chore: add --version flag

go.mod

@@ -8,6 +8,7 @@ require (
 	buf.build/gen/go/bufbuild/protovalidate/protocolbuffers/go v1.35.2-20241127180247-a33202765966.1
 	buf.build/gen/go/connectrpc/eliza/connectrpc/go v1.17.0-20230913231627-233fca715f49.1
 	buf.build/gen/go/connectrpc/eliza/protocolbuffers/go v1.34.2-20230913231627-233fca715f49.2
+	github.com/alecthomas/kong v1.6.1
 	github.com/bufbuild/protovalidate-go v0.7.3
 	github.com/golang/protobuf v1.5.4
 	github.com/google/gnostic v0.7.0

go.sum

@@ -610,6 +610,12 @@ github.com/ajstarks/deck v0.0.0-20200831202436-30c9fc6549a9/go.mod h1:JynElWSGnm
 github.com/ajstarks/deck/generate v0.0.0-20210309230005-c3f852c02e19/go.mod h1:T13YZdzov6OU0A1+RfKZiZN9ca6VeKdBdyDV+BY97Tk=
 github.com/ajstarks/svgo v0.0.0-20180226025133-644b8db467af/go.mod h1:K08gAheRH3/J6wwsYMMT4xOr94bZjxIelGM0+d/wbFw=
 github.com/ajstarks/svgo v0.0.0-20211024235047-1546f124cd8b/go.mod h1:1KcenG0jGWcpt8ov532z81sp/kMMUG485J2InIOyADM=
+github.com/alecthomas/assert/v2 v2.11.0 h1:2Q9r3ki8+JYXvGsDyBXwH3LcJ+WK5D0gc5E8vS6K3D0=
+github.com/alecthomas/assert/v2 v2.11.0/go.mod h1:Bze95FyfUr7x34QZrjL+XP+0qgp/zg8yS+TtBj1WA3k=
+github.com/alecthomas/kong v1.6.1 h1:/7bVimARU3uxPD0hbryPE8qWrS3Oz3kPQoxA/H2NKG8=
+github.com/alecthomas/kong v1.6.1/go.mod h1:p2vqieVMeTAnaC83txKtXe8FLke2X07aruPWXyMPQrU=
+github.com/alecthomas/repr v0.4.0 h1:GhI2A8MACjfegCPVq9f1FLvIBS+DrQ2KQBFZP1iFzXc=
+github.com/alecthomas/repr v0.4.0/go.mod h1:Fr0507jx4eOXV7AlPV6AVZLYrLIuIeSOWtW57eE/O/4=
 github.com/andybalholm/brotli v1.0.4/go.mod h1:fO7iG3H7G2nSZ7m0zPUDn85XEX2GTukHGRSepvi9Eig=
 github.com/antihax/optional v1.0.0/go.mod h1:uupD/76wgC+ih3iEmQUL+0Ugr19nfwCT1kdvxnR2qWY=
 github.com/apache/arrow/go/v10 v10.0.1/go.mod h1:YvhnlEePVnBS4+0z3fhPfUy7W1Ikj0Ih0vcRo/gZ1M0=
@@ -798,6 +804,8 @@ github.com/grpc-ecosystem/grpc-gateway/v2 v2.7.0/go.mod h1:hgWBS7lorOAVIJEQMi4Zs
 github.com/grpc-ecosystem/grpc-gateway/v2 v2.11.3/go.mod h1:o//XUCC/F+yRGJoPO/VU0GSB0f8Nhgmxx0VIRUvaC0w=
 github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
 github.com/hashicorp/golang-lru v0.5.1/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
+github.com/hexops/gotextdiff v1.0.3 h1:gitA9+qJrrTCsiCl7+kh75nPqQt1cx4ZkudSTLoUqJM=
+github.com/hexops/gotextdiff v1.0.3/go.mod h1:pSWU5MAI3yDq+fZBTazCSJysOMbxWL1BSow5/V2vxeg=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
 github.com/iancoleman/strcase v0.2.0/go.mod h1:iwCmte+B7n89clKwxIoIXy/HfoL7AsD47ZCWhYzw7ho=
 github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=

main.go

@@ -4,15 +4,48 @@ import (
 	"fmt"
 	"log/slog"
 	"os"
+	"runtime"
 
 	"google.golang.org/protobuf/proto"
 	pluginpb "google.golang.org/protobuf/types/pluginpb"
 
+	"github.com/alecthomas/kong"
 	"github.com/lmittmann/tint"
 	"github.com/sudorandom/protoc-gen-connect-openapi/internal/converter"
 )
 
+var (
+	version = "dev"
+	commit  = "none"
+	date    = "unknown"
+)
+
+type VersionFlag string
+
+func (v VersionFlag) Decode(ctx *kong.DecodeContext) error { return nil }
+func (v VersionFlag) IsBool() bool                         { return true }
+func (v VersionFlag) BeforeApply(app *kong.Kong, vars kong.Vars) error {
+	fmt.Println(vars["version"])
+	app.Exit(0)
+	return nil
+}
+
+type CLI struct {
+	Version VersionFlag `name:"version" help:"Print version information and quit"`
+}
+
 func main() {
+	version := fullVersion()
+	cli := CLI{
+		Version: VersionFlag(version),
+	}
+	_ = kong.Parse(&cli,
+		kong.Name("protoc-gen-connect-openapi"),
+		kong.Description("Plugin for generating OpenAPIv3 from protobufs matching the Connect RPC interface."),
+		kong.UsageOnError(),
+		kong.ConfigureHelp(kong.HelpOptions{Compact: true}),
+		kong.Vars{"version": version})
+
 	resp, err := converter.ConvertFrom(os.Stdin)
 	if err != nil {
 		message := fmt.Sprintf("Failed to read input: %v", err)
@@ -45,3 +78,6 @@ func renderResponse(resp *pluginpb.CodeGeneratorResponse) {
 		return
 	}
 }
+func fullVersion() string {
+	return fmt.Sprintf("%s (%s) @ %s; %s", version, commit, date, runtime.Version())
+}