feat: implement CLI command for policies

cmd/headscale/cli/policy.go

@@ -0,0 +1,91 @@
+package cli
+
+import (
+	"io"
+	"os"
+
+	"github.com/rs/zerolog/log"
+	"github.com/spf13/cobra"
+
+	v1 "github.com/juanfont/headscale/gen/go/headscale/v1"
+)
+
+func init() {
+	rootCmd.AddCommand(policyCmd)
+	policyCmd.AddCommand(getPolicy)
+
+	setPolicy.Flags().StringP("file", "f", "", "Path to a policy file in HuJSON format")
+	if err := setPolicy.MarkFlagRequired("file"); err != nil {
+		log.Fatal().Err(err).Msg("")
+	}
+	policyCmd.AddCommand(setPolicy)
+}
+
+var policyCmd = &cobra.Command{
+	Use:   "policy",
+	Short: "Manage the Headscale ACL Policy",
+}
+
+var getPolicy = &cobra.Command{
+	Use:     "get",
+	Short:   "Print the current ACL Policy",
+	Aliases: []string{"show", "view", "fetch"},
+	Run: func(cmd *cobra.Command, args []string) {
+		ctx, client, conn, cancel := getHeadscaleCLIClient()
+		defer cancel()
+		defer conn.Close()
+
+		request := &v1.GetPolicyRequest{}
+
+		response, err := client.GetPolicy(ctx, request)
+		if err != nil {
+			log.Fatal().Err(err).Msg("Failed to get the policy")
+
+			return
+		}
+
+		// TODO(pallabpain): Maybe print this better?
+		SuccessOutput("", response.GetPolicy(), "hujson")
+	},
+}
+
+var setPolicy = &cobra.Command{
+	Use:   "set",
+	Short: "Updates the ACL Policy",
+	Long: `
+	Updates the existing ACL Policy with the provided policy. The policy must be a valid HuJSON object.
+	This command only works when the acl.policy_mode is set to "db", and the policy will be stored in the database.`,
+	Aliases: []string{"put", "update"},
+	Run: func(cmd *cobra.Command, args []string) {
+		policyPath, _ := cmd.Flags().GetString("file")
+
+		f, err := os.Open(policyPath)
+		if err != nil {
+			log.Fatal().Err(err).Msg("Error opening the policy file")
+
+			return
+		}
+		defer f.Close()
+
+		policyBytes, err := io.ReadAll(f)
+		if err != nil {
+			log.Fatal().Err(err).Msg("Error reading the policy file")
+
+			return
+		}
+
+		request := &v1.SetPolicyRequest{Policy: string(policyBytes)}
+
+		ctx, client, conn, cancel := getHeadscaleCLIClient()
+		defer cancel()
+		defer conn.Close()
+
+		if _, err := client.SetPolicy(ctx, request); err != nil {
+			log.Fatal().Err(err).Msg("Failed to set ACL Policy")
+
+			return
+		}
+
+		SuccessOutput(nil, "Policy updated.", "")
+	},
+}