How to add images into specific folder in Go? Getting error like: `%!(EXTRA *fs.PathError=open /photos: read-only file system)`

I am trying to put images into a specific folder in Golang. Here is the code below.
This is the function where I create a folder called photos in the root directory.

func createPhotoFolder(folderName string) {
	err := os.Mkdir(folderName, 777)
	if err != nil {
		fmt.Println("Error creating folder: ", err)
		return
	}
	fmt.Println(folderName, " created successfully in the root directory")
}

This is the function where I make get request to fetch image and try to put them into a photos folder I created earlier.

func downloadImages(urls []string) {
	for i, url := range urls {
		resp, err := http.Get(url)
		fmt.Printf("%d inside for loop\n", i)
		if err != nil {
			log.Fatal("error fetching image: ", err)
		}
		defer resp.Body.Close()
		out, err := os.Create("photos")
		if err != nil {
			log.Printf("Can't put image into folder: ", err)
		}
		defer out.Close()
	}
}

This is the error I get when I run the program.

1- If the folder name is written in this way os.Create("photos") without forwardslash I get the error message as below.

Can't put image into folder: %!(EXTRA *fs.PathError=open photos: is a directory)

2- If I write it like os.Create("/photos"). I get the error as below.

Can't put image into folder: %!(EXTRA *fs.PathError=open /photos: read-only file system)

I gave all the permission while creating the photos folder in the way of chmod.
I did try using io.Copy() but it requires a file parameter which I don't get while creating one using os.Create()

How should I create the folder and put the images inside it properly?

Here, in your code, in os.Create, it should have the complete address of the file to be created along with the name of the file to be created. Like:

gopath := "C:/Users/<username>/go/src/photos/" //where photos is the folder you created 
filename := "photo1.jpg"

out, err := os.Create(gopath + filename)

Also, as @steven-penny gave in his answer, create a filename from the image name directly from the url. So that you don't have to give the filename for each image you download.

out, err := os.create(gopath + filepath.Base(link))

And save the image to your system with,

out.Readfrom(resp.Body)

Here is a small program that does what I think you are trying to do:

package main

import (
   "net/http"
   "os"
   "path/filepath"
)

func downloadImages(links []string) error {
   tmp := os.TempDir()
   for _, link := range links {
      println(link)
      res, err := http.Get(link)
      if err != nil { return err }
      defer res.Body.Close()
      file, err := os.Create(filepath.Join(tmp, filepath.Base(link)))
      if err != nil { return err }
      defer file.Close()
      file.ReadFrom(res.Body)
   }
   return nil
}

func main() {
   links := []string{
      "http://cdn.sstatic.net/Sites/stackoverflow/Img/apple-touch-icon.png",
      "http://cdn.sstatic.net/Sites/stackoverflow/Img/favicon.ico",
   }
   err := downloadImages(links)
   if err != nil {
      panic(err)
   }
}

You'll want to modify it, as you were using a different directory, but it should get you started.

https://golang.org/pkg/os#File.ReadFrom