Add Yaml validation

Fix #1292

Transform the Yaml struct to JSON and validate it against a JSON schema.

Signed-off-by: Thomas Gazagnaire <thomas@gazagnaire.org>

src/cmd/moby/config.go

@@ -15,6 +15,7 @@ import (
 	log "github.com/Sirupsen/logrus"
 	"github.com/docker/engine-api/types"
 	"github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/xeipuuv/gojsonschema"
 	"gopkg.in/yaml.v2"
 )
 
@@ -80,11 +81,56 @@ type MobyImage struct {
 	Sysctl            map[string]string
 }
 
+// recursively convert the map keys from `interface{}` to `string`
+// this is needed to convert "yaml" interfaces to "JSON" interfaces
+// see http://stackoverflow.com/questions/40737122/convert-yaml-to-json-without-struct-golang#answer-40737676
+func convert(i interface{}) interface{} {
+	switch x := i.(type) {
+	case map[interface{}]interface{}:
+		m2 := map[string]interface{}{}
+		for k, v := range x {
+			m2[k.(string)] = convert(v)
+		}
+		return m2
+	case []interface{}:
+		for i, v := range x {
+			x[i] = convert(v)
+		}
+	}
+	return i
+}
+
 // NewConfig parses a config file
 func NewConfig(config []byte) (*Moby, error) {
 	m := Moby{}
 
-	err := yaml.Unmarshal(config, &m)
+	// Parse raw yaml
+	var rawYaml interface{}
+	err := yaml.Unmarshal(config, &rawYaml)
+	if err != nil {
+		return &m, err
+	}
+
+	// Convert to raw JSON
+	rawJSON := convert(rawYaml)
+
+	// Validate raw yaml with JSON schema
+	schemaLoader := gojsonschema.NewStringLoader(schema)
+	documentLoader := gojsonschema.NewGoLoader(rawJSON)
+	result, err := gojsonschema.Validate(schemaLoader, documentLoader)
+	if err != nil {
+		return &m, err
+	}
+	if !result.Valid() {
+		fmt.Printf("The configuration file is invalid:\n")
+		for _, desc := range result.Errors() {
+			fmt.Printf("- %s\n", desc)
+		}
+		return &m, fmt.Errorf("invalid configuration file")
+	}
+
+	// Parse yaml
+	err = yaml.Unmarshal(config, &m)
 	if err != nil {
 		return &m, err
 	}

src/cmd/moby/schema.go

@@ -0,0 +1,113 @@
+package main
+
+var schema = string(`
+{
+  "$schema": "http://json-schema.org/draft-04/schema#",
+  "title": "Moby Config",
+  "additionalProperties": false,
+  "definitions": {
+    "kernel": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "image": { "type": "string"},
+        "cmdline": { "type": "string"}
+      }
+    },
+    "file": {
+      "type": "object",
+      "additionalProperties": false,
+        "properties": {
+          "path": {"type": "string"},
+          "directory": {"type": "boolean"},
+          "contents": {"type": "string"}
+        }
+    },
+    "files": {
+        "type": "array", 
+        "items": { "$ref": "#/definitions/file" }
+    },
+    "output": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "format": {"type": "string"},
+        "project": {"type": "string"},
+        "bucket": {"type": "string"},
+        "family": {"type": "string"},
+        "keys": {"type": "string"},
+        "public": {"type": "boolean"},
+        "replace": {"type": "boolean"}
+      }
+    },
+    "outputs": {
+        "type": "array", 
+        "items": { "$ref": "#/definitions/output" }
+    },
+    "trust": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "image": { "$ref": "#/definitions/strings" },
+        "org": { "$ref": "#/definitions/strings" }
+      }
+    },
+    "strings": {
+        "type": "array", 
+        "items": {"type": "string"}
+    },
+    "image": {
+      "type": "object",
+      "additionalProperties": false,
+      "required": ["name", "image"],
+      "properties": {
+        "name": {"type": "string"},
+        "image": {"type": "string"},
+        "capabilities": { "$ref": "#/definitions/strings" },
+        "mounts": { "$ref": "#/definitions/strings" },
+        "binds": { "$ref": "#/definitions/strings" },
+        "tmpfs": { "$ref": "#/definitions/strings" },
+        "command": { "$ref": "#/definitions/strings" },
+        "env": { "$ref": "#/definitions/strings" },
+        "cwd": { "type": "string"},
+        "net": { "type": "string"},
+        "pid": { "type": "string"},
+        "ipc": { "type": "string"},
+        "uts": { "type": "string"},
+        "readonly": { "type": "boolean"},
+        "maskedPaths": { "$ref": "#/definitions/strings" },
+        "readonlyPaths": { "$ref": "#/definitions/strings" },
+        "uid": {"type": "integer"},
+        "gid": {"type": "integer"},
+        "additionalGids": {
+            "type": "array", 
+            "items": { "type": "integer" }
+        },
+        "noNewPrivileges": {"type": "boolean"},
+        "hostname": {"type": "string"},
+        "oomScoreAdj": {"type": "integer"},
+        "disableOOMKiller": {"type": "boolean"},
+        "rootfsPropagation": {"type": "string"},
+        "cgroupsPath": {"type": "string"},
+        "sysctl": {
+            "type": "array", 
+            "items": { "$ref": "#/definitions/strings" }
+        }
+      }
+    },
+    "images": {
+        "type": "array", 
+        "items": { "$ref": "#/definitions/image" }
+    }
+  },
+  "properties": {
+    "kernel": { "$ref": "#/definitions/kernel" },  
+    "init": { "$ref": "#/definitions/strings" },
+    "onboot": { "$ref": "#/definitions/images" },
+    "services": { "$ref": "#/definitions/images" },
+    "trust": { "$ref": "#/definitions/trust" },
+    "files": { "$ref": "#/definitions/files" },
+    "outputs": { "$ref": "#/definitions/outputs" }
+  }
+}
+`)