Check allowed values for fields (#771)

Fields can include a list of allowed values. Check that the values of
these fields are between the allowed ones.

Author: jsoriano

internal/fields/model.go

@@ -9,22 +9,25 @@ import (
 	"strings"
 
 	"gopkg.in/yaml.v3"
+
+	"github.com/elastic/elastic-package/internal/common"
 )
 
 // FieldDefinition describes a single field with its properties.
 type FieldDefinition struct {
-	Name        string            `yaml:"name"`
-	Description string            `yaml:"description"`
-	Type        string            `yaml:"type"`
-	Value       string            `yaml:"value"` // The value to associate with a constant_keyword field.
-	Pattern     string            `yaml:"pattern"`
-	Unit        string            `yaml:"unit"`
-	MetricType  string            `yaml:"metric_type"`
-	External    string            `yaml:"external"`
-	Index       *bool             `yaml:"index"`
-	DocValues   *bool             `yaml:"doc_values"`
-	Fields      FieldDefinitions  `yaml:"fields,omitempty"`
-	MultiFields []FieldDefinition `yaml:"multi_fields,omitempty"`
+	Name          string            `yaml:"name"`
+	Description   string            `yaml:"description"`
+	Type          string            `yaml:"type"`
+	Value         string            `yaml:"value"` // The value to associate with a constant_keyword field.
+	AllowedValues AllowedValues     `yaml:"allowed_values"`
+	Pattern       string            `yaml:"pattern"`
+	Unit          string            `yaml:"unit"`
+	MetricType    string            `yaml:"metric_type"`
+	External      string            `yaml:"external"`
+	Index         *bool             `yaml:"index"`
+	DocValues     *bool             `yaml:"doc_values"`
+	Fields        FieldDefinitions  `yaml:"fields,omitempty"`
+	MultiFields   []FieldDefinition `yaml:"multi_fields,omitempty"`
 }
 
 func (orig *FieldDefinition) Update(fd FieldDefinition) {
@@ -40,6 +43,9 @@ func (orig *FieldDefinition) Update(fd FieldDefinition) {
 	if fd.Value != "" {
 		orig.Value = fd.Value
 	}
+	if len(fd.AllowedValues) > 0 {
+		orig.AllowedValues = fd.AllowedValues
+	}
 	if fd.Pattern != "" {
 		orig.Pattern = fd.Pattern
 	}
@@ -182,3 +188,31 @@ func cleanNested(parent *FieldDefinition) (base []FieldDefinition) {
 	parent.Fields = nested
 	return base
 }
+
+// AllowedValues is the list of allowed values for a field.
+type AllowedValues []AllowedValue
+
+// Allowed returns true if a given value is allowed.
+func (avs AllowedValues) IsAllowed(value string) bool {
+	if len(avs) == 0 {
+		// No configured allowed values, any value is allowed.
+		return true
+	}
+	return common.StringSliceContains(avs.Values(), value)
+}
+
+// Values returns the list of allowed values.
+func (avs AllowedValues) Values() []string {
+	var values []string
+	for _, v := range avs {
+		values = append(values, v.Name)
+	}
+	return values
+}
+
+// AllowedValue is one of the allowed values for a field.
+type AllowedValue struct {
+	Name               string   `yaml:"name"`
+	Description        string   `yaml:"description"`
+	ExpectedEventTypes []string `yaml:"expected_event_types"`
+}

internal/fields/validate.go

@@ -391,6 +391,9 @@ func (v *Validator) parseSingleElementValue(key string, definition FieldDefiniti
 		if err := ensurePatternMatches(key, valStr, definition.Pattern); err != nil {
 			return err
 		}
+		if err := ensureAllowedValues(key, valStr, definition.AllowedValues); err != nil {
+			return err
+		}
 	// Normal text fields should be of type string.
 	// If a pattern is provided, it checks if the value matches.
 	case "keyword", "text":
@@ -402,6 +405,9 @@ func (v *Validator) parseSingleElementValue(key string, definition FieldDefiniti
 		if err := ensurePatternMatches(key, valStr, definition.Pattern); err != nil {
 			return err
 		}
+		if err := ensureAllowedValues(key, valStr, definition.AllowedValues); err != nil {
+			return err
+		}
 	// Dates are expected to be formatted as strings or as seconds or milliseconds
 	// since epoch.
 	// If it is a string and a pattern is provided, it checks if the value matches.
@@ -531,3 +537,12 @@ func ensureConstantKeywordValueMatches(key, value, constantKeywordValue string)
 	}
 	return nil
 }
+
+// ensureAllowedValues validates that the document's field value
+// is one of the allowed values.
+func ensureAllowedValues(key, value string, allowedValues AllowedValues) error {
+	if !allowedValues.IsAllowed(value) {
+		return fmt.Errorf("field %q's value %q is not one of the allowed values (%s)", key, value, strings.Join(allowedValues.Values(), ", "))
+	}
+	return nil
+}

internal/fields/validate_test.go

@@ -300,6 +300,54 @@ func Test_parseElementValue(t *testing.T) {
 			},
 			fail: true,
 		},
+		// allowed values
+		{
+			key:   "allowed values",
+			value: "configuration",
+			definition: FieldDefinition{
+				Type: "keyword",
+				AllowedValues: AllowedValues{
+					{
+						Name: "configuration",
+					},
+					{
+						Name: "network",
+					},
+				},
+			},
+		},
+		{
+			key:   "not allowed value",
+			value: "display",
+			definition: FieldDefinition{
+				Type: "keyword",
+				AllowedValues: AllowedValues{
+					{
+						Name: "configuration",
+					},
+					{
+						Name: "network",
+					},
+				},
+			},
+			fail: true,
+		},
+		{
+			key:   "not allowed value in array",
+			value: []string{"configuration", "display"},
+			definition: FieldDefinition{
+				Type: "keyword",
+				AllowedValues: AllowedValues{
+					{
+						Name: "configuration",
+					},
+					{
+						Name: "network",
+					},
+				},
+			},
+			fail: true,
+		},
 		// fields shouldn't be stored in groups
 		{
 			key:   "host",