Add an `Extras` field on the compose config types.

That field is automaticaly populated with any `x-*` field in the yaml.
And marshalling the compose config struct put them back into place.

This make it possible to get those extra fields without re-inventing
the wheel (i.e. reimplementing 80% of the `cli/compose/*` packages.

Signed-off-by: Vincent Demeester <vincent@sbr.pm>

cli/compose/loader/full-example.yml

@@ -278,6 +278,8 @@ services:
           size: 10000
 
     working_dir: /code
+    x-bar: baz
+    x-foo: bar
 
 networks:
   # Entries can be null, which specifies simply that a network
@@ -318,6 +320,8 @@ networks:
     # can be referred to within this file as "other-external-network"
     external:
       name: my-cool-network
+    x-bar: baz
+    x-foo: bar
 
 volumes:
   # Entries can be null, which specifies simply that a volume
@@ -361,6 +365,8 @@ volumes:
     # can be referred to within this file as "external-volume3"
     name: this-is-volume3
     external: true
+    x-bar: baz
+    x-foo: bar
 
 configs:
   config1:
@@ -374,6 +380,8 @@ configs:
     external: true
   config4:
     name: foo
+    x-bar: baz
+    x-foo: bar
 
 secrets:
   secret1:
@@ -387,3 +395,10 @@ secrets:
     external: true
   secret4:
     name: bar
+    x-bar: baz
+    x-foo: bar
+x-bar: baz
+x-foo: bar
+x-nested:
+  bar: baz
+  foo: bar

cli/compose/loader/full-struct_test.go

@@ -14,8 +14,16 @@ func fullExampleConfig(workingDir, homeDir string) *types.Config {
 		Services: services(workingDir, homeDir),
 		Networks: networks(),
 		Volumes:  volumes(),
-		Configs:  configs(),
+		Configs:  configs(workingDir),
-		Secrets:  secrets(),
+		Secrets:  secrets(workingDir),
+		Extras: map[string]interface{}{
+			"x-foo": "bar",
+			"x-bar": "baz",
+			"x-nested": map[string]interface{}{
+				"foo": "bar",
+				"bar": "baz",
+			},
+		},
 	}
 }
 
@@ -136,6 +144,10 @@ func services(workingDir, homeDir string) []types.ServiceConfig {
 				"somehost:162.242.195.82",
 				"otherhost:50.31.209.229",
 			},
+			Extras: map[string]interface{}{
+				"x-bar": "baz",
+				"x-foo": "bar",
+			},
 			HealthCheck: &types.HealthCheckConfig{
 				Test:        types.HealthCheckTest([]string{"CMD-SHELL", "echo \"hello world\""}),
 				Interval:    durationPtr(10 * time.Second),
@@ -392,6 +404,10 @@ func networks() map[string]types.NetworkConfig {
 		"other-external-network": {
 			Name:     "my-cool-network",
 			External: types.External{External: true},
+			Extras: map[string]interface{}{
+				"x-bar": "baz",
+				"x-foo": "bar",
+			},
 		},
 	}
 }
@@ -428,14 +444,18 @@ func volumes() map[string]types.VolumeConfig {
 		"external-volume3": {
 			Name:     "this-is-volume3",
 			External: types.External{External: true},
+			Extras: map[string]interface{}{
+				"x-bar": "baz",
+				"x-foo": "bar",
+			},
 		},
 	}
 }
 
-func configs() map[string]types.ConfigObjConfig {
+func configs(workingDir string) map[string]types.ConfigObjConfig {
 	return map[string]types.ConfigObjConfig{
 		"config1": {
-			File: "./config_data",
+			File: filepath.Join(workingDir, "config_data"),
 			Labels: map[string]string{
 				"foo": "bar",
 			},
@@ -445,18 +465,24 @@ func configs() map[string]types.ConfigObjConfig {
 			External: types.External{External: true},
 		},
 		"config3": {
+			Name:     "config3",
 			External: types.External{External: true},
 		},
 		"config4": {
 			Name: "foo",
+			File: workingDir,
+			Extras: map[string]interface{}{
+				"x-bar": "baz",
+				"x-foo": "bar",
+			},
 		},
 	}
 }
 
-func secrets() map[string]types.SecretConfig {
+func secrets(workingDir string) map[string]types.SecretConfig {
 	return map[string]types.SecretConfig{
 		"secret1": {
-			File: "./secret_data",
+			File: filepath.Join(workingDir, "secret_data"),
 			Labels: map[string]string{
 				"foo": "bar",
 			},
@@ -466,10 +492,16 @@ func secrets() map[string]types.SecretConfig {
 			External: types.External{External: true},
 		},
 		"secret3": {
+			Name:     "secret3",
 			External: types.External{External: true},
 		},
 		"secret4": {
 			Name: "bar",
+			File: workingDir,
+			Extras: map[string]interface{}{
+				"x-bar": "baz",
+				"x-foo": "bar",
+			},
 		},
 	}
 }
@@ -760,6 +792,8 @@ services:
       tmpfs:
         size: 10000
     working_dir: /code
+    x-bar: baz
+    x-foo: bar
 networks:
   external-network:
     name: external-network
@@ -767,6 +801,8 @@ networks:
   other-external-network:
     name: my-cool-network
     external: true
+    x-bar: baz
+    x-foo: bar
   other-network:
     driver: overlay
     driver_opts:
@@ -793,6 +829,8 @@ volumes:
   external-volume3:
     name: this-is-volume3
     external: true
+    x-bar: baz
+    x-foo: bar
   other-external-volume:
     name: my-cool-volume
     external: true
@@ -806,27 +844,46 @@ volumes:
   some-volume: {}
 secrets:
   secret1:
-    file: ./secret_data
+    file: %s/secret_data
     labels:
       foo: bar
   secret2:
     name: my_secret
     external: true
   secret3:
+    name: secret3
     external: true
   secret4:
     name: bar
+    file: %s
+    x-bar: baz
+    x-foo: bar
 configs:
   config1:
-    file: ./config_data
+    file: %s/config_data
     labels:
       foo: bar
   config2:
     name: my_config
     external: true
   config3:
+    name: config3
     external: true
   config4:
     name: foo
-`, filepath.Join(workingDir, "static"), filepath.Join(workingDir, "opt"))
+    file: %s
+    x-bar: baz
+    x-foo: bar
+x-bar: baz
+x-foo: bar
+x-nested:
+  bar: baz
+  foo: bar
+`,
+		filepath.Join(workingDir, "static"),
+		filepath.Join(workingDir, "opt"),
+		workingDir,
+		workingDir,
+		workingDir,
+		workingDir)
 }

cli/compose/loader/loader.go

@@ -147,6 +147,7 @@ func loadSections(config map[string]interface{}, configDetails types.ConfigDetai
 			return nil, err
 		}
 	}
+	cfg.Extras = getExtras(config)
 	return &cfg, nil
 }
 
@@ -364,9 +365,32 @@ func LoadService(name string, serviceDict map[string]interface{}, workingDir str
 	if err := resolveVolumePaths(serviceConfig.Volumes, workingDir, lookupEnv); err != nil {
 		return nil, err
 	}
+
+	serviceConfig.Extras = getExtras(serviceDict)
+
 	return serviceConfig, nil
 }
 
+func loadExtras(name string, source map[string]interface{}) map[string]interface{} {
+	if dict, ok := source[name].(map[string]interface{}); ok {
+		return getExtras(dict)
+	}
+	return nil
+}
+
+func getExtras(dict map[string]interface{}) map[string]interface{} {
+	extras := map[string]interface{}{}
+	for key, value := range dict {
+		if strings.HasPrefix(key, "x-") {
+			extras[key] = value
+		}
+	}
+	if len(extras) == 0 {
+		return nil
+	}
+	return extras
+}
+
 func updateEnvironment(environment map[string]*string, vars map[string]*string, lookupEnv template.Mapping) {
 	for k, v := range vars {
 		interpolatedV, ok := lookupEnv(k)
@@ -479,6 +503,7 @@ func LoadNetworks(source map[string]interface{}, version string) (map[string]typ
 		case network.Name == "":
 			network.Name = name
 		}
+		network.Extras = loadExtras(name, source)
 		networks[name] = network
 	}
 	return networks, nil
@@ -521,6 +546,7 @@ func LoadVolumes(source map[string]interface{}, version string) (map[string]type
 		case volume.Name == "":
 			volume.Name = name
 		}
+		volume.Extras = loadExtras(name, source)
 		volumes[name] = volume
 	}
 	return volumes, nil
@@ -538,7 +564,9 @@ func LoadSecrets(source map[string]interface{}, details types.ConfigDetails) (ma
 		if err != nil {
 			return nil, err
 		}
-		secrets[name] = types.SecretConfig(obj)
+		secretConfig := types.SecretConfig(obj)
+		secretConfig.Extras = loadExtras(name, source)
+		secrets[name] = secretConfig
 	}
 	return secrets, nil
 }
@@ -555,7 +583,9 @@ func LoadConfigObjs(source map[string]interface{}, details types.ConfigDetails)
 		if err != nil {
 			return nil, err
 		}
-		configs[name] = types.ConfigObjConfig(obj)
+		configConfig := types.ConfigObjConfig(obj)
+		configConfig.Extras = loadExtras(name, source)
+		configs[name] = configConfig
 	}
 	return configs, nil
 }

cli/compose/loader/loader_test.go

@@ -182,6 +182,23 @@ func TestLoad(t *testing.T) {
 	assert.Check(t, is.DeepEqual(sampleConfig.Volumes, actual.Volumes))
 }
 
+func TestLoadExtras(t *testing.T) {
+	actual, err := loadYAML(`
+version: "3.7"
+services:
+  foo:
+    image: busybox
+    x-foo: bar`)
+	assert.NilError(t, err)
+	assert.Check(t, is.Len(actual.Services, 1))
+	service := actual.Services[0]
+	assert.Check(t, is.Equal("busybox", service.Image))
+	extras := map[string]interface{}{
+		"x-foo": "bar",
+	}
+	assert.Check(t, is.DeepEqual(extras, service.Extras))
+}
+
 func TestLoadV31(t *testing.T) {
 	actual, err := loadYAML(`
 version: "3.1"
@@ -825,6 +842,9 @@ func TestFullExample(t *testing.T) {
 	assert.Check(t, is.DeepEqual(expectedConfig.Services, config.Services))
 	assert.Check(t, is.DeepEqual(expectedConfig.Networks, config.Networks))
 	assert.Check(t, is.DeepEqual(expectedConfig.Volumes, config.Volumes))
+	assert.Check(t, is.DeepEqual(expectedConfig.Secrets, config.Secrets))
+	assert.Check(t, is.DeepEqual(expectedConfig.Configs, config.Configs))
+	assert.Check(t, is.DeepEqual(expectedConfig.Extras, config.Extras))
 }
 
 func TestLoadTmpfsVolume(t *testing.T) {

cli/compose/types/types.go

@@ -77,6 +77,7 @@ type Config struct {
 	Volumes  map[string]VolumeConfig
 	Secrets  map[string]SecretConfig
 	Configs  map[string]ConfigObjConfig
+	Extras   map[string]interface{} `yaml:",inline"`
 }
 
 // Services is a list of ServiceConfig
@@ -142,6 +143,7 @@ type ServiceConfig struct {
 	Volumes         []ServiceVolumeConfig            `yaml:",omitempty"`
 	WorkingDir      string                           `mapstructure:"working_dir" yaml:"working_dir,omitempty"`
 	Isolation       string                           `mapstructure:"isolation" yaml:"isolation,omitempty"`
+	Extras          map[string]interface{}           `yaml:",inline"`
 }
 
 // BuildConfig is a type for build
@@ -362,6 +364,7 @@ type NetworkConfig struct {
 	Internal   bool                   `yaml:",omitempty"`
 	Attachable bool                   `yaml:",omitempty"`
 	Labels     Labels                 `yaml:",omitempty"`
+	Extras     map[string]interface{} `yaml:",inline"`
 }
 
 // IPAMConfig for a network
@@ -382,6 +385,7 @@ type VolumeConfig struct {
 	DriverOpts map[string]string      `mapstructure:"driver_opts" yaml:"driver_opts,omitempty"`
 	External   External               `yaml:",omitempty"`
 	Labels     Labels                 `yaml:",omitempty"`
+	Extras     map[string]interface{} `yaml:",inline"`
 }
 
 // External identifies a Volume or Network as a reference to a resource that is
@@ -412,6 +416,7 @@ type FileObjectConfig struct {
 	File     string                 `yaml:",omitempty"`
 	External External               `yaml:",omitempty"`
 	Labels   Labels                 `yaml:",omitempty"`
+	Extras   map[string]interface{} `yaml:",inline"`
 }
 
 // SecretConfig for a secret