Merge pull request #10 from viafintech/feature/add-fail-on-lock-wait-…

…time-expired

Add support for a non 0 exit code if lock was never retrieved

README.md

@@ -19,6 +19,8 @@ Use `cronlocker --help` to get the following output:
 Usage of ./cronlocker:
   -endpoint string
       endpoint (default "http://localhost:8500")
+  -failwithoutlock
+      Exists with status code 1 if the lock was not received within lockwaittime
   -key string
       key to monitor, e.g. cronjobs/any_service/cron_name (default "none")
   -lockwaittime int

command_locker.go

@@ -3,31 +3,40 @@ package main
 import (
 	"bytes"
 	"context"
+	"errors"
 	"net/url"
 	"os/exec"
 	"time"
 
 	"github.com/hashicorp/consul/api"
 )
 
+var errLockWaitTimeExpired = errors.New("wait time for acquiring the lock expired")
+
+// ConsulCommandLocker is an implementation of a command locker for consul,
+// responsible for acquiring a distributed lock and executing a command
 type ConsulCommandLocker struct {
-	apiClient    *api.Client
-	lockWaitTime time.Duration
-	minLockTime  time.Duration
-	maxExecTime  time.Duration
+	apiClient                *api.Client
+	lockWaitTime             time.Duration
+	minLockTime              time.Duration
+	maxExecTime              time.Duration
+	failOnLockWaitExpiration bool
 }
 
+// NewConsulCommandLocker initializes a new ConsulCommandlocker
 func NewConsulCommandLocker(
 	endpoint string,
 	token string,
 	lockWaitTime time.Duration,
 	minLockTime time.Duration,
 	maxExecTime time.Duration,
+	failOnLockWaitExpiration bool,
 ) (*ConsulCommandLocker, error) {
 	ccl := &ConsulCommandLocker{
-		lockWaitTime: lockWaitTime,
-		minLockTime:  minLockTime,
-		maxExecTime:  maxExecTime,
+		lockWaitTime:             lockWaitTime,
+		minLockTime:              minLockTime,
+		maxExecTime:              maxExecTime,
+		failOnLockWaitExpiration: failOnLockWaitExpiration,
 	}
 
 	url, err := url.Parse(endpoint)
@@ -53,6 +62,7 @@ func NewConsulCommandLocker(
 	return ccl, nil
 }
 
+// LockAndExecute takes a lock key and executes the command
 func (ccl *ConsulCommandLocker) LockAndExecute(key, command string) (string, error) {
 	lockOpts := &api.LockOptions{
 		Key:          key,
@@ -75,6 +85,10 @@ func (ccl *ConsulCommandLocker) LockAndExecute(key, command string) (string, err
 	// The lock was not acquired if lock channel is empty
 	// Therefore we can simply return
 	if lockCh == nil {
+		if ccl.failOnLockWaitExpiration {
+			return "", errLockWaitTimeExpired
+		}
+
 		return "Nothing was executed\n", nil
 	}
 

command_locker_test.go

@@ -45,6 +45,7 @@ func TestConsulCommandLockerLockAndExecute(t *testing.T) {
 		300*time.Millisecond,
 		time.Millisecond,
 		0,
+		false,
 	)
 
 	for _, c := range cases {
@@ -85,6 +86,7 @@ func TestConsulCommandLockerMinimumLockAndExecuteTime(t *testing.T) {
 		300*time.Millisecond,
 		500*time.Millisecond,
 		0,
+		false,
 	)
 
 	startTime := time.Now()
@@ -103,13 +105,41 @@ func TestConsulCommandLockerMaximumExecutionTime(t *testing.T) {
 		100*time.Millisecond,
 		300*time.Millisecond,
 		500*time.Millisecond,
+		false,
 	)
 
 	startTime := time.Now()
 
-	commandLocker.LockAndExecute("test/cron/service/min_time_job", "sleep 5")
+	commandLocker.LockAndExecute("test/cron/service/max_time_job", "sleep 5")
 
 	if time.Since(startTime) > 700*time.Millisecond {
 		t.Errorf("Locker did not abort after the maximum execution time was reached")
 	}
 }
+
+func TestConsulCommandLockerFailOnLockWaitTimeExpired(t *testing.T) {
+	commandLocker, _ := NewConsulCommandLocker(
+		testutils.CONSULURI,
+		"", // blank token
+		300*time.Millisecond,
+		500*time.Millisecond,
+		0,
+		true,
+	)
+
+	go func() {
+		commandLocker.LockAndExecute("test/cron/service/lock_wait_time_job", "sleep 10")
+	}()
+
+	time.Sleep(100 * time.Millisecond)
+
+	output, err := commandLocker.LockAndExecute("test/cron/service/lock_wait_time_job", "sleep 2")
+
+	if output != "" {
+		t.Errorf("Expected no output but received: %s", output)
+	}
+
+	if err != errLockWaitTimeExpired {
+		t.Errorf("Expected to received errLockWaitTimeExpired, but received: %+v", err)
+	}
+}

main.go

@@ -14,6 +14,11 @@ var (
 		500,
 		"Configures the wait time for a lock in milliseconds",
 	)
+	failOnLockWaitExpiration = flag.Bool(
+		"failwithoutlock",
+		false,
+		"Exists with status code 1 if the lock was not received within lockwaittime",
+	)
 	minLockTimeMS = flag.Int(
 		"minlocktime",
 		5000,
@@ -52,6 +57,7 @@ func main() {
 		time.Duration(*lockWaitTimeMS)*time.Millisecond,
 		time.Duration(*minLockTimeMS)*time.Millisecond,
 		time.Duration(*maxExecutionTimeMS)*time.Millisecond,
+		*failOnLockWaitExpiration,
 	)
 	if err != nil {
 		log.Fatalf("%v", err)