add graceful shutdown for bin mode

_docs/modes.md

@@ -0,0 +1,18 @@
+## BIN
+
+Binary modes just executes any script in shell (`/bin/sh` by default). You can override shell per-unit
+by `shell: /path/to/shell` configuration param.
+
+To handle a graceful timeout, child should be able to forward signal: basically, use `exec` before last command.
+
+Danger (but will work), signals may not be handled by foo
+
+```yaml
+command: "V=1 RAIL=2 foo bar -c -y -z"
+```
+
+Good
+
+```yaml
+command: "V=1 RAIL=2 exec foo bar -c -y -z"
+```

server/mode_bin.go

@@ -3,6 +3,7 @@ package server
 import (
 	"context"
 	"io/ioutil"
+	"log"
 	"net/http"
 	"os"
 	"os/exec"
@@ -38,6 +39,7 @@ type binHandler struct {
 	shell           string
 	environment     []string
 	timeout         time.Duration
+	gracefulTimeout time.Duration
 }
 
 func (bh *binHandler) ServeHTTP(writer http.ResponseWriter, request *http.Request) {
@@ -75,7 +77,29 @@ func (bh *binHandler) ServeHTTP(writer http.ResponseWriter, request *http.Reques
 	cmd.Stdout = marker
 	cmd.Env = env
 	api.SetBinFlags(cmd)
+
+	var done bool
+
+	if bh.gracefulTimeout > 0 {
+		graceCtx, graceCancel := context.WithTimeout(ctx, bh.gracefulTimeout)
+		defer graceCancel()
+		go func() {
+			<-graceCtx.Done()
+			proc := cmd.Process
+			if proc == nil || done {
+				return
+			}
+			err := proc.Signal(os.Interrupt)
+			if err != nil {
+				log.Println("failed send signal to process:", err)
+			} else {
+				log.Println("sent graceful shutdown to proces")
+			}
+		}()
+	}
+
 	err := cmd.Run()
+	done = true
 
 	if codeReset, ok := writer.(interface{ Status(status int) }); ok && err != nil {
 		codeReset.Status(http.StatusBadGateway)

server/unit.go

@@ -33,6 +33,7 @@ type Unit struct {
 	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
 	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)
 	Environment     map[string]string `yaml:"environment,omitempty"`      // custom environment for executable (in addition to system)
 	MaxRequest      int64             `yaml:"max_request,omitempty"`      // optional maximum HTTP body size (enabled if positive)
@@ -246,6 +247,7 @@ func (cfg Unit) createRunner() (http.Handler, error) {
 			workDir:         cfg.WorkDir,
 			shell:           cfg.Shell,
 			timeout:         cfg.Timeout,
+			gracefulTimeout: cfg.GracefulTimeout,
 			environment:     append(os.Environ(), makeEnvList(cfg.Environment)...),
 		}, nil
 	case "cgi":

templates/unit-info.html

@@ -50,7 +50,8 @@
                             <dd class="col-sm-9">{{.Unit.Attempts}}</dd>
                             <dt class="col-sm-3">Interval</dt>
                             <dd class="col-sm-9">{{.Unit.Interval}}</dd>
-                            <dt class="col-sm-3">Timeout</dt>
+                            {{if eq .Unit.Mode "bin"}}
+                                <dt class="col-sm-3" title="Timeout after which process will be sent">Timeout</dt>
                                 <dd class="col-sm-9">
                                     {{with .Unit.Timeout}}
                                         {{.}}
@@ -58,6 +59,16 @@
                                         ∞
                                     {{end}}
                                 </dd>
+                                <dt class="col-sm-3" title="Timeout after which SIGINT will be sent">Graceful timeout
+                                </dt>
+                                <dd class="col-sm-9">
+                                    {{with .Unit.GracefulTimeout}}
+                                        {{.}}
+                                    {{else}}
+                                        ∞
+                                    {{end}}
+                                </dd>
+                            {{end}}
                             <dt class="col-sm-3">Max request size</dt>
                             <dd class="col-sm-9">
                                 {{with .Unit.MaxRequest}}