Add excludepkgs option to repo command

This features may help users guarantee correctness of bundles built by mixer in
lieu of some shortcomings with dnf where dnf produces an unexpected dependency
solution. This mainly happens when a user is intending to fully substitute
a package from upstream's repo with one from their own. If anything is wrong
with the substitution, a feature like this would expose the issue early on.

Signed-off-by: Tudor Marcu <tudor.marcu@intel.com>

builder/builder.go

@@ -1839,6 +1839,33 @@ func (b *Builder) SetURLRepo(name, url string) error {
 	return DNFConf.SaveTo(b.Config.Builder.DNFConf)
 }
 
+// SetExcludesRepo sets the ecludes for the repo <name> to [pkgs...]
+func (b *Builder) SetExcludesRepo(reponame, pkgs string) error {
+	if err := b.NewDNFConfIfNeeded(); err != nil {
+		return err
+	}
+
+	DNFConf, err := ini.Load(b.Config.Builder.DNFConf)
+	if err != nil {
+		return err
+	}
+
+	s, err := DNFConf.GetSection(reponame)
+	if err != nil {
+		return err
+	}
+
+	k, err := s.GetKey("excludepkgs")
+	if err != nil {
+		if k, err = DNFConf.Section(reponame).NewKey("excludepkgs", pkgs); err != nil {
+			return err
+		}
+	}
+
+	k.SetValue(pkgs)
+	return DNFConf.SaveTo(b.Config.Builder.DNFConf)
+}
+
 // RemoveRepo removes a configured repo <name> if it exists in the DNF configuration.
 // This will fail if a DNF conf has not yet been generated.
 func (b *Builder) RemoveRepo(name string) error {

mixer/cmd/repos.go

@@ -16,6 +16,7 @@ package cmd
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/clearlinux/mixer-tools/builder"
 
@@ -66,12 +67,21 @@ var setURLRepoCmd = &cobra.Command{
 	Run:   runSetURLRepo,
 }
 
+var setExcludesRepoCmd = &cobra.Command{
+	Use:   "exclude <repo> <pkg> [<pkg>...]",
+	Short: "Exclude packages from a specified repo",
+	Long:  `Exclude packages from a specified repo. These packages will be ignored during build bundles. Globbing is supported.`,
+	Args:  cobra.MinimumNArgs(2),
+	Run:   runExcludesRepo,
+}
+
 var repoCmds = []*cobra.Command{
 	addRepoCmd,
 	removeRepoCmd,
 	listReposCmd,
 	initRepoCmd,
 	setURLRepoCmd,
+	setExcludesRepoCmd,
 }
 
 func init() {
@@ -83,6 +93,19 @@ func init() {
 	RootCmd.AddCommand(repoCmd)
 }
 
+func runExcludesRepo(cmd *cobra.Command, args []string) {
+	b, err := builder.NewFromConfig(configFile)
+	if err != nil {
+		fail(err)
+	}
+
+	err = b.SetExcludesRepo(args[0], strings.Join(args[1:], " "))
+	if err != nil {
+		fail(err)
+	}
+	fmt.Printf("Excluded packages from repo %s:\n%s\n", args[0], strings.Join(args[1:], "\n"))
+}
+
 func runAddRepo(cmd *cobra.Command, args []string) {
 	b, err := builder.NewFromConfig(configFile)
 	if err != nil {