From 82b176453168d552134e1531fa217009dfe497ce Mon Sep 17 00:00:00 2001
From: Mahmood Ali <mahmood@hashicorp.com>
Date: Thu, 8 Nov 2018 22:14:27 -0500
Subject: [PATCH] handle nil resources limits

Config may not express resource constraints on the job!
---
 drivers/exec/driver.go | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/drivers/exec/driver.go b/drivers/exec/driver.go
index eaf823a64..8c5cfbeab 100644
--- a/drivers/exec/driver.go
+++ b/drivers/exec/driver.go
@@ -303,14 +303,10 @@ func (d *Driver) StartTask(cfg *drivers.TaskConfig) (*drivers.TaskHandle, *cstru
 		Env:            cfg.EnvList(),
 		User:           cfg.User,
 		ResourceLimits: true,
-		Resources: &executor.Resources{
-			CPU:      cfg.Resources.NomadResources.CPU,
-			MemoryMB: cfg.Resources.NomadResources.MemoryMB,
-			DiskMB:   cfg.Resources.NomadResources.DiskMB,
-		},
-		TaskDir:    cfg.TaskDir().Dir,
-		StdoutPath: cfg.StdoutPath,
-		StderrPath: cfg.StderrPath,
+		Resources:      toExecResources(cfg.Resources),
+		TaskDir:        cfg.TaskDir().Dir,
+		StdoutPath:     cfg.StdoutPath,
+		StderrPath:     cfg.StderrPath,
 	}
 
 	ps, err := exec.Launch(execCmd)
@@ -348,6 +344,19 @@ func (d *Driver) StartTask(cfg *drivers.TaskConfig) (*drivers.TaskHandle, *cstru
 	return handle, nil, nil
 }
 
+func toExecResources(resources *drivers.Resources) *executor.Resources {
+	if resources == nil || resources.NomadResources == nil {
+		return nil
+	}
+
+	return &executor.Resources{
+		CPU:      resources.NomadResources.CPU,
+		MemoryMB: resources.NomadResources.MemoryMB,
+		DiskMB:   resources.NomadResources.DiskMB,
+	}
+
+}
+
 func (d *Driver) WaitTask(ctx context.Context, taskID string) (<-chan *drivers.ExitResult, error) {
 	handle, ok := d.tasks.Get(taskID)
 	if !ok {