Go Functions-as-a-Service

Running a Go application on AWS Lambda is easier than ever, once you figure out how to configure Lambda, API Gateway and 10 or other "serverless" services to support the Go functions.

This is a boilerplate app with all the AWS pieces configured correctly and explained in depth. See the docs folder for detailed guides about functions, tracing, security, automation and more with AWS and Go.

With this foundation you can skip over all the undifferentiated setup, and focus entirely on your Go code.

Motivation

Functions-as-a-Service (FaaS) like AWS Lambda are one of the latest advances in cloud Infrastructure-as-a-Service (IaaS). Go is particularly well-suited to run in Lambda due to its speed, size and cross-compiler. Check out the Intro to Go Functions-as-a-Service and Lambda doc for more explanation.

For a long time, Go in Lambda was only possible through hacks -- execution shims, 3rd party frameworks and middleware, and little dev/prod parity. But in January 2018, AWS launched official Go support for Lambda and Go released v1.10 paving the clearest path yet for us Gophers.

This project demonstrates a simple and clean foundation for Go in Lambda. You can clone and deploy it with a few commands to get a feel for the stack. Or you can fork and rework it to turn it into your own web app.

It demonstrates:

Component	Via	Config, Code
HTTP functions	Lambda, API Gateway	💾
Worker functions (one-off and periodic)	Lambda, Invoke API, CloudWatch Events	💾
Development, packaging and deployment	make, go, aws-sam-cli, CloudFormation	⚙️
Per-function environment and policies	Lambda, IAM	⚙️
Custom domains	CloudFront, ACM	⚙️
Static web content	S3, CloudFront, ACM	⚙️
Static web security with Google OAuth 2.0	CloudFront, Lambda@Edge, SSM Parameters	💾
Function security with CORS and JWT	API Gateway, jwt-go	💾
Function traces and logs	CloudWatch Logs, X-Ray, AWS SDKs for Go	💾
Notifications	SNS	💾
Databases and encryption at rest	DynamoDB, KMS	💾
Testing with mock AWS clients	Go interfaces, aws-sdk-go	💾

What's remarkable is how little work is required to get all functionality for our app. We don't need a framework, platform-as-a-service, or even any 3rd party software-as-a-service. And no, we don't need servers. By standing on the shoulders of Go and AWS, all the undifferentiated heavy lifting is managed for us.

We just need an expert CloudFormation config file and a simple Makefile, then we can focus entirely on writing Go functions.

Quick Start

This project uses :

Install the CLI tools and Docker CE

$ brew install awscli go node python@2 watchexec
$ pip2 install aws-sam-cli
$ open https://store.docker.com/search?type=edition&offering=community

We may want to double check the installed versions...

$ aws --version
aws-cli/1.14.40 Python/3.6.4 Darwin/17.4.0 botocore/1.8.44

$  -v
SAM CLI, version 0.3.0

$ docker version
Client:
 Version:	18.03.0-ce
 API version:	1.37
 Go version:	go1.9.4
 Git commit:	0520e24
 Built:	Wed Mar 21 23:06:22 2018
 OS/Arch:	darwin/amd64
 Experimental:	false
 Orchestrator:	swarm

Server:
 Engine:
  Version:	18.03.0-ce
  API version:	1.37 (minimum version 1.12)
  Go version:	go1.9.4
  Git commit:	0520e24
  Built:	Wed Mar 21 23:14:32 2018
  OS/Arch:	linux/amd64
  Experimental:	true

$ go version
go version go1.10 darwin/amd64

$ watchexec --version
watchexec 1.8.6

We may also want to configure the AWS CLI with IAM keys to develop and deploy our application...

Follow the Creating an IAM User in Your AWS Account doc to create a IAM user with programmatic access. Call the user gofaas-admin and attach the "Administrator Access" policy for now.

Then configure the CLI. Here we are creating a new profile that we can switch to with export AWS_PROFILE=gofaas. This will help us isolate our experiments from other AWS work.

Configure an AWS profile with keys and switch to the profile:

$ aws configure --profile gofaas
AWS Access Key ID [None]: AKIA................
AWS Secret Access Key [None]: PQN4CWZXXbJEgnrom2fP0Z+z................
Default region name [None]: us-east-1
Default output format [None]: json

$ export AWS_PROFILE=gofaas
$ aws iam get-user
{
    "User": {
        "Path": "/",
        "UserName": "gofaas-admin",
        "UserId": "AIDAJA44LJEOECDPZ3S5U",
        "Arn": "arn:aws:iam::572007530218:user/gofaas-admin",
        "CreateDate": "2018-02-16T16:17:24Z"
    }
}

Get the App

We start by getting and testing the github.com/nzoschke/gofaas.

$ PKG=github.com/nzoschke/gofaas
$ go get $PKG && cd $GOPATH/src/$PKG

$ make test
go get -u github.com/golang/dep/cmd/dep
dep ensure
go test -v ./...
...
ok  	github.com/nzoschke/gofaas	0.014s

This gives us confidence in our Go environment.

Develop the App

We can then build the app and start a development server:

$ make dev
cd ./handlers/dashboard && GOOS=linux go build...
2018/02/25 08:03:12 Connected to Docker 1.35
2018/02/16 07:40:32 Fetching lambci/lambda:go1.x image for go1.x runtime...

Mounting handler (go1.x) at http://127.0.0.1:3000/users/{id} [DELETE]
Mounting handler (go1.x) at http://127.0.0.1:3000/users/{id} [PUT]
Mounting handler (go1.x) at http://127.0.0.1:3000/users/{id} [GET]
Mounting handler (go1.x) at http://127.0.0.1:3000/ [GET]
Mounting handler (go1.x) at http://127.0.0.1:3000/users [POST]

Now we can access our HTTP functions on port 3000:

$ curl http://localhost:3000
<html><body><h1>gofaas dashboard</h1></body></html>

We can also invoke a function directly:

$ echo '{}' | sam local invoke WorkerFunction
...
START RequestId: 36d6d40e-0d4b-168c-63d5-76b25f543d21 Version: $LATEST
2018/02/25 16:05:21 Worker Event: {SourceIP: TimeEnd:0001-01-01 00:00:00 +0000 UTC TimeStart:0001-01-01 00:00:00 +0000 UTC}
END RequestId: 36d6d40e-0d4b-168c-63d5-76b25f543d21
REPORT RequestId: 36d6d40e-0d4b-168c-63d5-76b25f543d21  Duration: 681.67 ms  Billed Duration: 700 ms  Memory Size: 128 MB  Max Memory Used: 14 MB

Note: if you see No AWS credentials found. Missing credentials may lead to slow startup..., review aws configure list and your AWS_PROFILE env var.

This gives us confidence in our development environment.

Deploy the App

Now we can package and deploy the app:

$ make deploy
make_bucket: pkgs-572007530218-us-east-1
Uploading to 59d2ea5b6bdf38fcbcf62236f4c26f21  3018471 / 3018471.0  (100.00%)
Waiting for changeset to be created
Waiting for stack create/update to complete
Successfully created/updated stack - gofaas

ApiUrl	https://x19vpdk568.execute-api.us-east-1.amazonaws.com/Prod

Now we can access our HTTP functions on AWS:

$ curl https://x19vpdk568.execute-api.us-east-1.amazonaws.com/Prod
<html><body><h1>gofaas dashboard</h1></body></html>

We can also invoke a function directly:

$ aws lambda invoke --function-name gofaas-WorkerFunction --log-type Tail --output text --query 'LogResult' out.log | base64 -D
START RequestId: 0bb47628-1718-11e8-ad73-c58e72b8826c Version: $LATEST
2018/02/21 15:01:07 Worker Event: {SourceIP: TimeEnd:0001-01-01 00:00:00 +0000 UTC TimeStart:0001-01-01 00:00:00 +0000 UTC}
END RequestId: 0bb47628-1718-11e8-ad73-c58e72b8826c
REPORT RequestId: 0bb47628-1718-11e8-ad73-c58e72b8826c  Duration: 11.11 ms  Billed Duration: 100 ms  Memory Size: 128 MB  Max Memory Used: 41 MB

Look at that speedy 11 ms duration! Go is faster than the minimum billing duration of 100 ms.

This gives us confidence in our production environment.

Development Environment

If we want to work on the worker or database functions locally, we need to give the functions environment variables with pointers to DynamoDB, KMS and S3. Open up env.json and set BUCKET, etc. with the ids of the resources we just created on deploy:

$ aws cloudformation describe-stack-resources --output text --stack-name gofaas \
  --query 'StackResources[*].{Name:LogicalResourceId,Id:PhysicalResourceId,Type:ResourceType}' | \
  grep 'Bucket\|Key\|UsersTable'

gofaas-bucket-aykdokk6aek8            Bucket      AWS::S3::Bucket
8eb8e209-51fb-41fa-adfe-1ec401667df4  Key         AWS::KMS::Key
gofaas-UsersTable-1CYAQH3HHHRGW       UsersTable  AWS::DynamoDB::Table

Integration Testing

We can verify the app functionality by creating an isolated testing stack, testing all the endpoints, then deleting the stack. The ci.sh script automates this:

$ ./ci.sh
aws cloudformation package ...
aws cloudformation deploy ...
...
<title>My first gofaas/Vue app</title>
"username": "test"
{"ExecutedVersion":null,"FunctionError":null,"LogResult":null,"Payload":"","StatusCode":202}
...
✅ SUCCESS!

ericr3r/gofaas