Add an "--output" flag to "pinniped get kubeconfig".

Signed-off-by: Matt Moyer <moyerm@vmware.com>

cmd/pinniped/cmd/kubeconfig.go

@@ -91,6 +91,7 @@ type getKubeconfigConciergeParams struct {
 type getKubeconfigParams struct {
 	kubeconfigPath            string
 	kubeconfigContextOverride string
+	outputPath                string
 	staticToken               string
 	staticTokenEnvName        string
 	oidc                      getKubeconfigOIDCParams
@@ -135,13 +136,24 @@ func kubeconfigCommand(deps kubeconfigDeps) *cobra.Command {
 	f.StringVar(&flags.oidc.requestAudience, "oidc-request-audience", "", "Request a token with an alternate audience using RFC8693 token exchange")
 	f.StringVar(&flags.kubeconfigPath, "kubeconfig", os.Getenv("KUBECONFIG"), "Path to kubeconfig file")
 	f.StringVar(&flags.kubeconfigContextOverride, "kubeconfig-context", "", "Kubeconfig context name (default: current active context)")
+	f.StringVarP(&flags.outputPath, "output", "o", "", "Output file path (default: stdout)")
 
 	mustMarkHidden(cmd, "oidc-debug-session-cache")
 
 	mustMarkDeprecated(cmd, "concierge-namespace", "not needed anymore")
 	mustMarkHidden(cmd, "concierge-namespace")
 
-	cmd.RunE = func(cmd *cobra.Command, args []string) error { return runGetKubeconfig(cmd.OutOrStdout(), deps, flags) }
+	cmd.RunE = func(cmd *cobra.Command, args []string) error {
+		if flags.outputPath != "" {
+			out, err := os.Create(flags.outputPath)
+			if err != nil {
+				return fmt.Errorf("could not open output file: %w", err)
+			}
+			defer func() { _ = out.Close() }()
+			cmd.SetOut(out)
+		}
+		return runGetKubeconfig(cmd.OutOrStdout(), deps, flags)
+	}
 	return cmd
 }
 

cmd/pinniped/cmd/kubeconfig_test.go

@@ -83,6 +83,7 @@ func TestGetKubeconfig(t *testing.T) {
 				      --oidc-scopes strings                   OpenID Connect scopes to request during login (default [offline_access,openid,pinniped:request-audience])
 				      --oidc-session-cache string             Path to OpenID Connect session cache file
 				      --oidc-skip-browser                     During OpenID Connect login, skip opening the browser (just print the URL)
+				  -o, --output string                         Output file path (default: stdout)
 				      --static-token string                   Instead of doing an OIDC-based login, specify a static token
 				      --static-token-env string               Instead of doing an OIDC-based login, read a static token from the environment
 			`),