RESTful API Development using Go

RESTful API Development using Go
Baiju Muthukadan
@nogenerics
Baiju Muthukadan RESTful API Development using Go @nogenerics 1 / 30

About Me
Senior Software Engineer, Red Hat
1
https://golang.muthukadan.net

About Me
FOSS Contributor (SMC, Koha, Zope, SaltStack, fabric8 etc.)
1

About Me
Founded the Swathanthra Malayalam Computing (SMC) project in 2001
while studying at REC Calicut (NIT Kozhikode)
1

About Me
Received the ﬁrst Kenneth Gonsalves Award for contributions to the
Python community in India
1

About Me
Received the ﬁrst Kenneth Gonsalves Award for contributions to the
Python community in India
Author of the book: A Comprehensive Guide to Go Programming 1
1

Quick introduction to Go
General Purpose Programming Language

Free/Open Source

Free/Open Source
Created at Google by Robert Griesemer, Rob Pike and Ken Thompson

Free/Open Source
Development started in 2007 and publicly released in November 2009

Free/Open Source
C like syntax (no semicolons)

Free/Open Source
Object Oriented (Composition over inheritance no classes!)

Free/Open Source
Compiled (Statically linked)

Free/Open Source
Garbage collected

Free/Open Source
Garbage collected
Statically typed

Free/Open Source
Garbage collected
Statically typed
Strongly typed

Quick introduction to Go ...
built-in concurrency

Two major compilers: gc & gccgo

25 keywords (less than C,C++,Python etc.)

Classiﬁcation (Capitalized are exported public)

Fast build (in seconds)

Unused imports and variables raise compile error

Operating Systems: Windows, GNU/Linux, Mac OS X, *BSD etc.

CPU Architectures: amd64, 386, arm etc.

Cross compilation

Cross compilation
Standard library

Cross compilation
Standard library
No exceptions (Errors are values)

Cross compilation
Standard library
No exceptions (Errors are values)
Pointers (No pointer arithmetic!)

Basic example
package main
import "net/http"
func main() {
http.ListenAndServe(":8080", nil)
}

Serve content example
package main
import "net/http"
func homeHandler(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("Hello World!"))
}
func main() {
http.HandleFunc("/", homeHandler)
}

Gorilla Mux
URL router and dispatcher
http://www.gorillatoolkit.org/pkg/mux
https://github.com/gorilla/mux
go get -u github.com/gorilla/mux

Gorilla Mux Example
package main
import (
"net/http"
"github.com/gorilla/mux"
)
func homeHandler(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("Hello World!n"))
}
func main() {
r := mux.NewRouter()
r.HandleFunc("/", homeHandler).Methods("GET")
http.Handle("/", r)
}

Negroni Example
func main() {
r.HandleFunc("/", homeHandler)
n := negroni.New()
n.UseHandler(r)
http.ListenAndServe(":8080", n)
}

Negroni Middleware
An exaple from
https://github.com/kaaryasthan/kaaryasthan/blob/master/route/route.go
n = negroni.New(negroni.NewRecovery(),
negroni.NewLogger(),
negroni.NewStatic(web.AssetFS()))
n.Use(middleware)
Middlewares: gzip, jwt, cors, csp

Paths with variable
r.HandleFunc("/products/{key}", ProductHandler)
r.HandleFunc("/articles/{category}/", ArticlesCategoryHandler)
r.HandleFunc("/articles/{category}/{id:[0-9]+}", ArticleHandler)
Format: {name} or {name:pattern}

Frameworks
https://gobuffalo.io
https://goa.design
https://gin-gonic.github.io/gin
https://beego.me
https://awesome-go.com/#web-frameworks

RESTful
stateless
unique identiﬁcation of resources through URIs
standard HTTP methods (POST, GET, PATCH, DELETE)
HTTP status codes

Why RESTful?
easy to understand & document
works on limited bandwidth
READs can be cached and hence reduces the bandwidth

Architecture constraints
uniform interface
client-server
stateless
Cache-able
Layered system

REST Style consists of ...
Resources
Verbs
Media types
Status codes

Media types
Use JSON ( http://json.org )
or better JSON API SPEC ( http://jsonapi.org )
application/vnd.api+json

Authentication
Use JWT: https://jwt.io

Security
All attacks possible with web are applicable to REST API.
https://www.owasp.org
- Use TLS always

Tooling
cURL is your friend!

HTTP Methods
POST - Create
GET - Read
PATCH - Update
DELETE - Delete

An example API end points
Create item - POST /items
Read a single item - GET /items/1
Read all items - GET /items
Update item - PATCH /items/1
Delete item - DELETE /items/1

API versioning
/api/v1/items
/api/v2/items

jsonapi.org
standard for representation of JSON responses
shared convention increase productivity through generalized tooling

resource representation in JSON
{
"links": {
"self": "http://example.com/articles",
"next": "http://example.com/articles?page[offset]=2",
"last": "http://example.com/articles?page[offset]=10"
},
"data": [{
"type": "articles",
"id": "1",
"attributes": {
"title": "JSON API paints my bikeshed!"
},
"relationships": {
"author": {
"links": {
"self": "http://example.com/articles/1/relationships/author",
"related": "http://example.com/articles/1/author"
},
"data": { "type": "people", "id": "9" }
},
...

HTTP Status codes and Location header
If a POST request did not include a Client-Generated ID and the requested
resource has been created successfully, the server MUST return a 201
Created status code.
The response SHOULD include a Location header identifying the location of
the newly created resource.

structure for errors
HTTP/1.1 422 Unprocessable Entity
Content-Type: application/vnd.api+json
{
"errors": [
{
"status": "422",
"source": { "pointer": "/data/attributes/first-name" },
"title": "Invalid Attribute",
"detail": "First name must contain at least three characters."
}
]
}

Conclusion
Go is a great choice for RESTful API development

Thank You!
@nogenerics

RESTful API Development using Go

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