Add flag --fail-on-error to zypp-plugin-mode

Currently container-suseconnect will fail with exit code 1 if it is not able to
obtain the SLE credentials. This is however causing UX issues in the SLE BCI
containers, which are perfectly fine without a SLE subscription.

Thus a new flag is introduced just for the mode when running as the zypper
plugin: `--fail-on-error`. When this flag is set or if the environment variable
`CONTAINER_SUSECONNECT_FAIL_ON_ERR` is set, then `container-suseconnect` will
fail as it did so far, but the default is now that errors will be silently
swallowed so that users of SLE BCI don't get confused by this error message.

Author: dcermak

cmd/container-suseconnect/main.go

@@ -57,6 +57,14 @@ func main() {
 	case "container-suseconnect-zypp":
 		app.Action = runZypperPlugin
 		defaultUsageAdditionZypp = " (default)"
+		app.Flags = []cli.Flag{
+			&cli.BoolFlag{
+				Name:    "fail-on-error",
+				Usage:   "Fail when an error occurs",
+				EnvVars: []string{"CONTAINER_SUSECONNECT_FAIL_ON_ERR"},
+			},
+		}
+
 	case "susecloud":
 		app.Action = runZypperURLResolver
 		defaultUsageAdditionZypp = " (default)"
@@ -165,11 +173,11 @@ func runZypperURLResolver(_ *cli.Context) error {
 // all available repositories for the installed product. Additional modules
 // can be specified via the `ADDITIONAL_MODULES` environment variable, which
 // reflect the module `identifier`.
-func runZypperPlugin(_ *cli.Context) error {
+func runZypperPlugin(ctx *cli.Context) error {
 	log.SetOutput(cs.GetLoggerFile())
 
 	products, err := requestProducts()
-	if err != nil {
+	if ctx.Bool("fail-on-error") && err != nil {
 		return err
 	}