gcf_go_image_resizer

README

Go Image Resizer Cloud Function

Pure Go Image Resizer function, deployable to Google Cloud Functions, using the disintegration/imaging package

Medium article: Image Resizing with Go and Cloud Functions

Original gopher image:

Resized gopher image:

Example gopher image generated using gopherize.me

Usage

https://{gcf-endpoint}/ResizeImage?url={url}&height={height}&width={width}

• url: url of the image to resize
• height: height of the output image in pixels
• width: width of the output image in pixels

if width or height is missing, the aspect ratio is preserved

Deploying

$ gcloud functions deploy ResizeImage --runtime go111 --trigger-http

Local testing

There is an http server included in cmd/server.go allowing you to test locally

$ export GO111MODULE=on
$ go get -u
$ go run cmd/server/server.go

Todo

• Add tests
• Cache input images
• Cache output images

Documentation

Index

• func EncodeImageToJpg(img *image.Image) (*bytes.Buffer, error)
• func FetchAndResizeImage(p *ResizerParams) (*image.Image, error)
• func ResizeImage(w http.ResponseWriter, r *http.Request)
• type ResizerParams
  • func NewResizerParams(url string, height int, width int) ResizerParams
  • func ParseQuery(r *http.Request) (*ResizerParams, error)

Functions

func EncodeImageToJpg

func EncodeImageToJpg(img *image.Image) (*bytes.Buffer, error)

encode image to jpeg

func FetchAndResizeImage

func FetchAndResizeImage(p *ResizerParams) (*image.Image, error)

fetch the image from provided url and resize it

func ResizeImage

func ResizeImage(w http.ResponseWriter, r *http.Request)

Cloud Function entry point

Types

type ResizerParams

type ResizerParams struct {
	// contains filtered or unexported fields
}

struct containing the initial query params

func NewResizerParams

func NewResizerParams(url string, height int, width int) ResizerParams

ResizerParams factory

func ParseQuery

func ParseQuery(r *http.Request) (*ResizerParams, error)

parse/validate the url params