Add command to check lockfile (closes #67)

main.go

@@ -40,7 +40,7 @@ func main() {
 
 	lockFile, lockErr := LockFileFromOptions(options)
 	if lockErr != nil {
-		log.Printf("Could not get LockFile: %s", lockErr.Error())
+		log.Printf("Error: %s", lockErr.Error())
 		os.Exit(3)
 	}
 
@@ -106,6 +106,17 @@ func processFlags() Options {
 		os.Exit(0)
 	}
 
+	if options.checkLock != "" {
+		lockFile, lockErr := LockFileFromOptions(options)
+		if lockErr != nil {
+			log.Printf("Error: %s found, previous run failed or is ongoing", lockFile.Path)
+			os.Exit(3)
+		} else {
+			log.Printf("Success: %s does not exist", lockFile.Path)
+			os.Exit(0)
+		}
+	}
+
 	if options.playbook == "" {
 		fmt.Println("required flag not defined: -playbook")
 		os.Exit(2)
@@ -161,6 +172,9 @@ func LockFileFromOptions(options Options) (*LockFile, error) {
 	} else if options.softLock != "" {
 		lockPath = options.softLock
 		isSoftLock = true
+	} else if options.checkLock != "" {
+		lockPath = options.checkLock
+		isSoftLock = false
 	} else {
 		// no-op
 		return nil, nil

options.go

@@ -45,6 +45,7 @@ type Options struct {
 	consul    string
 	lock      string
 	softLock  string
+	checkLock string
 	variables CLIVariables
 }
 
@@ -65,6 +66,7 @@ func (o *Options) GetFlagSet() *flag.FlagSet {
 	fs.StringVar(&(o.consul), "consul", "", "The address of a consul server with playbooks and SQL files stored in KV pairs")
 	fs.StringVar(&(o.lock), "lock", "", "Optional argument which checks and sets a lockfile to ensure this run is a singleton. Deletes lock on run completing successfully")
 	fs.StringVar(&(o.softLock), "softLock", "", "Optional argument, like '-lock' but the lockfile will be deleted even if the run fails")
+	fs.StringVar(&(o.checkLock), "checkLock", "", "Checks whether the lockfile already exists")
 	// TODO: add format flag if/when we support TOML
 
 	return fs