Minor fixes in the connector publishing automation (#359)

1. Checks the HTTP response status to be 200 OK after downloading the
tar ball.
2. While extracting the tgz file, output the stdout and the stderr in
case of error.

registry-automation/cmd/utils.go

@@ -1,13 +1,15 @@
 package cmd
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
-	"gopkg.in/yaml.v2"
 	"io"
 	"net/http"
 	"os"
 	"os/exec"
+
+	"gopkg.in/yaml.v2"
 )
 
 func generateGCPObjectName(namespace, connectorName, version string) string {
@@ -16,7 +18,15 @@ func generateGCPObjectName(namespace, connectorName, version string) string {
 
 func downloadFile(sourceURL, destination string, headers map[string]string) error {
 	// Create a new HTTP client
-	client := &http.Client{}
+	client := &http.Client{
+		CheckRedirect: func(req *http.Request, via []*http.Request) error {
+			// Copy headers to redirected request
+			for key, values := range headers {
+				req.Header.Set(key, values)
+			}
+			return nil
+		},
+	}
 
 	// Create a new GET request
 	req, err := http.NewRequest("GET", sourceURL, nil)
@@ -36,6 +46,11 @@ func downloadFile(sourceURL, destination string, headers map[string]string) erro
 	}
 	defer resp.Body.Close()
 
+	// check the response status
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("Error downloading file: %s. HINT: Make sure that the tarball can be downloaded without any authentication", resp.Status)
+	}
+
 	// Create the destination file
 	outFile, err := os.Create(destination)
 	if err != nil {
@@ -111,12 +126,16 @@ func extractTarGz(src, dest string) (string, error) {
 	if err := os.MkdirAll(filepath, 0755); err != nil {
 		return "", fmt.Errorf("error creating destination directory: %v", err)
 	}
+	var stdout, stderr bytes.Buffer
 	// Run the tar command with the -xvzf options
 	cmd := exec.Command("tar", "-xvzf", src, "-C", dest)
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
 
 	// Execute the command
 	if err := cmd.Run(); err != nil {
-		return "", fmt.Errorf("error extracting tar.gz file: %v", err)
+		return "", fmt.Errorf("error extracting file:\nerror: %v\nstdout: %s\nstderr: %s",
+			err, stdout.String(), stderr.String())
 	}
 
 	return fmt.Sprintf("%s/.hasura-connector/connector-metadata.yaml", filepath), nil