Merge "server: restart camlistored from the /status handler"

pkg/server/app/app.go

@@ -19,6 +19,7 @@ limitations under the License.
 package app
 
 import (
+	"errors"
 	"fmt"
 	"log"
 	"net"
@@ -29,6 +30,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"strings"
+	"time"
 
 	"camlistore.org/pkg/auth"
 	camhttputil "camlistore.org/pkg/httputil"
@@ -46,6 +48,8 @@ type Handler struct {
 
 	proxy      *httputil.ReverseProxy // For redirecting requests to the app.
 	backendURL string                 // URL that we proxy to (i.e. base URL of the app).
+
+	process *os.Process // The app's Pid. To send it signals on restart, etc.
 }
 
 func (a *Handler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
@@ -217,6 +221,7 @@ func (a *Handler) Start() error {
 	if err := cmd.Start(); err != nil {
 		return fmt.Errorf("could not start app %v: %v", name, err)
 	}
+	a.process = cmd.Process
 	return nil
 }
 
@@ -243,3 +248,27 @@ func (a *Handler) AppConfig() map[string]interface{} {
 func (a *Handler) BackendURL() string {
 	return a.backendURL
 }
+
+var errProcessTookTooLong = errors.New("proccess took too long to quit")
+
+// Quit sends the app's process a SIGINT, and waits up to 5 seconds for it
+// to exit, returning an error if it doesn't.
+func (a *Handler) Quit() error {
+	err := a.process.Signal(os.Interrupt)
+	if err != nil {
+		return err
+	}
+
+	c := make(chan error)
+	go func() {
+		_, err := a.process.Wait()
+		c <- err
+	}()
+	select {
+	case err = <-c:
+	case <-time.After(5 * time.Second):
+		// TODO Do we want to SIGKILL here or just leave the app alone?
+		err = errProcessTookTooLong
+	}
+	return err
+}

pkg/server/app/app_test.go

@@ -17,6 +17,11 @@ limitations under the License.
 package app
 
 import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
 	"regexp"
 	"testing"
 )
@@ -148,3 +153,68 @@ func TestRandPortBackendURL(t *testing.T) {
 		}
 	}
 }
+
+// We just want a helper command that ignores SIGINT.
+func ignoreInterrupt() (*os.Process, error) {
+	script := `trap "echo hello" SIGINT
+echo READY
+sleep 10000`
+	cmd := exec.Command("bash")
+
+	w, err := cmd.StdinPipe()
+	if err != nil {
+		return nil, fmt.Errorf("couldn't get pipe for helper shell")
+	}
+	go io.WriteString(w, script)
+
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		return nil, fmt.Errorf("couldn't get pipe for helper shell")
+	}
+
+	err = cmd.Start()
+	if err != nil {
+		return nil, fmt.Errorf("couldn't start helper shell")
+	}
+
+	r := bufio.NewReader(stdout)
+	l, err := r.ReadBytes('\n')
+	if err != nil {
+		return nil, fmt.Errorf("couldn't read from helper shell")
+	}
+	if string(l) != "READY\n" {
+		return nil, fmt.Errorf("unexpected output from helper shell script")
+	}
+	return cmd.Process, nil
+}
+
+func TestQuit(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping test in short mode")
+	}
+
+	cmd := exec.Command("sleep", "10000")
+	err := cmd.Start()
+	if err != nil {
+		t.Skip("couldn't run test helper command")
+	}
+	h := Handler{
+		process: cmd.Process,
+	}
+	err = h.Quit()
+	if err != nil {
+		t.Errorf("got %v, wanted %v", err, nil)
+	}
+
+	pid, err := ignoreInterrupt()
+	if err != nil {
+		t.Skip("couldn't run test helper command: %v", err)
+	}
+	h = Handler{
+		process: pid,
+	}
+	err = h.Quit()
+	if err != errProcessTookTooLong {
+		t.Errorf("got %v, wanted %v", err, errProcessTookTooLong)
+	}
+}

pkg/server/status.go

@@ -33,7 +33,9 @@ import (
 	"camlistore.org/pkg/httputil"
 	"camlistore.org/pkg/index"
 	"camlistore.org/pkg/jsonconfig"
+	"camlistore.org/pkg/osutil"
 	"camlistore.org/pkg/search"
+	"camlistore.org/pkg/server/app"
 	"camlistore.org/pkg/types/camtypes"
 )
 
@@ -86,6 +88,10 @@ func (sh *StatusHandler) InitHandler(hl blobserver.FindHandlerByTyper) error {
 
 func (sh *StatusHandler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 	suffix := httputil.PathSuffix(req)
+	if suffix == "restart" {
+		sh.serveRestart(rw, req)
+		return
+	}
 	if !httputil.IsGet(req) {
 		http.Error(rw, "Illegal status method.", http.StatusMethodNotAllowed)
 		return
@@ -208,6 +214,7 @@ func (sh *StatusHandler) serveStatusHTML(rw http.ResponseWriter, req *http.Reque
 	}
 	f("<html><head><title>Status</title></head>")
 	f("<body><h2>Status</h2>")
+	f("<form method='post' action='restart' onsubmit='return confirm(\"Really restart now?\")'><button>restart server</button></form>")
 	f("<p>As JSON: <a href='status.json'>status.json</a>; and the <a href='%s?camli.mode=config'>discovery JSON</a>.</p>", st.rootPrefix)
 	f("<p>Not yet pretty HTML UI:</p>")
 	js, err := json.MarshalIndent(st, "", "  ")
@@ -224,3 +231,34 @@ func (sh *StatusHandler) serveStatusHTML(rw http.ResponseWriter, req *http.Reque
 	})
 	f("<pre>%s</pre>", jsh)
 }
+
+func (sh *StatusHandler) serveRestart(rw http.ResponseWriter, req *http.Request) {
+	if req.Method != "POST" {
+		http.Error(rw, "POST to restart", http.StatusMethodNotAllowed)
+		return
+	}
+
+	_, handlers := sh.handlerFinder.AllHandlers()
+	for _, h := range handlers {
+		ah, ok := h.(*app.Handler)
+		if !ok {
+			continue
+		}
+		log.Printf("Sending SIGINT to %s", ah.ProgramName())
+		err := ah.Quit()
+		if err != nil {
+			msg := fmt.Sprintf("Not restarting: couldn't interrupt app %s: %v", ah.ProgramName(), err)
+			log.Printf(msg)
+			http.Error(rw, msg, http.StatusInternalServerError)
+			return
+		}
+	}
+
+	log.Println("Restarting camlistored")
+	rw.Header().Set("Connection", "close")
+	http.Redirect(rw, req, sh.prefix, http.StatusFound)
+	if f, ok := rw.(http.Flusher); ok {
+		f.Flush()
+	}
+	osutil.RestartProcess()
+}