Merge pull request #38 from GCS-de/master

SIGUSR2 now triggers a graceful shutdown and reloads the crontab configuration

README.md

@@ -39,6 +39,7 @@ a container to behave:
 - `SIGTERM` triggers a graceful shutdown (and so does `SIGINT`, which you can
   deliver via CTRL+C when used interactively)
 - Job return codes and schedules are logged to `stdout` / `stderr`
+- `SIGUSR2` triggers a graceful shutdown and reloads the crontab configuration
 
 ## How does it work? ##
 
@@ -204,6 +205,18 @@ WARN[2017-07-11T12:24:32+02:00] job took too long to run: it should have started
 ```
 
 
+## Reload crontab
+
+Send `SIGUSR2` to Supercronic to reload the crontab:
+
+```bash
+# docker environment (Supercronic needs to be PID 1 in the container)
+docker kill --signal=USR2 <container id>
+
+# shell
+kill -USR2 <pid>
+```
+
 ## Testing your crontab
 
 Use the `-test` flag to prompt Supercronic to verify your crontab, but not

integration/reload.bats

@@ -0,0 +1,44 @@
+#!/usr/bin/env bats
+
+setup() {
+  CRONTAB_FILE="$(mktemp)"
+  TEST_FILE="$(mktemp)"
+
+  export TEST_FILE
+}
+
+teardown() {
+  rm "$TEST_FILE"
+}
+
+wait_for() {
+  for i in $(seq 0 5); do
+    if "$@" > /dev/null 2>&1; then
+      return 0
+    fi
+
+    sleep 1
+  done
+
+  return 1
+}
+
+grep_test_file() {
+  grep -- "$1" "$TEST_FILE"
+}
+
+@test "it reloads on SIGUSR2" {
+  echo '* * * * * * * echo a > "$TEST_FILE"' > "$CRONTAB_FILE"
+
+  "${BATS_TEST_DIRNAME}/../supercronic" "$CRONTAB_FILE" 3>&- &
+  PID="$!"
+
+  wait_for grep_test_file a
+
+  echo '* * * * * * * echo b > "$TEST_FILE"' > "$CRONTAB_FILE"
+  kill -s USR2 "$PID"
+  wait_for grep_test_file b
+
+  kill -s TERM "$PID"
+  wait
+}

integration/test.bats

@@ -1,3 +1,5 @@
+#!/usr/bin/env bats
+
 function run_supercronic() {
   local crontab="$1"
   local timeout="${2:-1s}"

main.go

@@ -65,20 +65,6 @@ func main() {
 	}
 
 	crontabFileName := flag.Args()[0]
-	logrus.Infof("read crontab: %s", crontabFileName)
-
-	tab, err := readCrontabAtPath(crontabFileName)
-
-	if err != nil {
-		logrus.Fatal(err)
-		return
-	}
-
-	if *test {
-		logrus.Info("crontab is valid")
-		os.Exit(0)
-		return
-	}
 
 	var sentryHook *logrus_sentry.SentryHook
 	if sentryDsn != "" {
@@ -100,31 +86,54 @@ func main() {
 		}
 	}
 
-	var wg sync.WaitGroup
-	exitCtx, notifyExit := context.WithCancel(context.Background())
+	for true {
+		logrus.Infof("read crontab: %s", crontabFileName)
+		tab, err := readCrontabAtPath(crontabFileName)
+
+		if err != nil {
+			logrus.Fatal(err)
+			break
+		}
+
+		if *test {
+			logrus.Info("crontab is valid")
+			os.Exit(0)
+			break
+		}
 
-	for _, job := range tab.Jobs {
-		cronLogger := logrus.WithFields(logrus.Fields{
-			"job.schedule": job.Schedule,
-			"job.command":  job.Command,
-			"job.position": job.Position,
-		})
+		var wg sync.WaitGroup
+		exitCtx, notifyExit := context.WithCancel(context.Background())
 
-		cron.StartJob(&wg, tab.Context, job, exitCtx, cronLogger)
-	}
+		for _, job := range tab.Jobs {
+			cronLogger := logrus.WithFields(logrus.Fields{
+				"job.schedule": job.Schedule,
+				"job.command":  job.Command,
+				"job.position": job.Position,
+			})
+
+			cron.StartJob(&wg, tab.Context, job, exitCtx, cronLogger)
+		}
 
-	termChan := make(chan os.Signal, 1)
-	signal.Notify(termChan, syscall.SIGINT, syscall.SIGTERM)
+		termChan := make(chan os.Signal, 1)
+		signal.Notify(termChan, syscall.SIGINT, syscall.SIGTERM, syscall.SIGUSR2)
 
-	termSig := <-termChan
+		termSig := <-termChan
 
-	logrus.Infof("received %s, shutting down", termSig)
-	notifyExit()
+		if termSig == syscall.SIGUSR2 {
+			logrus.Infof("received %s, reloading crontab", termSig)
+		} else {
+			logrus.Infof("received %s, shutting down", termSig)
+		}
+		notifyExit()
 
-	logrus.Info("waiting for jobs to finish")
-	wg.Wait()
+		logrus.Info("waiting for jobs to finish")
+		wg.Wait()
 
-	logrus.Info("exiting")
+		if termSig != syscall.SIGUSR2 {
+			logrus.Info("exiting")
+			break
+		}
+	}
 }
 
 func readCrontabAtPath(path string) (*crontab.Crontab, error) {