add custom user for bin mode

_docs/unit.md

@@ -6,6 +6,7 @@
 Schema:
 
 * `command` (required, string) -  command to execute (will be executed in a shell)
+* `user` (optional, string) - custom user as process owner (only `bin` mode and only for linux), usually requires root privileges
 * `interval` (optional, interval) - interval between attempts
 * `timeout` (optional, interval) - maximum execution timeout (enabled only for bin mode and only if positive)
 * `graceful_timeout` (optional, interval) - maximum execution timeout after which SIGINT will be sent (enabled only for bin mode and only if positive).

server/mode_bin.go

@@ -34,6 +34,7 @@ func (m *markerResponse) WriteHeader(statusCode int) {
 }
 
 type binHandler struct {
+	user            string
 	command         string
 	workDir         string
 	shell           string
@@ -70,8 +71,13 @@ func (bh *binHandler) ServeHTTP(writer http.ResponseWriter, request *http.Reques
 	cmd.Stdout = marker
 	cmd.Env = env
 	internal.SetBinFlags(cmd)
-
-	err := bh.run(ctx, cmd)
+	err := setUser(cmd, bh.user)
+	if err != nil {
+		writer.Header().Set("X-Return-Code", strconv.Itoa(cmd.ProcessState.ExitCode()))
+		writer.WriteHeader(http.StatusInternalServerError)
+		return
+	}
+	err = bh.run(ctx, cmd)
 
 	if codeReset, ok := writer.(interface{ Status(status int) }); ok && err != nil {
 		codeReset.Status(http.StatusBadGateway)

server/mode_bin_default.go

@@ -0,0 +1,9 @@
+//+build !linux
+
+package server
+
+import "os/exec"
+
+func setUser(cmd *exec.Cmd, user string) error {
+	return nil
+}

server/mode_bin_linux.go

@@ -0,0 +1,35 @@
+package server
+
+import (
+	"os/exec"
+	"os/user"
+	"strconv"
+	"syscall"
+)
+
+func setUser(cmd *exec.Cmd, userName string) error {
+	if userName == "" {
+		return nil
+	}
+	info, err := user.Lookup(userName)
+	if err != nil {
+		return err
+	}
+	uid, err := strconv.Atoi(info.Uid)
+	if err != nil {
+		return err
+	}
+	gid, err := strconv.Atoi(info.Gid)
+	if err != nil {
+		return err
+	}
+
+	if cmd.SysProcAttr == nil {
+		cmd.SysProcAttr = &syscall.SysProcAttr{}
+	}
+	cmd.SysProcAttr.Credential = &syscall.Credential{
+		Uid: uint32(uid),
+		Gid: uint32(gid),
+	}
+	return nil
+}

server/unit.go

@@ -34,6 +34,7 @@ type Unit struct {
 	Mode            string            `yaml:"mode,omitempty"`             // execution mode: bin, cgi or proxy
 	WorkDir         string            `yaml:"workdir,omitempty"`          // working directory for the worker. if empty - temporary one will generated automatically
 	Command         string            `yaml:"command"`                    // command in a shell to execute
+	User            string            `yaml:"user,omitempty"`             // user name as process owner (only for bin mode)
 	Timeout         time.Duration     `yaml:"timeout,omitempty"`          // maximum execution timeout (enabled only for bin mode and only if positive)
 	GracefulTimeout time.Duration     `yaml:"graceful_timeout,omitempty"` // maximum execution timeout after which SIGINT will be sent (enabled only for bin mode and only if positive)
 	Shell           string            `yaml:"shell,omitempty"`            // shell to execute command in bin mode (default - /bin/sh)
@@ -258,6 +259,7 @@ func (cfg Unit) createRunner() (http.Handler, error) {
 	switch cfg.Mode {
 	case "bin":
 		return &binHandler{
+			user:            cfg.User,
 			command:         cfg.Command,
 			workDir:         cfg.WorkDir,
 			shell:           cfg.Shell,