cmd/resolver: implement sub command to update environment

The env command now accept sub command "update" with argument path to
the file or "-" for standard input.
The content of file is formatted using JSON, the same as output of "env"
command.
If the content of file is valid, server will be restarted immediately.

2 files changed, 81 insertions, 2 deletions

diff --git a/cmd/resolver/main.go b/cmd/resolver/main.go
index 90fcc68..f2d4baf 100644
--- a/cmd/resolver/main.go
+++ b/cmd/resolver/main.go
@@ -21,6 +21,7 @@ const (
 
 	subCmdSearch = "search"
 	subCmdRemove = "remove"
+	subCmdUpdate = "update"
 )
 
 func main() {
@@ -29,6 +30,7 @@ func main() {
 
 		subCmd  string
 		args    []string
+		err     error
 		optHelp bool
 	)
 
@@ -85,7 +87,29 @@ func main() {
 		}
 
 	case cmdEnv:
-		rsol.doCmdEnv()
+		args = args[1:]
+		if len(args) == 0 {
+			rsol.doCmdEnv()
+			return
+		}
+
+		subCmd = strings.ToLower(args[0])
+		switch subCmd {
+		case subCmdUpdate:
+			args = args[1:]
+			if len(args) == 0 {
+				log.Fatalf("resolver: %s %s: missing file argument", rsol.cmd, subCmd)
+			}
+
+			err = rsol.doCmdEnvUpdate(args[0])
+			if err != nil {
+				log.Fatalf("resolver: %s", err)
+			}
+
+		default:
+			log.Printf("resolver: %s: unknown sub command: %s", rsol.cmd, subCmd)
+			os.Exit(2)
+		}
 
 	case cmdQuery:
 		args = args[1:]
@@ -174,6 +198,12 @@ env
 	Fetch the current server environment and print it as JSON format to
 	stdout.
 
+env update <path-to-file / "-">
+
+	Update the server environment from JSON formatted file.
+	If the argument is "-", the new environment is read from stdin.
+	If the environment is valid, the server will be restarted.
+
 
 ==  Examples
 
@@ -218,5 +248,13 @@ Remove all caches in the server,
 
 Fetch and print current server environment,
 
-	$ resolver env`)
+	$ resolver env
+
+Update the server environment from JSON file in /tmp/env.json,
+
+	$ resolver env update /tmp/env.json
+
+Update the server environment by reading JSON from standard input,
+
+	$ cat /tmp/env.json | resolver env update -`)
 }
diff --git a/cmd/resolver/resolver.go b/cmd/resolver/resolver.go
index b7129cc..697953d 100644
--- a/cmd/resolver/resolver.go
+++ b/cmd/resolver/resolver.go
@@ -6,8 +6,10 @@ package main
 import (
 	"encoding/json"
 	"fmt"
+	"io"
 	"log"
 	"math/rand"
+	"os"
 	"strings"
 	"time"
 
@@ -128,6 +130,45 @@ func (rsol *resolver) doCmdEnv() {
 	fmt.Printf("%s\n", envJson)
 }
 
+// doCmdEnvUpdate update the server environment by reading the JSON formatted
+// environment from file or from stdin.
+func (rsol *resolver) doCmdEnvUpdate(fileOrStdin string) (err error) {
+	var (
+		resc = rsol.newRescachedClient()
+
+		env     *rescached.Environment
+		envJson []byte
+	)
+
+	if fileOrStdin == "-" {
+		envJson, err = io.ReadAll(os.Stdin)
+	} else {
+		envJson, err = os.ReadFile(fileOrStdin)
+	}
+	if err != nil {
+		return fmt.Errorf("%s %s: %w", cmdEnv, subCmdUpdate, err)
+	}
+
+	err = json.Unmarshal(envJson, &env)
+	if err != nil {
+		return fmt.Errorf("%s %s: %w", cmdEnv, subCmdUpdate, err)
+	}
+
+	env, err = resc.EnvUpdate(env)
+	if err != nil {
+		return fmt.Errorf("%s %s: %w", cmdEnv, subCmdUpdate, err)
+	}
+
+	envJson, err = json.MarshalIndent(env, "", "  ")
+	if err != nil {
+		return fmt.Errorf("%s %s: %w", cmdEnv, subCmdUpdate, err)
+	}
+
+	fmt.Printf("%s\n", envJson)
+
+	return nil
+}
+
 func (rsol *resolver) doCmdQuery(args []string) {
 	var (
 		maxAttempts = defAttempts