Emit version in JSON format for --json-version

config/flags.go

@@ -69,6 +69,7 @@ func deprecateFlags(fs *pflag.FlagSet) error {
 func addProcessFlags(fs *pflag.FlagSet) {
 	// If true, print the version and quit.
 	fs.Bool(VersionKey, false, "If true, print version and quit")
+	fs.Bool(VersionJSONKey, false, "If true, print version in JSON format and quit")
 }
 
 func addNodeFlags(fs *pflag.FlagSet) {

config/keys.go

@@ -13,6 +13,7 @@ const (
 	ConfigContentKey                 = "config-file-content"
 	ConfigContentTypeKey             = "config-file-content-type"
 	VersionKey                       = "version"
+	VersionJSONKey                   = "version-json"
 	GenesisFileKey                   = "genesis-file"
 	GenesisFileContentKey            = "genesis-file-content"
 	NetworkNameKey                   = "network-id"

main/main.go

@@ -4,6 +4,7 @@
 package main
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"os"
@@ -29,8 +30,24 @@ func main() {
 		os.Exit(1)
 	}
 
+	if v.GetBool(config.VersionJSONKey) && v.GetBool(config.VersionKey) {
+		fmt.Println("can't print both JSON and human readable versions")
+		os.Exit(1)
+	}
+
+	if v.GetBool(config.VersionJSONKey) {
+		versions := version.GetVersions()
+		jsonBytes, err := json.MarshalIndent(versions, "", "  ")
+		if err != nil {
+			fmt.Printf("couldn't marshal versions: %s\n", err)
+			os.Exit(1)
+		}
+		fmt.Println(string(jsonBytes))
+		os.Exit(0)
+	}
+
 	if v.GetBool(config.VersionKey) {
-		fmt.Print(version.String)
+		fmt.Println(version.GetVersions().String())
 		os.Exit(0)
 	}
 

version/string.go

@@ -9,32 +9,37 @@ import (
 	"strings"
 )
 
-var (
-	// String is displayed when CLI arg --version is used
-	String string
+// GitCommit is set in the build script at compile time
+var GitCommit string
 
-	// GitCommit is set in the build script at compile time
-	GitCommit string
-)
+// Versions contains the versions relevant to a build of avalanchego. In
+// addition to supporting construction of the string displayed by
+// --version, it is used to produce the output of --version-json and can
+// be used to unmarshal that output.
+type Versions struct {
+	Application string `json:"application"`
+	Database    string `json:"database"`
+	RPCChainVM  uint64 `json:"rpcchainvm"`
+	// Commit may be empty if GitCommit was not set at compile time
+	Commit string `json:"commit"`
+	Go     string `json:"go"`
+}
 
-func init() {
-	format := "%s [database=%s, rpcchainvm=%d"
-	args := []interface{}{
-		CurrentApp,
-		CurrentDatabase,
-		RPCChainVMProtocol,
-	}
-	if GitCommit != "" {
-		format += ", commit=%s"
-		args = append(args, GitCommit)
+func GetVersions() *Versions {
+	return &Versions{
+		Application: CurrentApp.String(),
+		Database:    CurrentDatabase.String(),
+		RPCChainVM:  uint64(RPCChainVMProtocol),
+		Commit:      GitCommit,
+		Go:          strings.TrimPrefix(runtime.Version(), "go"),
 	}
+}
 
-	// add golang version
-	goVersion := runtime.Version()
-	goVersionNumber := strings.TrimPrefix(goVersion, "go")
-	format += ", go=%s"
-	args = append(args, goVersionNumber)
-
-	format += "]\n"
-	String = fmt.Sprintf(format, args...)
+func (v *Versions) String() string {
+	// This format maintains consistency with previous --version output
+	versionString := fmt.Sprintf("%s [database=%s, rpcchainvm=%d, ", v.Application, v.Database, v.RPCChainVM)
+	if len(v.Commit) > 0 {
+		versionString += fmt.Sprintf("commit=%s, ", v.Commit)
+	}
+	return versionString + fmt.Sprintf("go=%s]", v.Go)
 }

version/string_test.go

@@ -0,0 +1,23 @@
+// Copyright (C) 2019-2024, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package version
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestVersionsGetString(t *testing.T) {
+	versions := Versions{
+		Application: "1",
+		Database:    "2",
+		RPCChainVM:  3,
+		Commit:      "4",
+		Go:          "5",
+	}
+	require.Equal(t, "1 [database=2, rpcchainvm=3, commit=4, go=5]", versions.String())
+	versions.Commit = ""
+	require.Equal(t, "1 [database=2, rpcchainvm=3, go=5]", versions.String())
+}