config: Introduce DeprecatedConfig

This struct allows us to move all the deprecated config options off of
the main config struct, and keeps all the deprecation logic in a single
place, instead of spread across 3+ places.

agent/config/builder.go

@@ -346,10 +346,12 @@ func (b *builder) build() (rt RuntimeConfig, err error) {
 		for _, err := range validateEnterpriseConfigKeys(&c2) {
 			b.warn("%s", err)
 		}
+		b.Warnings = append(b.Warnings, md.Warnings...)
 
 		// if we have a single 'check' or 'service' we need to add them to the
 		// list of checks and services first since we cannot merge them
 		// generically and later values would clobber earlier ones.
+		// TODO: move to applyDeprecatedConfig
 		if c2.Check != nil {
 			c2.Checks = append(c2.Checks, *c2.Check)
 			c2.Check = nil
@@ -733,16 +735,6 @@ func (b *builder) build() (rt RuntimeConfig, err error) {
 
 	aclsEnabled := false
 	primaryDatacenter := strings.ToLower(stringVal(c.PrimaryDatacenter))
-	if c.ACLDatacenter != nil {
-		b.warn("The 'acl_datacenter' field is deprecated. Use the 'primary_datacenter' field instead.")
-
-		if primaryDatacenter == "" {
-			primaryDatacenter = strings.ToLower(stringVal(c.ACLDatacenter))
-		}
-
-		// when the acl_datacenter config is used it implicitly enables acls
-		aclsEnabled = true
-	}
 
 	if c.ACL.Enabled != nil {
 		aclsEnabled = boolVal(c.ACL.Enabled)
@@ -887,7 +879,7 @@ func (b *builder) build() (rt RuntimeConfig, err error) {
 			EnablePersistence:   boolValWithDefault(c.ACL.EnableTokenPersistence, false),
 			ACLDefaultToken:     stringValWithDefault(c.ACL.Tokens.Default, stringVal(c.ACLToken)),
 			ACLAgentToken:       stringValWithDefault(c.ACL.Tokens.Agent, stringVal(c.ACLAgentToken)),
-			ACLAgentMasterToken: stringValWithDefault(c.ACL.Tokens.AgentMaster, stringVal(c.ACLAgentMasterToken)),
+			ACLAgentMasterToken: stringVal(c.ACL.Tokens.AgentMaster),
 			ACLReplicationToken: stringValWithDefault(c.ACL.Tokens.Replication, stringVal(c.ACLReplicationToken)),
 		},
 

agent/config/config.go

@@ -15,7 +15,7 @@ type Source interface {
 	// Source returns an identifier for the Source that can be used in error message
 	Source() string
 	// Parse a configuration and return the result.
-	Parse() (Config, mapstructure.Metadata, error)
+	Parse() (Config, Metadata, error)
 }
 
 // ErrNoData indicates to Builder.Build that the source contained no data, and
@@ -34,9 +34,10 @@ func (f FileSource) Source() string {
 }
 
 // Parse a config file in either JSON or HCL format.
-func (f FileSource) Parse() (Config, mapstructure.Metadata, error) {
+func (f FileSource) Parse() (Config, Metadata, error) {
+	m := Metadata{}
 	if f.Name == "" || f.Data == "" {
-		return Config{}, mapstructure.Metadata{}, ErrNoData
+		return Config{}, m, ErrNoData
 	}
 
 	var raw map[string]interface{}
@@ -51,10 +52,10 @@ func (f FileSource) Parse() (Config, mapstructure.Metadata, error) {
 		err = fmt.Errorf("invalid format: %s", f.Format)
 	}
 	if err != nil {
-		return Config{}, md, err
+		return Config{}, m, err
 	}
 
-	var c Config
+	var target decodeTarget
 	d, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
 		DecodeHook: mapstructure.ComposeDecodeHookFunc(
 			// decode.HookWeakDecodeFromSlice is only necessary when reading from
@@ -66,16 +67,30 @@ func (f FileSource) Parse() (Config, mapstructure.Metadata, error) {
 			decode.HookTranslateKeys,
 		),
 		Metadata: &md,
-		Result:   &c,
+		Result:   &target,
 	})
 	if err != nil {
-		return Config{}, md, err
+		return Config{}, m, err
 	}
 	if err := d.Decode(raw); err != nil {
-		return Config{}, md, err
+		return Config{}, m, err
 	}
 
-	return c, md, nil
+	c, warns := applyDeprecatedConfig(&target)
+	m.Unused = md.Unused
+	m.Keys = md.Keys
+	m.Warnings = warns
+	return c, m, nil
+}
+
+// Metadata created by Source.Parse
+type Metadata struct {
+	// Keys used in the config file.
+	Keys []string
+	// Unused keys that did not match any struct fields.
+	Unused []string
+	// Warnings caused by deprecated fields
+	Warnings []string
 }
 
 // LiteralSource implements Source and returns an existing Config struct.
@@ -88,8 +103,13 @@ func (l LiteralSource) Source() string {
 	return l.Name
 }
 
-func (l LiteralSource) Parse() (Config, mapstructure.Metadata, error) {
-	return l.Config, mapstructure.Metadata{}, nil
+func (l LiteralSource) Parse() (Config, Metadata, error) {
+	return l.Config, Metadata{}, nil
+}
+
+type decodeTarget struct {
+	DeprecatedConfig `mapstructure:",squash"`
+	Config           `mapstructure:",squash"`
 }
 
 // Cache configuration for the agent/cache.
@@ -110,12 +130,8 @@ type Cache struct {
 // configuration it should be treated as an external API which cannot be
 // changed and refactored at will since this will break existing setups.
 type Config struct {
-	// DEPRECATED (ACL-Legacy-Compat) - moved into the "acl.tokens" stanza
-	ACLAgentMasterToken *string `mapstructure:"acl_agent_master_token"`
 	// DEPRECATED (ACL-Legacy-Compat) - moved into the "acl.tokens" stanza
 	ACLAgentToken *string `mapstructure:"acl_agent_token"`
-	// DEPRECATED (ACL-Legacy-Compat) - moved to "primary_datacenter"
-	ACLDatacenter *string `mapstructure:"acl_datacenter"`
 	// DEPRECATED (ACL-Legacy-Compat) - moved into the "acl" stanza
 	ACLDefaultPolicy *string `mapstructure:"acl_default_policy"`
 	// DEPRECATED (ACL-Legacy-Compat) - moved into the "acl" stanza

agent/config/deprecated.go

@@ -0,0 +1,42 @@
+package config
+
+import "fmt"
+
+type DeprecatedConfig struct {
+	// DEPRECATED (ACL-Legacy-Compat) - moved into the "acl.tokens" stanza
+	ACLAgentMasterToken *string `mapstructure:"acl_agent_master_token"`
+	// DEPRECATED (ACL-Legacy-Compat) - moved to "primary_datacenter"
+	ACLDatacenter *string `mapstructure:"acl_datacenter"`
+}
+
+func applyDeprecatedConfig(d *decodeTarget) (Config, []string) {
+	dep := d.DeprecatedConfig
+	var warns []string
+
+	if dep.ACLAgentMasterToken != nil {
+		if d.Config.ACL.Tokens.AgentMaster == nil {
+			d.Config.ACL.Tokens.AgentMaster = dep.ACLAgentMasterToken
+		}
+		warns = append(warns, deprecationWarning("acl_agent_master_token", "acl.tokens.agent_master"))
+	}
+
+	if dep.ACLDatacenter != nil {
+		if d.Config.PrimaryDatacenter == nil {
+			d.Config.PrimaryDatacenter = dep.ACLDatacenter
+		}
+
+		// when the acl_datacenter config is used it implicitly enables acls
+		d.Config.ACL.Enabled = pBool(true)
+		warns = append(warns, deprecationWarning("acl_datacenter", "primary_datacenter"))
+	}
+
+	return d.Config, warns
+}
+
+func deprecationWarning(old, new string) string {
+	return fmt.Sprintf("The '%v' field is deprecated. Use the '%v' field instead.", old, new)
+}
+
+func pBool(v bool) *bool {
+	return &v
+}

agent/config/merge_test.go

@@ -52,7 +52,6 @@ func TestMerge(t *testing.T) {
 	}
 }
 
-func pBool(v bool) *bool                { return &v }
 func pInt(v int) *int                   { return &v }
 func pString(v string) *string          { return &v }
 func pDuration(v time.Duration) *string { s := v.String(); return &s }

agent/config/runtime_test.go

@@ -5903,6 +5903,7 @@ func TestLoad_FullConfig(t *testing.T) {
 
 	expectedWarns := []string{
 		`The 'acl_datacenter' field is deprecated. Use the 'primary_datacenter' field instead.`,
+		`The 'acl_agent_master_token' field is deprecated. Use the 'acl.tokens.agent_master' field instead.`,
 		`bootstrap_expect > 0: expecting 53 servers`,
 	}
 	expectedWarns = append(expectedWarns, enterpriseConfigKeyWarnings...)