Go Web App

Introduction

The web application contained within this repo is used within the Optimize a Deployed AWS Web Application hands-on lab. The web application is designed to read from a configured directory the latest file written into it and return back it's contents (SHA256 string). The directory from which it reads can either be a filesystem directory or an S3 bucket.

Design

The web application is developed using Go and leverages the Echo framework.

Startup

The web application executable when started will listen on port 8080, and must be passed either the S3Bucket or FilePath environment variable, which instructs the application where to read the latest modified file from.

In the following example the web application is started up with the FilePath environment variable set to /cloudacademy/files

FilePath=/cloudacademy/files ./webapp
environemnt variable S3Bucket: 
environment variable FilePath: /cloudacademy/hashfiles

   ____    __
  / __/___/ /  ___
 / _// __/ _ \/ _ \
/___/\__/_//_/\___/ v4.6.3
High performance, minimalist Go web framework
https://echo.labstack.com
____________________________________O/_______
                                    O\
⇨ http server started on [::]:8080

Application Endpoints

The main() function within the web application sets up and configures the following routes:

func main() {
	e := echo.New()

	e.GET("/", getSHA)
	e.GET("/sha256", getSHA)
	e.GET("/thrash", thrash)
	e.GET("/version", version)
	e.GET("/ok", ok)

	e.Logger.Fatal(e.Start(":8080"))
}

• / - root path, serves up the latest SHA256 string
• /sha256 - serves up the latest SHA256 string (same as the root path)
• /thrash - used to load up the CPU, useful for causing ASG scale out events
• /version - metadata, returns versioning information
• /ok - used for health checks when configured behind a load balancer, e.g. ALB

Build

The source code can compiled using the following command:

go build -o webapp 

The following script is used to build OS specific versions of the executable:

go get -v -t -d ./...
CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o webapp
tar -czf release-${{ env.RELEASE_VERSION }}.linux-amd64.tar.gz webapp
CGO_ENABLED=0 GOOS=linux GOARCH=arm64 go build -o webapp
tar -czf release-${{ env.RELEASE_VERSION }}.linux-arm64.tar.gz webapp
CGO_ENABLED=0 GOOS=darwin GOARCH=amd64 go build -o webapp
tar -czf release-${{ env.RELEASE_VERSION }}.darwin-amd64.tar.gz webapp