unless customized as explained above)
- The behavior of the Go fmt package is non-deterministic in AWS CloudWatch Logs. Please use Go log package instead.
Even if some of these behaviors can be overcome, we mimic the official AWS Lambda runtimes.
- Log statements are not visible during initialization. If you log anything in the
initfunction, it won't be written in AWS CloudWatch Logs.
This project is maintained and funded by Alsanium, SAS.
We ❤️ AWS and open source software. See our other projects, or hire us to help you build modern applications on AWS.
We want to make it easy for you, users and contributers, to talk with us and connect with each others, to share ideas, solve problems and make help this project awesome. Here are the main channels we're running currently and we'd love to hear from you on them.
Follow and chat with us on Twitter.
Share stories!
This is for all of you. Users, developers and curious. You can find help, links, questions and answers from all the community including the core team.
Ask questions!
You are invited to contribute new features, fixes, or updates, large or small; we are always thrilled to receive pull requests, and do our best to process them as fast as we can.
Before you start to code, we recommend discussing your plans through the eawsy/bavardage channel, especially for more ambitious contributions. This gives other contributors a chance to point you in the right direction, give you feedback on your design, and help you find out if someone else is working on the same thing.
Write code!
This product is licensed to you under the Apache License, Version 2.0 (the "License"); you may not use this product except in compliance with the License. See LICENSE and NOTICE for more information.
Alsanium, eawsy, the "Created by eawsy" logo, and the "eawsy" logo are trademarks of Alsanium, SAS. or its affiliates in France and/or other countries.
Amazon Web Services, the "Powered by Amazon Web Services" logo, and AWS Lambda are trademarks of Amazon.com, Inc. or its affiliates in the United States and/or other countries.
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