From 0e5137528591ff779a384a8cc7aa5f535222f19e Mon Sep 17 00:00:00 2001
From: Alex Dadgar <alex@hashicorp.com>
Date: Wed, 18 Nov 2015 13:46:43 -0800
Subject: [PATCH] Revert "Make drivers take arguments as a list and not as a
 string"

---
 client/alloc_runner_test.go                  |  6 +--
 client/client_test.go                        |  2 +-
 client/driver/args/args.go                   | 29 ++++++++++----
 client/driver/args/args_test.go              | 41 +++++++++++++++++---
 client/driver/docker.go                      | 13 ++++---
 client/driver/docker_test.go                 | 10 ++---
 client/driver/exec.go                        | 16 +++++---
 client/driver/exec_test.go                   | 16 +++-----
 client/driver/executor/exec_basic.go         |  8 +++-
 client/driver/executor/exec_linux.go         |  7 +++-
 client/driver/executor/test_harness_test.go  |  4 +-
 client/driver/java.go                        | 16 ++++----
 client/driver/java_test.go                   |  3 +-
 client/driver/raw_exec.go                    |  8 +++-
 client/driver/raw_exec_test.go               | 16 +++-----
 client/driver/rkt.go                         | 11 ++++--
 client/driver/rkt_test.go                    |  6 +--
 client/task_runner_test.go                   |  6 +--
 nomad/fsm.go                                 | 11 +++++-
 nomad/mock/mock.go                           |  4 +-
 nomad/rpc.go                                 | 13 ++++++-
 nomad/structs/structs.go                     |  7 ++--
 nomad/timetable_test.go                      |  5 +--
 website/source/docs/drivers/docker.html.md   |  6 +--
 website/source/docs/drivers/exec.html.md     | 22 +++++------
 website/source/docs/drivers/java.html.md     | 20 +++++-----
 website/source/docs/drivers/qemu.html.md     |  9 ++---
 website/source/docs/drivers/raw_exec.html.md | 22 +++++------
 website/source/docs/drivers/rkt.html.md      | 17 ++++----
 29 files changed, 205 insertions(+), 149 deletions(-)

diff --git a/client/alloc_runner_test.go b/client/alloc_runner_test.go
index bc4a7aa4f..15077c76c 100644
--- a/client/alloc_runner_test.go
+++ b/client/alloc_runner_test.go
@@ -65,7 +65,7 @@ func TestAllocRunner_Destroy(t *testing.T) {
 	// Ensure task takes some time
 	task := ar.alloc.Job.TaskGroups[0].Tasks[0]
 	task.Config["command"] = "/bin/sleep"
-	task.Config["args"] = []string{"10"}
+	task.Config["args"] = "10"
 	go ar.Run()
 	start := time.Now()
 
@@ -97,7 +97,7 @@ func TestAllocRunner_Update(t *testing.T) {
 	// Ensure task takes some time
 	task := ar.alloc.Job.TaskGroups[0].Tasks[0]
 	task.Config["command"] = "/bin/sleep"
-	task.Config["args"] = []string{"10"}
+	task.Config["args"] = "10"
 	go ar.Run()
 	defer ar.Destroy()
 	start := time.Now()
@@ -130,7 +130,7 @@ func TestAllocRunner_SaveRestoreState(t *testing.T) {
 	// Ensure task takes some time
 	task := ar.alloc.Job.TaskGroups[0].Tasks[0]
 	task.Config["command"] = "/bin/sleep"
-	task.Config["args"] = []string{"10"}
+	task.Config["args"] = "10"
 	go ar.Run()
 	defer ar.Destroy()
 
diff --git a/client/client_test.go b/client/client_test.go
index 935c63dea..90fecad6b 100644
--- a/client/client_test.go
+++ b/client/client_test.go
@@ -336,7 +336,7 @@ func TestClient_SaveRestoreState(t *testing.T) {
 	alloc1.NodeID = c1.Node().ID
 	task := alloc1.Job.TaskGroups[0].Tasks[0]
 	task.Config["command"] = "/bin/sleep"
-	task.Config["args"] = []string{"10"}
+	task.Config["args"] = "10"
 
 	state := s1.State()
 	err := state.UpsertAllocs(100,
diff --git a/client/driver/args/args.go b/client/driver/args/args.go
index 9e8a9980c..51793bd8b 100644
--- a/client/driver/args/args.go
+++ b/client/driver/args/args.go
@@ -1,6 +1,11 @@
 package args
 
-import "regexp"
+import (
+	"fmt"
+	"regexp"
+
+	"github.com/mattn/go-shellwords"
+)
 
 var (
 	envRe = regexp.MustCompile(`\$({[a-zA-Z0-9_]+}|[a-zA-Z0-9_]+)`)
@@ -8,17 +13,27 @@ var (
 
 // ParseAndReplace takes the user supplied args and a map of environment
 // variables. It replaces any instance of an environment variable in the args
-// with the actual value.
-func ParseAndReplace(args []string, env map[string]string) []string {
-	replaced := make([]string, len(args))
-	for i, arg := range args {
+// with the actual value and does correct splitting of the arg list.
+func ParseAndReplace(args string, env map[string]string) ([]string, error) {
+	// Set up parser.
+	p := shellwords.NewParser()
+	p.ParseEnv = false
+	p.ParseBacktick = false
+
+	parsed, err := p.Parse(args)
+	if err != nil {
+		return nil, fmt.Errorf("Couldn't parse args %v: %v", args, err)
+	}
+
+	replaced := make([]string, len(parsed))
+	for i, arg := range parsed {
 		replaced[i] = ReplaceEnv(arg, env)
 	}
 
-	return replaced
+	return replaced, nil
 }
 
-// ReplaceEnv takes an arg and replaces all occurences of environment variables.
+// replaceEnv takes an arg and replaces all occurences of environment variables.
 // If the variable is found in the passed map it is replaced, otherwise the
 // original string is returned.
 func ReplaceEnv(arg string, env map[string]string) string {
diff --git a/client/driver/args/args_test.go b/client/driver/args/args_test.go
index 5e7cbca4a..4e1d88b59 100644
--- a/client/driver/args/args_test.go
+++ b/client/driver/args/args_test.go
@@ -21,9 +21,12 @@ var (
 )
 
 func TestDriverArgs_ParseAndReplaceInvalidEnv(t *testing.T) {
-	input := []string{"invalid", "$FOO"}
+	input := "invalid $FOO"
 	exp := []string{"invalid", "$FOO"}
-	act := ParseAndReplace(input, envVars)
+	act, err := ParseAndReplace(input, envVars)
+	if err != nil {
+		t.Fatalf("Failed to parse valid input args %v: %v", input, err)
+	}
 
 	if !reflect.DeepEqual(act, exp) {
 		t.Fatalf("ParseAndReplace(%v, %v) returned %#v; want %#v", input, envVars, act, exp)
@@ -31,9 +34,12 @@ func TestDriverArgs_ParseAndReplaceInvalidEnv(t *testing.T) {
 }
 
 func TestDriverArgs_ParseAndReplaceValidEnv(t *testing.T) {
-	input := []string{"nomad_ip", fmt.Sprintf(`"$%v"!`, ipKey)}
+	input := fmt.Sprintf("nomad_ip \\\"$%v\\\"!", ipKey)
 	exp := []string{"nomad_ip", fmt.Sprintf("\"%s\"!", ipVal)}
-	act := ParseAndReplace(input, envVars)
+	act, err := ParseAndReplace(input, envVars)
+	if err != nil {
+		t.Fatalf("Failed to parse valid input args %v: %v", input, err)
+	}
 
 	if !reflect.DeepEqual(act, exp) {
 		t.Fatalf("ParseAndReplace(%v, %v) returned %#v; want %#v", input, envVars, act, exp)
@@ -41,9 +47,32 @@ func TestDriverArgs_ParseAndReplaceValidEnv(t *testing.T) {
 }
 
 func TestDriverArgs_ParseAndReplaceChainedEnv(t *testing.T) {
-	input := []string{"-foo", fmt.Sprintf("$%s$%s", ipKey, portKey)}
+	input := fmt.Sprintf("-foo $%s$%s", ipKey, portKey)
 	exp := []string{"-foo", fmt.Sprintf("%s%s", ipVal, portVal)}
-	act := ParseAndReplace(input, envVars)
+	act, err := ParseAndReplace(input, envVars)
+	if err != nil {
+		t.Fatalf("Failed to parse valid input args %v: %v", input, err)
+	}
+
+	if !reflect.DeepEqual(act, exp) {
+		t.Fatalf("ParseAndReplace(%v, %v) returned %#v; want %#v", input, envVars, act, exp)
+	}
+}
+
+func TestDriverArgs_ParseAndReplaceInvalidArgEscape(t *testing.T) {
+	input := "-c \"echo \"foo\\\" > bar.txt\""
+	if _, err := ParseAndReplace(input, envVars); err == nil {
+		t.Fatalf("ParseAndReplace(%v, %v) should have failed", input, envVars)
+	}
+}
+
+func TestDriverArgs_ParseAndReplaceValidArgEscape(t *testing.T) {
+	input := "-c \"echo \\\"foo\\\" > bar.txt\""
+	exp := []string{"-c", "echo \"foo\" > bar.txt"}
+	act, err := ParseAndReplace(input, envVars)
+	if err != nil {
+		t.Fatalf("Failed to parse valid input args %v: %v", input, err)
+	}
 
 	if !reflect.DeepEqual(act, exp) {
 		t.Fatalf("ParseAndReplace(%v, %v) returned %#v; want %#v", input, envVars, act, exp)
diff --git a/client/driver/docker.go b/client/driver/docker.go
index 4aa97e13b..6fa1af600 100644
--- a/client/driver/docker.go
+++ b/client/driver/docker.go
@@ -35,7 +35,7 @@ type DockerDriverAuth struct {
 type DockerDriverConfig struct {
 	ImageName        string              `mapstructure:"image"`              // Container's Image Name
 	Command          string              `mapstructure:"command"`            // The Command/Entrypoint to run when the container starts up
-	Args             []string            `mapstructure:"args"`               // The arguments to the Command/Entrypoint
+	Args             string              `mapstructure:"args"`               // The arguments to the Command/Entrypoint
 	NetworkMode      string              `mapstructure:"network_mode"`       // The network mode of the container - host, net and none
 	PortMap          []map[string]int    `mapstructure:"port_map"`           // A map of host port labels and the ports exposed on the container
 	Privileged       bool                `mapstructure:"privileged"`         // Flag to run the container in priviledged mode
@@ -293,18 +293,21 @@ func (d *DockerDriver) createContainer(ctx *ExecContext, task *structs.Task, dri
 		config.ExposedPorts = exposedPorts
 	}
 
-	parsedArgs := args.ParseAndReplace(driverConfig.Args, env.Map())
+	parsedArgs, err := args.ParseAndReplace(driverConfig.Args, env.Map())
+	if err != nil {
+		return c, err
+	}
 
 	// If the user specified a custom command to run as their entrypoint, we'll
 	// inject it here.
 	if driverConfig.Command != "" {
 		cmd := []string{driverConfig.Command}
-		if len(driverConfig.Args) != 0 {
+		if driverConfig.Args != "" {
 			cmd = append(cmd, parsedArgs...)
 		}
 		d.logger.Printf("[DEBUG] driver.docker: setting container startup command to: %s", strings.Join(cmd, " "))
 		config.Cmd = cmd
-	} else if len(driverConfig.Args) != 0 {
+	} else if driverConfig.Args != "" {
 		d.logger.Println("[DEBUG] driver.docker: ignoring command arguments because command is not specified")
 	}
 
@@ -428,7 +431,7 @@ func (d *DockerDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandle
 
 			if len(containers) != 1 {
 				log.Printf("[ERR] driver.docker: failed to get id for container %s", config.Name)
-				return nil, fmt.Errorf("Failed to get id for container %s", config.Name)
+				return nil, fmt.Errorf("Failed to get id for container %s: %s", config.Name, err)
 			}
 
 			log.Printf("[INFO] driver.docker: a container with the name %s already exists; will attempt to purge and re-create", config.Name)
diff --git a/client/driver/docker_test.go b/client/driver/docker_test.go
index a61de381c..4c9300579 100644
--- a/client/driver/docker_test.go
+++ b/client/driver/docker_test.go
@@ -137,7 +137,7 @@ func TestDockerDriver_Start_Wait(t *testing.T) {
 		Config: map[string]interface{}{
 			"image":   "redis",
 			"command": "redis-server",
-			"args":    []string{"-v"},
+			"args":    "-v",
 		},
 		Resources: &structs.Resources{
 			MemoryMB: 256,
@@ -190,11 +190,7 @@ func TestDockerDriver_Start_Wait_AllocDir(t *testing.T) {
 		Config: map[string]interface{}{
 			"image":   "redis",
 			"command": "/bin/bash",
-			"args": []string{
-				"-c",
-				fmt.Sprintf(`sleep 1; echo -n %s > $%s/%s`,
-					string(exp), environment.AllocDir, file),
-			},
+			"args":    fmt.Sprintf(`-c "sleep 1; echo -n %s > $%s/%s"`, string(exp), environment.AllocDir, file),
 		},
 		Resources: &structs.Resources{
 			MemoryMB: 256,
@@ -247,7 +243,7 @@ func TestDockerDriver_Start_Kill_Wait(t *testing.T) {
 		Config: map[string]interface{}{
 			"image":   "redis",
 			"command": "/bin/sleep",
-			"args":    []string{"10"},
+			"args":    "10",
 		},
 		Resources: basicResources,
 	}
diff --git a/client/driver/exec.go b/client/driver/exec.go
index a0a136523..1f9e5b7d9 100644
--- a/client/driver/exec.go
+++ b/client/driver/exec.go
@@ -24,10 +24,10 @@ type ExecDriver struct {
 	fingerprint.StaticFingerprinter
 }
 type ExecDriverConfig struct {
-	ArtifactSource string   `mapstructure:"artifact_source"`
-	Checksum       string   `mapstructure:"checksum"`
-	Command        string   `mapstructure:"command"`
-	Args           []string `mapstructure:"args"`
+	ArtifactSource string `mapstructure:"artifact_source"`
+	Checksum       string `mapstructure:"checksum"`
+	Command        string `mapstructure:"command"`
+	Args           string `mapstructure:"args"`
 }
 
 // execHandle is returned from Start/Open as a handle to the PID
@@ -91,8 +91,14 @@ func (d *ExecDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandle,
 	// Get the environment variables.
 	envVars := TaskEnvironmentVariables(ctx, task)
 
+	// Look for arguments
+	var args []string
+	if driverConfig.Args != "" {
+		args = append(args, driverConfig.Args)
+	}
+
 	// Setup the command
-	cmd := executor.Command(command, driverConfig.Args...)
+	cmd := executor.Command(command, args...)
 	if err := cmd.Limit(task.Resources); err != nil {
 		return nil, fmt.Errorf("failed to constrain resources: %s", err)
 	}
diff --git a/client/driver/exec_test.go b/client/driver/exec_test.go
index f5470074a..7e6554e1d 100644
--- a/client/driver/exec_test.go
+++ b/client/driver/exec_test.go
@@ -39,7 +39,7 @@ func TestExecDriver_StartOpen_Wait(t *testing.T) {
 		Name: "sleep",
 		Config: map[string]interface{}{
 			"command": "/bin/sleep",
-			"args":    []string{"5"},
+			"args":    "5",
 		},
 		Resources: basicResources,
 	}
@@ -73,7 +73,7 @@ func TestExecDriver_Start_Wait(t *testing.T) {
 		Name: "sleep",
 		Config: map[string]interface{}{
 			"command": "/bin/sleep",
-			"args":    []string{"2"},
+			"args":    "2",
 		},
 		Resources: basicResources,
 	}
@@ -161,10 +161,7 @@ func TestExecDriver_Start_Artifact_expanded(t *testing.T) {
 		Config: map[string]interface{}{
 			"artifact_source": fmt.Sprintf("https://dl.dropboxusercontent.com/u/47675/jar_thing/%s", file),
 			"command":         "/bin/bash",
-			"args": []string{
-				"-c",
-				fmt.Sprintf(`/bin/sleep 1 && %s`, filepath.Join("$NOMAD_TASK_DIR", file)),
-			},
+			"args":            fmt.Sprintf("-c '/bin/sleep 1 && %s'", filepath.Join("$NOMAD_TASK_DIR", file)),
 		},
 		Resources: basicResources,
 	}
@@ -207,10 +204,7 @@ func TestExecDriver_Start_Wait_AllocDir(t *testing.T) {
 		Name: "sleep",
 		Config: map[string]interface{}{
 			"command": "/bin/bash",
-			"args": []string{
-				"-c",
-				fmt.Sprintf(`sleep 1; echo -n %s > $%s/%s`, string(exp), environment.AllocDir, file),
-			},
+			"args":    fmt.Sprintf("-c \"sleep 1; echo -n %s > $%s/%s\"", string(exp), environment.AllocDir, file),
 		},
 		Resources: basicResources,
 	}
@@ -256,7 +250,7 @@ func TestExecDriver_Start_Kill_Wait(t *testing.T) {
 		Name: "sleep",
 		Config: map[string]interface{}{
 			"command": "/bin/sleep",
-			"args":    []string{"1"},
+			"args":    "1",
 		},
 		Resources: basicResources,
 	}
diff --git a/client/driver/executor/exec_basic.go b/client/driver/executor/exec_basic.go
index 2ef4fbedc..438ae6b92 100644
--- a/client/driver/executor/exec_basic.go
+++ b/client/driver/executor/exec_basic.go
@@ -29,6 +29,7 @@ type BasicExecutor struct {
 	allocDir string
 }
 
+// TODO: Have raw_exec use this as well.
 func NewBasicExecutor() Executor {
 	return &BasicExecutor{}
 }
@@ -62,7 +63,12 @@ func (e *BasicExecutor) Start() error {
 	}
 
 	e.cmd.Path = args.ReplaceEnv(e.cmd.Path, envVars.Map())
-	e.cmd.Args = args.ParseAndReplace(e.cmd.Args, envVars.Map())
+	combined := strings.Join(e.cmd.Args, " ")
+	parsed, err := args.ParseAndReplace(combined, envVars.Map())
+	if err != nil {
+		return err
+	}
+	e.cmd.Args = parsed
 
 	spawnState := filepath.Join(e.allocDir, fmt.Sprintf("%s_%s", e.taskName, "exit_status"))
 	e.spawn = spawn.NewSpawner(spawnState)
diff --git a/client/driver/executor/exec_linux.go b/client/driver/executor/exec_linux.go
index 43c9270e0..14f4f809c 100644
--- a/client/driver/executor/exec_linux.go
+++ b/client/driver/executor/exec_linux.go
@@ -167,7 +167,12 @@ func (e *LinuxExecutor) Start() error {
 	}
 
 	e.cmd.Path = args.ReplaceEnv(e.cmd.Path, envVars.Map())
-	e.cmd.Args = args.ParseAndReplace(e.cmd.Args, envVars.Map())
+	combined := strings.Join(e.cmd.Args, " ")
+	parsed, err := args.ParseAndReplace(combined, envVars.Map())
+	if err != nil {
+		return err
+	}
+	e.cmd.Args = parsed
 
 	spawnState := filepath.Join(e.allocDir, fmt.Sprintf("%s_%s", e.taskName, "exit_status"))
 	e.spawn = spawn.NewSpawner(spawnState)
diff --git a/client/driver/executor/test_harness_test.go b/client/driver/executor/test_harness_test.go
index b5413700c..10cbac371 100644
--- a/client/driver/executor/test_harness_test.go
+++ b/client/driver/executor/test_harness_test.go
@@ -112,7 +112,7 @@ func Executor_Start_Wait(t *testing.T, command buildExecCommand) {
 	expected := "hello world"
 	file := filepath.Join(allocdir.TaskLocal, "output.txt")
 	absFilePath := filepath.Join(taskDir, file)
-	cmd := fmt.Sprintf(`/bin/sleep 1 ; echo -n %v > %v`, expected, file)
+	cmd := fmt.Sprintf(`"%v \"%v\" > %v"`, "/bin/sleep 1 ; echo -n", expected, file)
 	e := command("/bin/bash", "-c", cmd)
 
 	if err := e.Limit(constraint); err != nil {
@@ -190,7 +190,7 @@ func Executor_Open(t *testing.T, command buildExecCommand, newExecutor func() Ex
 	expected := "hello world"
 	file := filepath.Join(allocdir.TaskLocal, "output.txt")
 	absFilePath := filepath.Join(taskDir, file)
-	cmd := fmt.Sprintf(`/bin/sleep 1 ; echo -n %v > %v`, expected, file)
+	cmd := fmt.Sprintf(`"%v \"%v\" > %v"`, "/bin/sleep 1 ; echo -n", expected, file)
 	e := command("/bin/bash", "-c", cmd)
 
 	if err := e.Limit(constraint); err != nil {
diff --git a/client/driver/java.go b/client/driver/java.go
index eb475db32..eb2930a28 100644
--- a/client/driver/java.go
+++ b/client/driver/java.go
@@ -28,10 +28,10 @@ type JavaDriver struct {
 }
 
 type JavaDriverConfig struct {
-	JvmOpts        []string `mapstructure:"jvm_options"`
-	ArtifactSource string   `mapstructure:"artifact_source"`
-	Checksum       string   `mapstructure:"checksum"`
-	Args           []string `mapstructure:"args"`
+	JvmOpts        string `mapstructure:"jvm_options"`
+	ArtifactSource string `mapstructure:"artifact_source"`
+	Checksum       string `mapstructure:"checksum"`
+	Args           string `mapstructure:"args"`
 }
 
 // javaHandle is returned from Start/Open as a handle to the PID
@@ -126,15 +126,15 @@ func (d *JavaDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandle,
 
 	args := []string{}
 	// Look for jvm options
-	if len(driverConfig.JvmOpts) != 0 {
+	if driverConfig.JvmOpts != "" {
 		d.logger.Printf("[DEBUG] driver.java: found JVM options: %s", driverConfig.JvmOpts)
-		args = append(args, driverConfig.JvmOpts...)
+		args = append(args, driverConfig.JvmOpts)
 	}
 
 	// Build the argument list.
 	args = append(args, "-jar", filepath.Join(allocdir.TaskLocal, jarName))
-	if len(driverConfig.Args) != 0 {
-		args = append(args, driverConfig.Args...)
+	if driverConfig.Args != "" {
+		args = append(args, driverConfig.Args)
 	}
 
 	// Setup the command
diff --git a/client/driver/java_test.go b/client/driver/java_test.go
index af6e44d6d..a0c6d3b80 100644
--- a/client/driver/java_test.go
+++ b/client/driver/java_test.go
@@ -51,7 +51,7 @@ func TestJavaDriver_StartOpen_Wait(t *testing.T) {
 		Name: "demo-app",
 		Config: map[string]interface{}{
 			"artifact_source": "https://dl.dropboxusercontent.com/u/47675/jar_thing/demoapp.jar",
-			"jvm_options":     []string{"-Xmx64m", "-Xms32m"},
+			"jvm_options":     "-Xmx2048m -Xms256m",
 			"checksum":        "sha256:58d6e8130308d32e197c5108edd4f56ddf1417408f743097c2e662df0f0b17c8",
 		},
 		Resources: basicResources,
@@ -97,6 +97,7 @@ func TestJavaDriver_Start_Wait(t *testing.T) {
 		Name: "demo-app",
 		Config: map[string]interface{}{
 			"artifact_source": "https://dl.dropboxusercontent.com/u/47675/jar_thing/demoapp.jar",
+			"jvm_options":     "-Xmx2048m -Xms256m",
 			"checksum":        "sha256:58d6e8130308d32e197c5108edd4f56ddf1417408f743097c2e662df0f0b17c8",
 		},
 		Resources: basicResources,
diff --git a/client/driver/raw_exec.go b/client/driver/raw_exec.go
index 5b1d98269..d5202fc39 100644
--- a/client/driver/raw_exec.go
+++ b/client/driver/raw_exec.go
@@ -93,9 +93,15 @@ func (d *RawExecDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandl
 	// Get the environment variables.
 	envVars := TaskEnvironmentVariables(ctx, task)
 
+	// Look for arguments
+	var args []string
+	if driverConfig.Args != "" {
+		args = append(args, driverConfig.Args)
+	}
+
 	// Setup the command
 	cmd := executor.NewBasicExecutor()
-	executor.SetCommand(cmd, command, driverConfig.Args)
+	executor.SetCommand(cmd, command, args)
 	if err := cmd.Limit(task.Resources); err != nil {
 		return nil, fmt.Errorf("failed to constrain resources: %s", err)
 	}
diff --git a/client/driver/raw_exec_test.go b/client/driver/raw_exec_test.go
index 8b6e0c649..1b7a0c8db 100644
--- a/client/driver/raw_exec_test.go
+++ b/client/driver/raw_exec_test.go
@@ -53,7 +53,7 @@ func TestRawExecDriver_StartOpen_Wait(t *testing.T) {
 		Name: "sleep",
 		Config: map[string]interface{}{
 			"command": "/bin/sleep",
-			"args":    []string{"1"},
+			"args":    "1",
 		},
 		Resources: basicResources,
 	}
@@ -151,10 +151,7 @@ func TestRawExecDriver_Start_Artifact_expanded(t *testing.T) {
 		Config: map[string]interface{}{
 			"artifact_source": fmt.Sprintf("https://dl.dropboxusercontent.com/u/47675/jar_thing/%s", file),
 			"command":         "/bin/bash",
-			"args": []string{
-				"-c",
-				fmt.Sprintf(`'/bin/sleep 1 && %s'`, filepath.Join("$NOMAD_TASK_DIR", file)),
-			},
+			"args":            fmt.Sprintf("-c '/bin/sleep 1 && %s'", filepath.Join("$NOMAD_TASK_DIR", file)),
 		},
 		Resources: basicResources,
 	}
@@ -193,7 +190,7 @@ func TestRawExecDriver_Start_Wait(t *testing.T) {
 		Name: "sleep",
 		Config: map[string]interface{}{
 			"command": "/bin/sleep",
-			"args":    []string{"1"},
+			"args":    "1",
 		},
 		Resources: basicResources,
 	}
@@ -235,10 +232,7 @@ func TestRawExecDriver_Start_Wait_AllocDir(t *testing.T) {
 		Name: "sleep",
 		Config: map[string]interface{}{
 			"command": "/bin/bash",
-			"args": []string{
-				"-c",
-				fmt.Sprintf(`sleep 1; echo -n %s > $%s/%s`, string(exp), environment.AllocDir, file),
-			},
+			"args":    fmt.Sprintf(`-c "sleep 1; echo -n %s > $%s/%s"`, string(exp), environment.AllocDir, file),
 		},
 		Resources: basicResources,
 	}
@@ -283,7 +277,7 @@ func TestRawExecDriver_Start_Kill_Wait(t *testing.T) {
 		Name: "sleep",
 		Config: map[string]interface{}{
 			"command": "/bin/sleep",
-			"args":    []string{"1"},
+			"args":    "1",
 		},
 		Resources: basicResources,
 	}
diff --git a/client/driver/rkt.go b/client/driver/rkt.go
index 1fb6e9e06..d09eac1db 100644
--- a/client/driver/rkt.go
+++ b/client/driver/rkt.go
@@ -37,8 +37,8 @@ type RktDriver struct {
 }
 
 type RktDriverConfig struct {
-	ImageName string   `mapstructure:"image"`
-	Args      []string `mapstructure:"args"`
+	ImageName string `mapstructure:"image"`
+	Args      string `mapstructure:"args"`
 }
 
 // rktHandle is returned from Start/Open as a handle to the PID
@@ -150,8 +150,11 @@ func (d *RktDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandle, e
 	}
 
 	// Add user passed arguments.
-	if len(driverConfig.Args) != 0 {
-		parsed := args.ParseAndReplace(driverConfig.Args, envVars.Map())
+	if driverConfig.Args != "" {
+		parsed, err := args.ParseAndReplace(driverConfig.Args, envVars.Map())
+		if err != nil {
+			return nil, err
+		}
 
 		// Need to start arguments with "--"
 		if len(parsed) > 0 {
diff --git a/client/driver/rkt_test.go b/client/driver/rkt_test.go
index 15db27b27..a6b3dfb78 100644
--- a/client/driver/rkt_test.go
+++ b/client/driver/rkt_test.go
@@ -119,7 +119,7 @@ func TestRktDriver_Start_Wait(t *testing.T) {
 			"trust_prefix": "coreos.com/etcd",
 			"image":        "coreos.com/etcd:v2.0.4",
 			"command":      "/etcd",
-			"args":         []string{"--version"},
+			"args":         "--version",
 		},
 	}
 
@@ -160,7 +160,7 @@ func TestRktDriver_Start_Wait_Skip_Trust(t *testing.T) {
 		Config: map[string]interface{}{
 			"image":   "coreos.com/etcd:v2.0.4",
 			"command": "/etcd",
-			"args":    []string{"--version"},
+			"args":    "--version",
 		},
 	}
 
@@ -202,7 +202,7 @@ func TestRktDriver_Start_Wait_Logs(t *testing.T) {
 			"trust_prefix": "coreos.com/etcd",
 			"image":        "coreos.com/etcd:v2.0.4",
 			"command":      "/etcd",
-			"args":         []string{"--version"},
+			"args":         "--version",
 		},
 	}
 
diff --git a/client/task_runner_test.go b/client/task_runner_test.go
index 1ada5060b..f8bc9e466 100644
--- a/client/task_runner_test.go
+++ b/client/task_runner_test.go
@@ -89,7 +89,7 @@ func TestTaskRunner_Destroy(t *testing.T) {
 
 	// Change command to ensure we run for a bit
 	tr.task.Config["command"] = "/bin/sleep"
-	tr.task.Config["args"] = []string{"10"}
+	tr.task.Config["args"] = "10"
 	go tr.Run()
 
 	// Begin the tear down
@@ -128,7 +128,7 @@ func TestTaskRunner_Update(t *testing.T) {
 
 	// Change command to ensure we run for a bit
 	tr.task.Config["command"] = "/bin/sleep"
-	tr.task.Config["args"] = []string{"10"}
+	tr.task.Config["args"] = "10"
 	go tr.Run()
 	defer tr.Destroy()
 	defer tr.ctx.AllocDir.Destroy()
@@ -153,7 +153,7 @@ func TestTaskRunner_SaveRestoreState(t *testing.T) {
 
 	// Change command to ensure we run for a bit
 	tr.task.Config["command"] = "/bin/sleep"
-	tr.task.Config["args"] = []string{"10"}
+	tr.task.Config["args"] = "10"
 	go tr.Run()
 	defer tr.Destroy()
 
diff --git a/nomad/fsm.go b/nomad/fsm.go
index 71c40d68f..21b3538e4 100644
--- a/nomad/fsm.go
+++ b/nomad/fsm.go
@@ -13,6 +13,13 @@ import (
 	"github.com/hashicorp/raft"
 )
 
+var (
+	msgpackHandle = &codec.MsgpackHandle{
+		RawToString: true,
+		WriteExt:    true,
+	}
+)
+
 const (
 	// timeTableGranularity is the granularity of index to time tracking
 	timeTableGranularity = 5 * time.Minute
@@ -321,7 +328,7 @@ func (n *nomadFSM) Restore(old io.ReadCloser) error {
 	defer restore.Abort()
 
 	// Create a decoder
-	dec := codec.NewDecoder(old, structs.MsgpackHandle)
+	dec := codec.NewDecoder(old, msgpackHandle)
 
 	// Read in the header
 	var header snapshotHeader
@@ -405,7 +412,7 @@ func (n *nomadFSM) Restore(old io.ReadCloser) error {
 func (s *nomadSnapshot) Persist(sink raft.SnapshotSink) error {
 	defer metrics.MeasureSince([]string{"nomad", "fsm", "persist"}, time.Now())
 	// Register the nodes
-	encoder := codec.NewEncoder(sink, structs.MsgpackHandle)
+	encoder := codec.NewEncoder(sink, msgpackHandle)
 
 	// Write the header
 	header := snapshotHeader{}
diff --git a/nomad/mock/mock.go b/nomad/mock/mock.go
index 25ca60ef2..12a8484c0 100644
--- a/nomad/mock/mock.go
+++ b/nomad/mock/mock.go
@@ -86,7 +86,7 @@ func Job() *structs.Job {
 						Driver: "exec",
 						Config: map[string]interface{}{
 							"command": "/bin/date",
-							"args":    []string{"+%s"},
+							"args":    "+%s",
 						},
 						Env: map[string]string{
 							"FOO": "bar",
@@ -151,7 +151,7 @@ func SystemJob() *structs.Job {
 						Driver: "exec",
 						Config: map[string]interface{}{
 							"command": "/bin/date",
-							"args":    []string{"+%s"},
+							"args":    "+%s",
 						},
 						Resources: &structs.Resources{
 							CPU:      500,
diff --git a/nomad/rpc.go b/nomad/rpc.go
index e52e258f0..123c35028 100644
--- a/nomad/rpc.go
+++ b/nomad/rpc.go
@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/armon/go-metrics"
+	"github.com/hashicorp/go-msgpack/codec"
 	"github.com/hashicorp/net-rpc-msgpackrpc"
 	"github.com/hashicorp/nomad/nomad/state"
 	"github.com/hashicorp/nomad/nomad/structs"
@@ -52,16 +53,24 @@ const (
 	enqueueLimit = 30 * time.Second
 )
 
+var (
+	// rpcHandle is the MsgpackHandle to be used by both Client and Server codecs.
+	rpcHandle = &codec.MsgpackHandle{
+		// Enables proper encoding of strings within nil interfaces.
+		RawToString: true,
+	}
+)
+
 // NewClientCodec returns a new rpc.ClientCodec to be used to make RPC calls to
 // the Nomad Server.
 func NewClientCodec(conn io.ReadWriteCloser) rpc.ClientCodec {
-	return msgpackrpc.NewCodecFromHandle(true, true, conn, structs.MsgpackHandle)
+	return msgpackrpc.NewCodecFromHandle(true, true, conn, rpcHandle)
 }
 
 // NewServerCodec returns a new rpc.ServerCodec to be used by the Nomad Server
 // to handle rpcs.
 func NewServerCodec(conn io.ReadWriteCloser) rpc.ServerCodec {
-	return msgpackrpc.NewCodecFromHandle(true, true, conn, structs.MsgpackHandle)
+	return msgpackrpc.NewCodecFromHandle(true, true, conn, rpcHandle)
 }
 
 // listen is used to listen for incoming RPC connections
diff --git a/nomad/structs/structs.go b/nomad/structs/structs.go
index 5ff8d8c3b..7fde437cc 100644
--- a/nomad/structs/structs.go
+++ b/nomad/structs/structs.go
@@ -1704,26 +1704,25 @@ func (p *PlanResult) FullCommit(plan *Plan) (bool, int, int) {
 }
 
 // msgpackHandle is a shared handle for encoding/decoding of structs
-var MsgpackHandle = func() *codec.MsgpackHandle {
+var msgpackHandle = func() *codec.MsgpackHandle {
 	h := &codec.MsgpackHandle{RawToString: true}
 
 	// Sets the default type for decoding a map into a nil interface{}.
 	// This is necessary in particular because we store the driver configs as a
 	// nil interface{}.
 	h.MapType = reflect.TypeOf(map[string]interface{}(nil))
-	h.SliceType = reflect.TypeOf([]string{})
 	return h
 }()
 
 // Decode is used to decode a MsgPack encoded object
 func Decode(buf []byte, out interface{}) error {
-	return codec.NewDecoder(bytes.NewReader(buf), MsgpackHandle).Decode(out)
+	return codec.NewDecoder(bytes.NewReader(buf), msgpackHandle).Decode(out)
 }
 
 // Encode is used to encode a MsgPack object with type prefix
 func Encode(t MessageType, msg interface{}) ([]byte, error) {
 	var buf bytes.Buffer
 	buf.WriteByte(uint8(t))
-	err := codec.NewEncoder(&buf, MsgpackHandle).Encode(msg)
+	err := codec.NewEncoder(&buf, msgpackHandle).Encode(msg)
 	return buf.Bytes(), err
 }
diff --git a/nomad/timetable_test.go b/nomad/timetable_test.go
index a76446a13..3a771d6fa 100644
--- a/nomad/timetable_test.go
+++ b/nomad/timetable_test.go
@@ -7,7 +7,6 @@ import (
 	"time"
 
 	"github.com/hashicorp/go-msgpack/codec"
-	"github.com/hashicorp/nomad/nomad/structs"
 )
 
 func TestTimeTable(t *testing.T) {
@@ -105,14 +104,14 @@ func TestTimeTable_SerializeDeserialize(t *testing.T) {
 	tt.Witness(50, plusHour)
 
 	var buf bytes.Buffer
-	enc := codec.NewEncoder(&buf, structs.MsgpackHandle)
+	enc := codec.NewEncoder(&buf, msgpackHandle)
 
 	err := tt.Serialize(enc)
 	if err != nil {
 		t.Fatalf("err: %v", err)
 	}
 
-	dec := codec.NewDecoder(&buf, structs.MsgpackHandle)
+	dec := codec.NewDecoder(&buf, msgpackHandle)
 
 	tt2 := NewTimeTable(time.Second, time.Minute)
 	err = tt2.Deserialize(dec)
diff --git a/website/source/docs/drivers/docker.html.md b/website/source/docs/drivers/docker.html.md
index a50bc1cec..d1c6bafbe 100644
--- a/website/source/docs/drivers/docker.html.md
+++ b/website/source/docs/drivers/docker.html.md
@@ -19,13 +19,13 @@ and cleaning up after containers.
 The `docker` driver supports the following configuration in the job
 specification:
 
-* `image` - The Docker image to run. The image may include a tag or
+* `image` - (Required) The Docker image to run. The image may include a tag or
   custom URL. By default it will be fetched from Docker Hub.
 
 * `command` - (Optional) The command to run when starting the container.
 
-* `args` - (Optional) A list of arguments to the optional `command`. If no
-  `command` is present, `args` are ignored.
+* `args` - (Optional) Arguments to the optional `command`. If no `command` is
+  present, `args` are ignored.
 
 * `network_mode` - (Optional) The network mode to be used for the container. In
   order to support userspace networking plugins in Docker 1.9 this accepts any
diff --git a/website/source/docs/drivers/exec.html.md b/website/source/docs/drivers/exec.html.md
index 3d921aa6d..f897b1ea4 100644
--- a/website/source/docs/drivers/exec.html.md
+++ b/website/source/docs/drivers/exec.html.md
@@ -20,19 +20,15 @@ scripts or other wrappers which provide higher level features.
 
 The `exec` driver supports the following configuration in the job spec:
 
-* `command` - The command to execute. Must be provided.
-
-* `artifact_source` – (Optional) Source location of an executable artifact. Must
-  be accessible from the Nomad client. If you specify an `artifact_source` to be
-  executed, you must reference it in the `command` as show in the examples below
-
-* `checksum` - (Optional) The checksum type and value for the `artifact_source`
-  image.  The format is `type:value`, where type is any of `md5`, `sha1`,
-  `sha256`, or `sha512`, and the value is the computed checksum. If a checksum
-  is supplied and does not match the downloaded artifact, the driver will fail
-  to start
-
-* `args` - (Optional) A list of arguments to the `command`.
+* `command` - (Required) The command to execute. Must be provided.
+* `artifact_source` – (Optional) Source location of an executable artifact. Must be accessible
+from the Nomad client. If you specify an `artifact_source` to be executed, you
+must reference it in the `command` as show in the examples below
+* `checksum` - **(Optional)** The checksum type and value for the `artifact_source` image.
+The format is `type:value`, where type is any of `md5`, `sha1`, `sha256`, or `sha512`,
+and the value is the computed checksum. If a checksum is supplied and does not
+match the downloaded artifact, the driver will fail to start
+* `args` - The argument list to the command, space seperated. Optional.
 
 ## Client Requirements
 
diff --git a/website/source/docs/drivers/java.html.md b/website/source/docs/drivers/java.html.md
index 45baacb72..f2bbd2b76 100644
--- a/website/source/docs/drivers/java.html.md
+++ b/website/source/docs/drivers/java.html.md
@@ -18,19 +18,17 @@ HTTP from the Nomad client.
 
 The `java` driver supports the following configuration in the job spec:
 
-* `artifact_source` - The hosted location of the source Jar file. Must be
-  accessible from the Nomad client
+* `artifact_source` - **(Required)** The hosted location of the source Jar file. Must be accessible
+from the Nomad client
+* `checksum` - **(Optional)** The checksum type and value for the `artifact_source` image.
+The format is `type:value`, where type is any of `md5`, `sha1`, `sha256`, or `sha512`,
+and the value is the computed checksum. If a checksum is supplied and does not
+match the downloaded artifact, the driver will fail to start
 
-* `checksum` - (Optional) The checksum type and value for the `artifact_source`
-  image.  The format is `type:value`, where type is any of `md5`, `sha1`,
-  `sha256`, or `sha512`, and the value is the computed checksum. If a checksum
-  is supplied and does not match the downloaded artifact, the driver will fail
-  to start
+* `args` - **(Optional)** The argument list for the `java` command, space separated.
 
-* `args` - (Optional) A list of arguments to the `java` command.
-
-* `jvm_options` - (Optional) A list of JVM options to be passed while invoking
-  java. These options are passed not validated in any way in Nomad.
+* `jvm_options` - **(Optional)** JVM options to be passed while invoking java. These options
+  are passed not validated in any way in Nomad.
 
 ## Client Requirements
 
diff --git a/website/source/docs/drivers/qemu.html.md b/website/source/docs/drivers/qemu.html.md
index d329c7a8e..84909e331 100644
--- a/website/source/docs/drivers/qemu.html.md
+++ b/website/source/docs/drivers/qemu.html.md
@@ -23,19 +23,16 @@ The `Qemu` driver can execute any regular `qemu` image (e.g. `qcow`, `img`,
 
 The `Qemu` driver supports the following configuration in the job spec:
 
-* `artifact_source` - The hosted location of the source Qemu image. Must be accessible
+* `artifact_source` - **(Required)** The hosted location of the source Qemu image. Must be accessible
   from the Nomad client, via HTTP.
-
-* `checksum` - (Optional) The checksum type and value for the `artifact_source` image.
+* `checksum` - **(Optional)** The checksum type and value for the `artifact_source` image.
   The format is `type:value`, where type is any of `md5`, `sha1`, `sha256`, or `sha512`,
   and the value is the computed checksum. If a checksum is supplied and does not
   match the downloaded artifact, the driver will fail to start
-
 * `accelerator` - (Optional) The type of accelerator to use in the invocation.
   If the host machine has `Qemu` installed with KVM support, users can specify
   `kvm` for the `accelerator`. Default is `tcg`
-
-* `port_map` - (Optional) A `map[string]int` that maps port labels to ports
+* `port_map` - **(Optional)** A `map[string]int` that maps port labels to ports
   on the guest. This forwards the host port to the guest vm. For example,
   `port_map { db = 6539 }` would forward the host port with label `db` to the
   guest vm's port 6539.
diff --git a/website/source/docs/drivers/raw_exec.html.md b/website/source/docs/drivers/raw_exec.html.md
index c76825f25..2dc741887 100644
--- a/website/source/docs/drivers/raw_exec.html.md
+++ b/website/source/docs/drivers/raw_exec.html.md
@@ -18,19 +18,15 @@ As such, it should be used with extreme care and is disabled by default.
 
 The `raw_exec` driver supports the following configuration in the job spec:
 
-* `command` - The command to execute. Must be provided.
-
-* `artifact_source` – (Optional) Source location of an executable artifact. Must
-  be accessible from the Nomad client. If you specify an `artifact_source` to be
-  executed, you must reference it in the `command` as show in the examples below
-
-* `checksum` - (Optional) The checksum type and value for the `artifact_source`
-  image.  The format is `type:value`, where type is any of `md5`, `sha1`,
-  `sha256`, or `sha512`, and the value is the computed checksum. If a checksum
-  is supplied and does not match the downloaded artifact, the driver will fail
-  to start
-
-* `args` - (Optional) A list of arguments to the `command`.
+* `command` - (Required) The command to execute. Must be provided.
+* `artifact_source` – (Optional) Source location of an executable artifact. Must be accessible
+from the Nomad client. If you specify an `artifact_source` to be executed, you
+must reference it in the `command` as show in the examples below
+* `checksum` - **(Optional)** The checksum type and value for the `artifact_source` image.
+The format is `type:value`, where type is any of `md5`, `sha1`, `sha256`, or `sha512`,
+and the value is the computed checksum. If a checksum is supplied and does not
+match the downloaded artifact, the driver will fail to start
+* `args` - The argument list to the command, space seperated. Optional.
 
 ## Client Requirements
 
diff --git a/website/source/docs/drivers/rkt.html.md b/website/source/docs/drivers/rkt.html.md
index 7ce3e1a49..ddbb76601 100644
--- a/website/source/docs/drivers/rkt.html.md
+++ b/website/source/docs/drivers/rkt.html.md
@@ -20,16 +20,13 @@ being marked as experimental and should be used with care.
 
 The `rkt` driver supports the following configuration in the job spec:
 
-* `image` - The image to run which may be specified by name, hash, ACI address
-  or docker registry.
-
-* `command` - (Optional) A command to execute on the ACI.
-
-* `args` - (Optional) A list of arguments to the image.
-
-* `trust_prefix` - (Optional) The trust prefix to be passed to rkt. Must be
-  reachable from the box running the nomad agent. If not specified, the image is
-  run without verifying the image signature.
+* `trust_prefix` - **(Optional)** The trust prefix to be passed to rkt. Must be reachable from
+the box running the nomad agent. If not specified, the image is run without
+verifying the image signature.
+* `image` - **(Required)** The image to run which may be specified by name,
+hash, ACI address or docker registry.
+* `command` - **(Optional**) A command to execute on the ACI.
+* `args` - **(Optional**) A string of args to pass into the image.
 
 ## Task Directories