How to Build an Image Processing Service in Go

Build an image processing service in Go by creating an HTTP server that accepts image uploads, processes them using the image package, and returns the result.

package main

import (
	"image"
	"image/jpeg"
	"io"
	"net/http"
	"os"
)

func processImage(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}
	file, _, err := r.FormFile("image")
	if err != nil {
		http.Error(w, "Upload failed", http.StatusBadRequest)
		return
	}
	defer file.Close()
	img, _, err := image.Decode(file)
	if err != nil {
		http.Error(w, "Decode failed", http.StatusBadRequest)
		return
	}
	out, err := os.CreateTemp("", "processed-*")
	if err != nil {
		http.Error(w, "Temp file failed", http.StatusInternalServerError)
		return
	}
	defer os.Remove(out.Name())
	if err := jpeg.Encode(out, img, nil); err != nil {
		http.Error(w, "Encode failed", http.StatusInternalServerError)
		return
	}
	out.Seek(0, io.SeekStart)
	http.ServeFile(w, r, out.Name())
}

func main() {
	http.HandleFunc("/process", processImage)
	http.ListenAndServe(":8080", nil)
}

Building an image processing service in Go creates a web server that waits for users to send an image file. When a file arrives, the program reads it, converts it into a standard format, and sends the new version back to the user. It works like a digital photo booth that instantly processes and returns your picture.