How to Build Your First Web App in Go
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The document provides an overview of building web applications in Go. It discusses how Go allows creating self-contained binaries without wrappers like Apache or Nginx. It demonstrates a simple Hello World web app in Go and shows how to use templates to render HTML. It also covers routing, middleware, sessions, deployment to Google App Engine, and examples of real web apps built and deployed with Go.
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How to Build Your First Web App in Go
- 1. Building Your First Web App in Go Andy Watson Ionic Security #ATOWebGo #ATO2015 All Things Open 2015
- 2. About Me Who: Andy Watson What: Code Flinger Where: Ionic Security http://ionic.com/ @andrewwatson
- 3. I used to write PHP Lots of PHP. Tons.
- 4. I’m a Gopher Now
- 5. Take the Tour at golang.org
- 6. Web Apps in Go • No need for a wrapper like Apache or Nginx • Create a self-contained, statically compiled binary • Cross Compile from your laptop to your server architecture
- 7. Simple Web App package main import ( "fmt" "net/http" ) func main() { http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) { fmt.Fprint(w, "Hello, worldn") }) fmt.Print("Listening on :8080n") http.ListenAndServe(":8080", nil) }
- 8. Templates Easily render well formed HTML using data from your application Nest templates inside each other (partials) for easy re-use
- 9. Simple Template Example func handleRoot(w http.ResponseWriter, req *http.Request) { var templateStr = "<html><body><h1>{{.}}</h1></body></html>n" var templ = template.Must(template.New("qr").Parse(templateStr)) templ.Execute(w, "Hello!") } func main() { http.HandleFunc("/", handleRoot) fmt.Print("Listening on :8080n") http.ListenAndServe(":8080", nil) }
- 11. Iterations type Book struct { Author, Title string } func handler(w http.ResponseWriter, r *http.Request) { // var bookList Book[] bookList, err := lookupBooksForSale() templ.Execute(w, bookList) }
- 12. Template with range Operator <h1>Books For Sale</h1> {{range .}} <h3>{{.Title}} by {{.Author}} </h3> {{else}} <h3>Sorry.</h3> {{end}}
- 13. Outputs <h3>Sorry.</h3> <h3>The Thing by Stephen King</h3> <h3>Moby Dick by Herman Melville</h3> With Empty List With Data
- 14. It’s the Methods, man! func uploadHandler(…) { if r.Method != "POST" { err := doPostThings() handleErrors(err) return } }
- 15. Routing Use a routing library like httprouter or mux to match requests to handlers Routes defined using paths and HTTP verbs r := httprouter.New() r.POST(”/login", LoginHandler) r.GET("/", HomeHandler)
- 16. MiddleWare Gets executed with every request Used for logging, instrumentation, error handling and more
- 17. Negroni func main() { mux := http.NewServeMux() mux.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) { fmt.Fprintf(w, "Welcome to the home page!") }) n := negroni.Classic() n.UseHandler(mux) n.Run(":3000") } https://github.com/codegangsta/negroni
- 18. Negroni Classic Common set of middleware • Logging • Recovery (from panics) • Static Content Handling
- 19. Render • Cleans Up boilerplate template rendering code • Handles Errors • Takes care of headers for HTML, JSON, XML etc https://github.com/unrolled/render
- 20. Context • Stores values shared during a request lifetime • Useful for easily passing the full context of a request to multiple handlers http://www.gorillatoolkit.org/pkg/context
- 21. Sessions Keep data between requests to maintain state • User information • Shopping Cart • ETC http://www.gorillatoolkit.org/pkg/sessions
- 22. Setting up Session Handling var sessionstore = sessions.NewCookieStore([]byte(secret)) func init() { sessionstore.Options = &sessions.Options{ Path: "/", MaxAge: 3600, HttpOnly: true, } }
- 23. Using Sessions session, _ := sessionstore.Get(req, "OthrNumbr-session") session.Values["loggedin"] = true session.Values["cust_id"] = cust.CustomerId session.Values["description"] = cust.Description session.Save(req, w) http.Redirect(w, req, "/home/", 302)
- 24. Rapid Development • Gin wraps your process • Recompiles and Restarts Automatically • https://github.com/codegangsta/gin
- 25. Deploy to Production • Cross Compile for Linux • SCP to production • Wrap in upstart script etc
- 26. Get up and Go
- 27. Contain Yourself The GoLang library Docker images make it easy to build and run your Go app in a container https://hub.docker.com/_/golang/
- 29. Docker Commands $ docker build -t hello-world . $ docker run --rm -it --name fred hello-world
- 30. Google App Engine • GAE supports Go runtime • Automatically scales up instances • Provides highly available datastore • Supports Go 1.4 at this time • Soon: Migrate GAE to Managed VMs https://cloud.google.com/appengine/
- 31. GAE DataStore type Greeting struct { Author string Content string Date time.Time }
- 32. Fetch from DataStore func root(w http.ResponseWriter, r *http.Request) { c := appengine.NewContext(r) q := datastore.NewQuery("Greeting"). Ancestor(guestbookKey(c)).Order("-Date").Limit(10) greetings := make([]Greeting, 0, 10) if _, err := q.GetAll(c, &greetings); err != nil { http.Error(w, err.Error(),500) return } }
- 33. GAE Example https://github.com/GoogleCloudPlatform/appen gine-guestbook-go Shows session handling, data storage, authentication and more
- 34. Other Resources Building Web Apps with Go – by codegangtsa http://bit.ly/WebAppsWithGo Google Cloud Platform - Go http://bit.ly/GoGoogleCloud
- 35. Deployed To GAE SMS Voting Application for CSS Dev Conf • Takes votes via SMS (Twilio) and stores them in GAE Datastore • Outputs them as CSV
- 36. Deployed to GAE OthrNumbr • Burner Numbers for texting with strangers • Written in Go, Deployed on App Engine • Users Datastore, memcache, Twilio, Stripe http://othrnumbr.com/
- 38. Kitty wants to learn concurrency
- 39. Concurrency in Go • In Go, concurrency is accomplished by passing shared values around on channels • Not by sharing memory between threads
- 40. Repeat After Me “Do not communicate by sharing memory; instead, share memory by communicating.”
- 41. Concurrent Routines Created by putting “go” in front of function calls func Announce(message string, delay time.Duration) { go func() { time.Sleep(delay) fmt.Println(message) }() // Note the parentheses - must call the function. } https://golang.org/doc/effective_go.html#concurrency
- 42. Channels Go has a built in primitive types for communicating between goroutines c := make(chan int) // Allocate a channel. // Start the sort in a goroutine; when it completes, signal on the channel. go func() { list.Sort() c <- 1 // Send a signal; value does not matter. }() doSomethingForAWhile() <-c // Wait for sort to finish; discard sent value.
- 43. Channels • Can be buffered or unbuffered • Can be declared to carry any other type, even channels!
- 44. Concurrency in Go The essential guides: http://bit.ly/ConcurrentGo http://bit.ly/AdvancedGoConcurrency
Editor's Notes
- Hello everyone, thank you for coming. I’m Andy Watson and I’m here to talk to you about ways to use cryptography correctly in your applications
- I’m currently a senior engineer at Ionic Security which is a data protection security company based out of Atlanta, GA I’ve been a software developer professionally since 1996 when I got my first job developing large scale, distributed systems for processing streams of data collected out of particle accelerators with some Physics professors at FSU. This was “cloud” computing before it had a name. Since then I’ve built mobile, desktop and web applications for companies like The Walt Disney World Resort, Maersk Sealand, Cox Communications, CoffeeCup Software and many many others.