From 78d1e44add2e0ea5e73dd97921551199943916fc Mon Sep 17 00:00:00 2001
From: Ondrej Belusky <zlymeda@gmail.com>
Date: Sat, 21 Feb 2026 12:56:58 +0100
Subject: [PATCH] added nats-exec

---
 .gitignore                         |   2 +
 README.md                          |  27 ++++++
 action.yml                         |   2 +-
 cmd/nats-exec/main.go              | 146 +++++++++++++++++++++++++++++
 main.go => cmd/nats-upload/main.go |   0
 5 files changed, 176 insertions(+), 1 deletion(-)
 create mode 100644 cmd/nats-exec/main.go
 rename main.go => cmd/nats-upload/main.go (100%)

diff --git a/.gitignore b/.gitignore
index 5b90e79..4d47125 100644
--- a/.gitignore
+++ b/.gitignore
@@ -25,3 +25,5 @@ go.work.sum
 # env file
 .env
 
+./bin
+bin
diff --git a/README.md b/README.md
index 64d81b4..635817d 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,29 @@
 # nats-upload
 
+Tooling for uploading and executing binaries via NATS Object Store.
+
+## nats-upload
+
+A GitHub Action to upload binaries to a NATS Object Store for self-update.
+
+## nats-exec
+
+A tool to download and execute the latest version of a binary from NATS Object Store.
+
+### Usage
+
+```bash
+nats-exec <binary-name> [args...]
+```
+
+Example:
+```bash
+nats-exec mybinary version
+```
+
+### Environment Variables
+
+- `NATS_URL`: NATS server URL (default: `nats://localhost:4222`)
+- `NATS_BUCKET`: Object store bucket name (default: `binaries`)
+- `NATS_CACHE_DIR`: Local cache directory (default: `/tmp/nats-exec-cache`)
+
diff --git a/action.yml b/action.yml
index c575a40..a9b13bf 100644
--- a/action.yml
+++ b/action.yml
@@ -39,4 +39,4 @@ inputs:
     default: 'false'
 runs:
   using: 'go'
-  main: 'main.go'
+  main: 'cmd/nats-upload/main.go'
diff --git a/cmd/nats-exec/main.go b/cmd/nats-exec/main.go
new file mode 100644
index 0000000..0eca092
--- /dev/null
+++ b/cmd/nats-exec/main.go
@@ -0,0 +1,146 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"syscall"
+
+	"github.com/nats-io/nats.go"
+	"github.com/nats-io/nats.go/jetstream"
+	"golang.org/x/mod/semver"
+)
+
+func main() {
+	if len(os.Args) < 2 {
+		_, _ = fmt.Fprintf(os.Stderr, "Usage: %s <binary-name> [args...]\n", os.Args[0])
+		os.Exit(1)
+	}
+
+	binaryName := os.Args[1]
+	remainingArgs := os.Args[2:]
+
+	natsURL := getEnv("NATS_URL", "nats://localhost:4222")
+	bucketName := getEnv("NATS_BUCKET", "binaries")
+	cacheDir := getEnv("NATS_CACHE_DIR", filepath.Join(os.TempDir(), "nats-exec-cache"))
+
+	ctx := context.Background()
+
+	nc, err := nats.Connect(natsURL)
+	if err != nil {
+		log.Fatalf("Failed to connect to NATS: %v", err)
+	}
+	defer nc.Close()
+
+	js, err := jetstream.New(nc)
+	if err != nil {
+		log.Fatalf("Failed to create JetStream context: %v", err)
+	}
+
+	store, err := js.ObjectStore(ctx, bucketName)
+	if err != nil {
+		log.Fatalf("Failed to get object store %s: %v", bucketName, err)
+	}
+
+	// Format: binary/arch/version
+	arch := runtime.GOARCH
+
+	objects, err := store.List(ctx)
+	if err != nil {
+		log.Fatalf("Failed to list objects: %v", err)
+	}
+
+	var latestVersion string
+	var latestKey string
+
+	for _, info := range objects {
+		// Key structure: <binaryName>/<arch>/<version>
+
+		parts := strings.Split(info.Name, "/")
+		if len(parts) != 3 {
+			continue
+		}
+		if parts[0] != binaryName {
+			continue
+		}
+		if parts[1] != arch {
+			continue
+		}
+
+		version := parts[2]
+		if !strings.HasPrefix(version, "v") {
+			version = "v" + version
+		}
+
+		if semver.IsValid(version) {
+			if latestVersion == "" || semver.Compare(version, latestVersion) > 0 {
+				latestVersion = version
+				latestKey = info.Name
+			}
+		}
+	}
+
+	if latestKey == "" {
+		log.Fatalf("No version of %s found for arch %s", binaryName, arch)
+	}
+
+	localPath := filepath.Join(cacheDir, latestKey)
+
+	if _, err := os.Stat(localPath); os.IsNotExist(err) {
+		log.Printf("Downloading %s version %s...", binaryName, latestVersion)
+		if err := downloadBinary(ctx, store, latestKey, localPath); err != nil {
+			log.Fatalf("Failed to download binary: %v", err)
+		}
+	} else {
+		log.Printf("Using cached %s version %s", binaryName, latestVersion)
+	}
+
+	if err := os.Chmod(localPath, 0755); err != nil {
+		log.Fatalf("Failed to make binary executable: %v", err)
+	}
+
+	fullPath, err := filepath.Abs(localPath)
+	if err != nil {
+		log.Fatalf("Failed to get absolute path: %v", err)
+	}
+
+	env := os.Environ()
+	args := append([]string{fullPath}, remainingArgs...)
+
+	err = syscall.Exec(fullPath, args, env)
+	if err != nil {
+		log.Fatalf("Failed to exec %s: %v", fullPath, err)
+	}
+}
+
+func downloadBinary(ctx context.Context, store jetstream.ObjectStore, key, localPath string) error {
+	if err := os.MkdirAll(filepath.Dir(localPath), 0755); err != nil {
+		return err
+	}
+
+	obj, err := store.Get(ctx, key)
+	if err != nil {
+		return err
+	}
+
+	f, err := os.OpenFile(localPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0755)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	_, err = io.Copy(f, obj)
+	return err
+}
+
+func getEnv(key, defaultValue string) string {
+	if value, ok := os.LookupEnv(key); ok {
+		return value
+	}
+	return defaultValue
+}
diff --git a/main.go b/cmd/nats-upload/main.go
similarity index 100%
rename from main.go
rename to cmd/nats-upload/main.go