Error: Connection refused when using Gmail API Go quickstart

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1

I’m trying to set up the Gmail API with Go using the quickstart guide, but I’m running into an issue when fetching the token via the web. When using the getTokenFromWeb function and pasting either the long URL or simply http://localhost:8000, I’m met with an error message stating that ‘localhost refused to connect’ along with ERR_CONNECTION_REFUSED.

Here’s a new code snippet that outlines what I’m attempting:

func fetchTokenFromWeb(config *oauth2.Config) *oauth2.Token {
    authURL := config.AuthCodeURL("state-token", oauth2.AccessTypeOffline)
    fmt.Printf("Visit this URL: %v\n", authURL)

    var code string
    fmt.Print("Input the code: ")
    if _, err := fmt.Scan(&code); err != nil {
        log.Fatalf("Cannot read the code: %v", err)
    }

    token, err := config.Exchange(context.TODO(), code)
    if err != nil {
        log.Fatalf("Cannot retrieve token: %v", err)
    }
    return token
}

Interestingly, the Python version of the quickstart works without this problem. I even tried using a token acquired by Python in the Go setup, and it functioned correctly. This suggests the issue is isolated to the token retrieval process in Go. Does anyone have any insight on what might be causing this or suggestions for a fix?

2

I’ve dealt with this exact issue before, and it can be frustrating. One thing that worked for me was explicitly setting up a local redirect URI in the Google Cloud Console. Go to your project, find the OAuth 2.0 Client IDs section, and add http://localhost:8000 as an authorized redirect URI.

Also, make sure you’re using the latest version of the Google API client library for Go. Older versions sometimes had quirks with local auth flows.

If you’re still stuck, try running your Go app with elevated privileges (sudo on Linux/Mac, or as admin on Windows). Sometimes local port binding can be finicky without the right permissions.

Lastly, double-check that your client_secret.json file is up to date and in the correct directory. I once spent hours debugging only to realize I had an outdated secrets file!

3

hey ethan, sounds like a tricky one! have u checked if ur firewall is blocking localhost:8000? also, make sure ur not running anything else on that port. try changing the port in ur config and see if that helps. good luck!

4

I’ve encountered a similar issue when working with OAuth flows in Go. The problem likely stems from how the local server is set up to handle the callback. Ensure you have a local HTTP server listening on the specified port (8000 in this case) to catch the callback. You might need to implement a simple HTTP handler to receive the authorization code.

Here’s a potential modification to your code:

http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
    code := r.URL.Query().Get("code")
    if code != "" {
        fmt.Fprintf(w, "Authorization code: %s", code)
        // Use this code to exchange for the token
    }
})
go http.ListenAndServe(":8000", nil)

Then proceed with your existing code to exchange the code for a token. This should resolve the connection refused error by properly handling the OAuth callback.