dnfjson: append name and URL a repository to error message

If dnf-json returns an error that is related to a repository, it uses
the ID to identify the repository that caused the error.  Since IDs
can't easily be mapped back to a configuration, appending the URL and
name (if any) to the error message makes it easier to identify which
repository failed.
Keeping the ID in the message is also useful for finding the cache
directory of the repository if needed.

internal/dnfjson/dnfjson.go

@@ -21,6 +21,7 @@ import (
 	"os"
 	"os/exec"
 	"sort"
+	"strings"
 	"time"
 
 	"github.com/osbuild/osbuild-composer/internal/rhsm"
@@ -407,8 +408,10 @@ func (err Error) Error() string {
 	return fmt.Sprintf("DNF error occurred: %s: %s", err.Kind, err.Reason)
 }
 
-// parseError parses the response from dnf-json into the Error type.
-func parseError(data []byte) Error {
+// parseError parses the response from dnf-json into the Error type and appends
+// the name and URL of a repository to all detected repository IDs in the
+// message.
+func parseError(data []byte, repos []repoConfig) Error {
 	var e Error
 	if err := json.Unmarshal(data, &e); err != nil {
 		// dumping the error into the Reason can get noisy, but it's good for troubleshooting
@@ -417,6 +420,25 @@ func parseError(data []byte) Error {
 			Reason: fmt.Sprintf("Failed to unmarshal dnf-json error output %q: %s", string(data), err.Error()),
 		}
 	}
+
+	// append to any instance of a repository ID the URL (or metalink, mirrorlist, etc)
+	for _, repo := range repos {
+		idstr := fmt.Sprintf("'%s'", repo.ID)
+		var nameURL string
+		if len(repo.BaseURL) > 0 {
+			nameURL = repo.BaseURL
+		} else if len(repo.Metalink) > 0 {
+			nameURL = repo.Metalink
+		} else if len(repo.MirrorList) > 0 {
+			nameURL = repo.MirrorList
+		}
+
+		if len(repo.Name) > 0 {
+			nameURL = fmt.Sprintf("%s: %s", repo.Name, nameURL)
+		}
+		e.Reason = strings.Replace(e.Reason, idstr, fmt.Sprintf("%s [%s]", idstr, nameURL), -1)
+	}
+
 	return e
 }
 
@@ -453,7 +475,7 @@ func run(dnfJsonCmd []string, req *Request) ([]byte, error) {
 	err = cmd.Wait()
 	output := stdout.Bytes()
 	if runError, ok := err.(*exec.ExitError); ok && runError.ExitCode() != 0 {
-		return nil, parseError(output)
+		return nil, parseError(output, req.Arguments.Repos)
 	}
 
 	return output, nil