Plugin config parsing

command/agent/config-test-fixtures/basic.hcl

@@ -190,3 +190,17 @@ autopilot {
 	server_stabilization_time = "23057s"
 	enable_custom_upgrades = true
 }
+plugin "docker" {
+  args = ["foo", "bar"]
+  config {
+    foo = "bar"
+    nested {
+      bam = 2
+    }
+  }
+}
+plugin "exec" {
+  config {
+    foo = true
+  }
+}

command/agent/config.go

@@ -133,6 +133,9 @@ type Config struct {
 
 	// Autopilot contains the configuration for Autopilot behavior.
 	Autopilot *config.AutopilotConfig `mapstructure:"autopilot"`
+
+	// Plugins is the set of configured plugins
+	Plugins []*config.PluginConfig `hcl:"plugin,expand"`
 }
 
 // ClientConfig is configuration specific to the client mode
@@ -855,6 +858,16 @@ func (c *Config) Merge(b *Config) *Config {
 		result.Autopilot = result.Autopilot.Merge(b.Autopilot)
 	}
 
+	if len(result.Plugins) == 0 && len(b.Plugins) != 0 {
+		copy := make([]*config.PluginConfig, len(b.Plugins))
+		for i, v := range b.Plugins {
+			copy[i] = v.Copy()
+		}
+		result.Plugins = copy
+	} else if len(b.Plugins) != 0 {
+		result.Plugins = config.PluginConfigSetMerge(result.Plugins, b.Plugins)
+	}
+
 	// Merge config files lists
 	result.Files = append(result.Files, b.Files...)
 

command/agent/config_parse.go

@@ -101,6 +101,7 @@ func parseConfig(result *Config, list *ast.ObjectList) error {
 		"acl",
 		"sentinel",
 		"autopilot",
+		"plugin",
 	}
 	if err := helper.CheckHCLKeys(list, valid); err != nil {
 		return multierror.Prefix(err, "config:")
@@ -125,6 +126,7 @@ func parseConfig(result *Config, list *ast.ObjectList) error {
 	delete(m, "acl")
 	delete(m, "sentinel")
 	delete(m, "autopilot")
+	delete(m, "plugin")
 
 	// Decode the rest
 	if err := mapstructure.WeakDecode(m, result); err != nil {
@@ -215,6 +217,13 @@ func parseConfig(result *Config, list *ast.ObjectList) error {
 		}
 	}
 
+	// Parse Plugin configs
+	if o := list.Filter("plugin"); len(o.Items) > 0 {
+		if err := parsePlugins(&result.Plugins, o); err != nil {
+			return multierror.Prefix(err, "plugin->")
+		}
+	}
+
 	// Parse out http_api_response_headers fields. These are in HCL as a list so
 	// we need to iterate over them and merge them.
 	if headersO := list.Filter("http_api_response_headers"); len(headersO.Items) > 0 {
@@ -986,3 +995,38 @@ func parseAutopilot(result **config.AutopilotConfig, list *ast.ObjectList) error
 	*result = autopilotConfig
 	return nil
 }
+
+func parsePlugins(result *[]*config.PluginConfig, list *ast.ObjectList) error {
+	listLen := len(list.Items)
+	plugins := make([]*config.PluginConfig, listLen)
+
+	// Check for invalid keys
+	valid := []string{
+		"args",
+		"config",
+	}
+
+	for i := 0; i < listLen; i++ {
+		// Get the current plugin object
+		listVal := list.Items[i]
+
+		if err := helper.CheckHCLKeys(listVal.Val, valid); err != nil {
+			return fmt.Errorf("invalid keys in plugin config %d: %v", i+1, err)
+		}
+
+		// Ensure there is a key
+		if len(listVal.Keys) != 1 {
+			return fmt.Errorf("plugin config %d doesn't incude a name key", i+1)
+		}
+
+		var plugin config.PluginConfig
+		if err := hcl.DecodeObject(&plugin, listVal); err != nil {
+			return fmt.Errorf("error decoding plugin config %d: %v", i+1, err)
+		}
+
+		plugins[i] = &plugin
+	}
+
+	*result = plugins
+	return nil
+}

command/agent/config_parse_test.go

@@ -215,6 +215,26 @@ func TestConfig_Parse(t *testing.T) {
 					DisableUpgradeMigration: &trueValue,
 					EnableCustomUpgrades:    &trueValue,
 				},
+				Plugins: []*config.PluginConfig{
+					{
+						Name: "docker",
+						Args: []string{"foo", "bar"},
+						Config: map[string]interface{}{
+							"foo": "bar",
+							"nested": []map[string]interface{}{
+								{
+									"bam": 2,
+								},
+							},
+						},
+					},
+					{
+						Name: "exec",
+						Config: map[string]interface{}{
+							"foo": true,
+						},
+					},
+				},
 			},
 			false,
 		},
@@ -264,19 +284,19 @@ func TestConfig_Parse(t *testing.T) {
 				SyslogFacility:            "",
 				DisableUpdateCheck:        nil,
 				DisableAnonymousSignature: false,
-				Consul:                 nil,
-				Vault:                  nil,
-				TLSConfig:              nil,
-				HTTPAPIResponseHeaders: nil,
-				Sentinel:               nil,
+				Consul:                    nil,
+				Vault:                     nil,
+				TLSConfig:                 nil,
+				HTTPAPIResponseHeaders:    nil,
+				Sentinel:                  nil,
 			},
 			false,
 		},
 	}
 
 	for _, tc := range cases {
-		require := require.New(t)
 		t.Run(tc.File, func(t *testing.T) {
+			require := require.New(t)
 			path, err := filepath.Abs(filepath.Join("./config-test-fixtures", tc.File))
 			if err != nil {
 				t.Fatalf("file: %s\n\n%s", tc.File, err)

command/agent/config_test.go

@@ -175,6 +175,15 @@ func TestConfig_Merge(t *testing.T) {
 			DisableUpgradeMigration: &falseValue,
 			EnableCustomUpgrades:    &falseValue,
 		},
+		Plugins: []*config.PluginConfig{
+			{
+				Name: "docker",
+				Args: []string{"foo"},
+				Config: map[string]interface{}{
+					"bar": 1,
+				},
+			},
+		},
 	}
 
 	c3 := &Config{
@@ -341,6 +350,22 @@ func TestConfig_Merge(t *testing.T) {
 			DisableUpgradeMigration: &trueValue,
 			EnableCustomUpgrades:    &trueValue,
 		},
+		Plugins: []*config.PluginConfig{
+			{
+				Name: "docker",
+				Args: []string{"bam"},
+				Config: map[string]interface{}{
+					"baz": 2,
+				},
+			},
+			{
+				Name: "exec",
+				Args: []string{"arg"},
+				Config: map[string]interface{}{
+					"config": true,
+				},
+			},
+		},
 	}
 
 	result := c0.Merge(c1)

nomad/structs/config/plugins.go

@@ -0,0 +1,75 @@
+package config
+
+import "github.com/mitchellh/copystructure"
+
+// PluginConfig is used to configure a plugin explicitly
+type PluginConfig struct {
+	Name   string                 `hcl:",key"`
+	Args   []string               `hcl:"args"`
+	Config map[string]interface{} `hcl:"config"`
+}
+
+func (p *PluginConfig) Merge(o *PluginConfig) *PluginConfig {
+	m := *p
+
+	if len(o.Name) != 0 {
+		m.Name = o.Name
+	}
+	if len(o.Args) != 0 {
+		m.Args = o.Args
+	}
+	if len(o.Config) != 0 {
+		m.Config = o.Config
+	}
+
+	return m.Copy()
+}
+
+func (p *PluginConfig) Copy() *PluginConfig {
+	c := *p
+	if i, err := copystructure.Copy(p.Config); err != nil {
+		panic(err.Error())
+	} else {
+		c.Config = i.(map[string]interface{})
+	}
+	return &c
+}
+
+// PluginConfigSetMerge merges to sets of plugin configs. For plugins with the
+// same name, the configs are merged.
+func PluginConfigSetMerge(first, second []*PluginConfig) []*PluginConfig {
+	findex := make(map[string]*PluginConfig, len(first))
+	for _, p := range first {
+		findex[p.Name] = p
+	}
+
+	sindex := make(map[string]*PluginConfig, len(second))
+	for _, p := range second {
+		sindex[p.Name] = p
+	}
+
+	var out []*PluginConfig
+
+	// Go through the first set and merge any value that exist in both
+	for pluginName, original := range findex {
+		second, ok := sindex[pluginName]
+		if !ok {
+			out = append(out, original.Copy())
+			continue
+		}
+
+		out = append(out, original.Merge(second))
+	}
+
+	// Go through the second set and add any value that didn't exist in both
+	for pluginName, plugin := range sindex {
+		_, ok := findex[pluginName]
+		if ok {
+			continue
+		}
+
+		out = append(out, plugin)
+	}
+
+	return out
+}

nomad/structs/config/plugins_test.go

@@ -0,0 +1,101 @@
+package config
+
+import (
+	"sort"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPluginConfig_Merge(t *testing.T) {
+	t.Parallel()
+	require := require.New(t)
+	a := &PluginConfig{
+		Name: "foo",
+		Args: []string{"bar"},
+		Config: map[string]interface{}{
+			"baz": true,
+		},
+	}
+
+	e1 := &PluginConfig{
+		Name: "replaced",
+		Args: []string{"bar"},
+		Config: map[string]interface{}{
+			"baz": true,
+		},
+	}
+	o1 := a.Merge(&PluginConfig{Name: "replaced"})
+	require.Equal(e1, o1)
+
+	e2 := &PluginConfig{
+		Name: "foo",
+		Args: []string{"replaced", "another"},
+		Config: map[string]interface{}{
+			"baz": true,
+		},
+	}
+	o2 := a.Merge(&PluginConfig{
+		Args: []string{"replaced", "another"},
+	})
+	require.Equal(e2, o2)
+
+	e3 := &PluginConfig{
+		Name: "foo",
+		Args: []string{"bar"},
+		Config: map[string]interface{}{
+			"replaced": 1,
+		},
+	}
+	o3 := a.Merge(&PluginConfig{
+		Config: map[string]interface{}{
+			"replaced": 1,
+		},
+	})
+	require.Equal(e3, o3)
+}
+
+func TestPluginConfigSet_Merge(t *testing.T) {
+	t.Parallel()
+	require := require.New(t)
+
+	a := &PluginConfig{
+		Name: "a",
+		Args: []string{"a1"},
+		Config: map[string]interface{}{
+			"a1": true,
+		},
+	}
+	b1 := &PluginConfig{
+		Name: "b",
+		Args: []string{"b1"},
+		Config: map[string]interface{}{
+			"b1": true,
+		},
+	}
+	b2 := &PluginConfig{
+		Name: "b",
+		Args: []string{"b2"},
+		Config: map[string]interface{}{
+			"b2": true,
+		},
+	}
+	c := &PluginConfig{
+		Name: "c",
+		Args: []string{"c"},
+		Config: map[string]interface{}{
+			"c1": true,
+		},
+	}
+
+	s1 := []*PluginConfig{a, b1}
+	s2 := []*PluginConfig{b2, c}
+
+	out := PluginConfigSetMerge(s1, s2)
+	sort.Slice(out, func(i, j int) bool {
+		return out[i].Name < out[j].Name
+	})
+
+	expected := []*PluginConfig{a, b2, c}
+	require.EqualValues(expected, out)
+}