refactor(config)!: extract config interfaces to pkg/api/config (#566)

Decouples the pkg/kubernetes module from pkg/config by introducing
interfaces for configuration access. This allows pkg/kubernetes to
depend on abstractions rather than the concrete StaticConfig type.

Changes:
- Add AuthProvider, ClusterProvider, DeniedResourcesProvider, and
  ExtendedProvider interfaces in pkg/api/config
- Move cluster provider strategy constants to pkg/api/config
- Move GroupVersionKind struct to pkg/api/config
- Update pkg/kubernetes to use the new interfaces
- StaticConfig now implements the Config interface

Signed-off-by: Marc Nuri <[email protected]>

Author: manusa

pkg/api/config/config.go

@@ -0,0 +1,53 @@
+package config
+
+const (
+	ClusterProviderKubeConfig = "kubeconfig"
+	ClusterProviderInCluster  = "in-cluster"
+	ClusterProviderDisabled   = "disabled"
+)
+
+type AuthProvider interface {
+	// IsRequireOAuth indicates whether OAuth authentication is required.
+	IsRequireOAuth() bool
+}
+
+type ClusterProvider interface {
+	// GetClusterProviderStrategy returns the cluster provider strategy (if configured).
+	GetClusterProviderStrategy() string
+	// GetKubeConfigPath returns the path to the kubeconfig file (if configured).
+	GetKubeConfigPath() string
+}
+
+// Extended is the interface that all configuration extensions must implement.
+// Each extended config manager registers a factory function to parse its config from TOML primitives
+type Extended interface {
+	// Validate validates the extended configuration.  Returns an error if the configuration is invalid.
+	Validate() error
+}
+
+type ExtendedProvider interface {
+	// GetProviderConfig returns the extended configuration for the given provider strategy.
+	// The boolean return value indicates whether the configuration was found.
+	GetProviderConfig(strategy string) (Extended, bool)
+	// GetToolsetConfig returns the extended configuration for the given toolset name.
+	// The boolean return value indicates whether the configuration was found.
+	GetToolsetConfig(name string) (Extended, bool)
+}
+
+type GroupVersionKind struct {
+	Group   string `json:"group" toml:"group"`
+	Version string `json:"version" toml:"version"`
+	Kind    string `json:"kind,omitempty" toml:"kind,omitempty"`
+}
+
+type DeniedResourcesProvider interface {
+	// GetDeniedResources returns a list of GroupVersionKinds that are denied.
+	GetDeniedResources() []GroupVersionKind
+}
+
+type BaseConfig interface {
+	AuthProvider
+	ClusterProvider
+	DeniedResourcesProvider
+	ExtendedProvider
+}

pkg/config/config.go

@@ -10,23 +10,18 @@ import (
 	"strings"
 
 	"github.com/BurntSushi/toml"
+	configapi "github.com/containers/kubernetes-mcp-server/pkg/api/config"
 	"k8s.io/klog/v2"
 )
 
 const (
 	DefaultDropInConfigDir = "conf.d"
 )
 
-const (
-	ClusterProviderKubeConfig = "kubeconfig"
-	ClusterProviderInCluster  = "in-cluster"
-	ClusterProviderDisabled   = "disabled"
-)
-
 // StaticConfig is the configuration for the server.
 // It allows to configure server specific settings and tools to be enabled or disabled.
 type StaticConfig struct {
-	DeniedResources []GroupVersionKind `toml:"denied_resources"`
+	DeniedResources []configapi.GroupVersionKind `toml:"denied_resources"`
 
 	LogLevel   int    `toml:"log_level,omitzero"`
 	Port       string `toml:"port,omitempty"`
@@ -80,19 +75,15 @@ type StaticConfig struct {
 	ToolsetConfigs map[string]toml.Primitive `toml:"toolset_configs,omitempty"`
 
 	// Internal: parsed provider configs (not exposed to TOML package)
-	parsedClusterProviderConfigs map[string]Extended
+	parsedClusterProviderConfigs map[string]configapi.Extended
 	// Internal: parsed toolset configs (not exposed to TOML package)
-	parsedToolsetConfigs map[string]Extended
+	parsedToolsetConfigs map[string]configapi.Extended
 
 	// Internal: the config.toml directory, to help resolve relative file paths
 	configDirPath string
 }
 
-type GroupVersionKind struct {
-	Group   string `toml:"group"`
-	Version string `toml:"version"`
-	Kind    string `toml:"kind,omitempty"`
-}
+var _ configapi.BaseConfig = (*StaticConfig)(nil)
 
 type ReadConfigOpt func(cfg *StaticConfig)
 
@@ -292,13 +283,29 @@ func ReadToml(configData []byte, opts ...ReadConfigOpt) (*StaticConfig, error) {
 	return config, nil
 }
 
-func (c *StaticConfig) GetProviderConfig(strategy string) (Extended, bool) {
-	config, ok := c.parsedClusterProviderConfigs[strategy]
+func (c *StaticConfig) GetClusterProviderStrategy() string {
+	return c.ClusterProviderStrategy
+}
+
+func (c *StaticConfig) GetDeniedResources() []configapi.GroupVersionKind {
+	return c.DeniedResources
+}
 
-	return config, ok
+func (c *StaticConfig) GetKubeConfigPath() string {
+	return c.KubeConfig
 }
 
-func (c *StaticConfig) GetToolsetConfig(name string) (Extended, bool) {
+func (c *StaticConfig) GetProviderConfig(strategy string) (configapi.Extended, bool) {
+	cfg, ok := c.parsedClusterProviderConfigs[strategy]
+
+	return cfg, ok
+}
+
+func (c *StaticConfig) GetToolsetConfig(name string) (configapi.Extended, bool) {
 	cfg, ok := c.parsedToolsetConfigs[name]
 	return cfg, ok
 }
+
+func (c *StaticConfig) IsRequireOAuth() bool {
+	return c.RequireOAuth
+}

pkg/config/config_test.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"testing"
 
+	configapi "github.com/containers/kubernetes-mcp-server/pkg/api/config"
 	"github.com/stretchr/testify/suite"
 )
 
@@ -136,11 +137,11 @@ func (s *ConfigSuite) TestReadConfigValid() {
 	s.Run("denied_resources", func() {
 		s.Require().Lenf(config.DeniedResources, 2, "Expected 2 denied resources, got %d", len(config.DeniedResources))
 		s.Run("contains apps/v1/Deployment", func() {
-			s.Contains(config.DeniedResources, GroupVersionKind{Group: "apps", Version: "v1", Kind: "Deployment"},
+			s.Contains(config.DeniedResources, configapi.GroupVersionKind{Group: "apps", Version: "v1", Kind: "Deployment"},
 				"Expected denied resources to contain apps/v1/Deployment")
 		})
 		s.Run("contains rbac.authorization.k8s.io/v1/Role", func() {
-			s.Contains(config.DeniedResources, GroupVersionKind{Group: "rbac.authorization.k8s.io", Version: "v1", Kind: "Role"},
+			s.Contains(config.DeniedResources, configapi.GroupVersionKind{Group: "rbac.authorization.k8s.io", Version: "v1", Kind: "Role"},
 				"Expected denied resources to contain rbac.authorization.k8s.io/v1/Role")
 		})
 	})
@@ -777,16 +778,16 @@ func (s *ConfigSuite) TestDropInWithDeniedResources() {
 
 	s.Run("drop-in replaces denied_resources array", func() {
 		s.Len(config.DeniedResources, 2, "denied_resources should have 2 entries from drop-in")
-		s.Contains(config.DeniedResources, GroupVersionKind{
+		s.Contains(config.DeniedResources, configapi.GroupVersionKind{
 			Group: "rbac.authorization.k8s.io", Version: "v1", Kind: "ClusterRole",
 		})
-		s.Contains(config.DeniedResources, GroupVersionKind{
+		s.Contains(config.DeniedResources, configapi.GroupVersionKind{
 			Group: "rbac.authorization.k8s.io", Version: "v1", Kind: "ClusterRoleBinding",
 		})
 	})
 
 	s.Run("original denied_resources from main config are replaced", func() {
-		s.NotContains(config.DeniedResources, GroupVersionKind{
+		s.NotContains(config.DeniedResources, configapi.GroupVersionKind{
 			Group: "apps", Version: "v1", Kind: "Deployment",
 		}, "original entry should be replaced by drop-in")
 	})

pkg/config/extended.go

@@ -5,15 +5,10 @@ import (
 	"fmt"
 
 	"github.com/BurntSushi/toml"
+	configapi "github.com/containers/kubernetes-mcp-server/pkg/api/config"
 )
 
-// Extended is the interface that all configuration extensions must implement.
-// Each extended config manager registers a factory function to parse its config from TOML primitives
-type Extended interface {
-	Validate() error
-}
-
-type ExtendedConfigParser func(ctx context.Context, primitive toml.Primitive, md toml.MetaData) (Extended, error)
+type ExtendedConfigParser func(ctx context.Context, primitive toml.Primitive, md toml.MetaData) (configapi.Extended, error)
 
 type extendedConfigRegistry struct {
 	parsers map[string]ExtendedConfigParser
@@ -33,11 +28,11 @@ func (r *extendedConfigRegistry) register(name string, parser ExtendedConfigPars
 	r.parsers[name] = parser
 }
 
-func (r *extendedConfigRegistry) parse(ctx context.Context, metaData toml.MetaData, configs map[string]toml.Primitive) (map[string]Extended, error) {
+func (r *extendedConfigRegistry) parse(ctx context.Context, metaData toml.MetaData, configs map[string]toml.Primitive) (map[string]configapi.Extended, error) {
 	if len(configs) == 0 {
-		return make(map[string]Extended), nil
+		return make(map[string]configapi.Extended), nil
 	}
-	parsedConfigs := make(map[string]Extended, len(configs))
+	parsedConfigs := make(map[string]configapi.Extended, len(configs))
 
 	for name, primitive := range configs {
 		parser, ok := r.parsers[name]

pkg/config/provider_config_test.go

@@ -8,6 +8,7 @@ import (
 	"testing"
 
 	"github.com/BurntSushi/toml"
+	configapi "github.com/containers/kubernetes-mcp-server/pkg/api/config"
 	"github.com/stretchr/testify/suite"
 )
 
@@ -31,7 +32,7 @@ type ProviderConfigForTest struct {
 	IntProp  int    `toml:"int_prop"`
 }
 
-var _ Extended = (*ProviderConfigForTest)(nil)
+var _ configapi.Extended = (*ProviderConfigForTest)(nil)
 
 func (p *ProviderConfigForTest) Validate() error {
 	if p.StrProp == "force-error" {
@@ -40,7 +41,7 @@ func (p *ProviderConfigForTest) Validate() error {
 	return nil
 }
 
-func providerConfigForTestParser(_ context.Context, primitive toml.Primitive, md toml.MetaData) (Extended, error) {
+func providerConfigForTestParser(_ context.Context, primitive toml.Primitive, md toml.MetaData) (configapi.Extended, error) {
 	var providerConfigForTest ProviderConfigForTest
 	if err := md.PrimitiveDecode(primitive, &providerConfigForTest); err != nil {
 		return nil, err
@@ -129,7 +130,7 @@ func (s *ProviderConfigSuite) TestReadConfigUnregisteredProviderConfig() {
 }
 
 func (s *ProviderConfigSuite) TestReadConfigParserError() {
-	RegisterProviderConfig("test", func(ctx context.Context, primitive toml.Primitive, md toml.MetaData) (Extended, error) {
+	RegisterProviderConfig("test", func(ctx context.Context, primitive toml.Primitive, md toml.MetaData) (configapi.Extended, error) {
 		return nil, errors.New("parser error forced by test")
 	})
 	invalidConfigPath := s.writeConfig(`
@@ -152,7 +153,7 @@ func (s *ProviderConfigSuite) TestReadConfigParserError() {
 
 func (s *ProviderConfigSuite) TestConfigDirPathInContext() {
 	var capturedDirPath string
-	RegisterProviderConfig("test", func(ctx context.Context, primitive toml.Primitive, md toml.MetaData) (Extended, error) {
+	RegisterProviderConfig("test", func(ctx context.Context, primitive toml.Primitive, md toml.MetaData) (configapi.Extended, error) {
 		capturedDirPath = ConfigDirPathFromContext(ctx)
 		var providerConfigForTest ProviderConfigForTest
 		if err := md.PrimitiveDecode(primitive, &providerConfigForTest); err != nil {
@@ -328,7 +329,7 @@ func (s *ProviderConfigSuite) TestStandaloneConfigDirWithExtendedConfig() {
 func (s *ProviderConfigSuite) TestConfigDirPathInContextStandalone() {
 	// Test that configDirPath is correctly set in context for standalone --config-dir
 	var capturedDirPath string
-	RegisterProviderConfig("test", func(ctx context.Context, primitive toml.Primitive, md toml.MetaData) (Extended, error) {
+	RegisterProviderConfig("test", func(ctx context.Context, primitive toml.Primitive, md toml.MetaData) (configapi.Extended, error) {
 		capturedDirPath = ConfigDirPathFromContext(ctx)
 		var providerConfigForTest ProviderConfigForTest
 		if err := md.PrimitiveDecode(primitive, &providerConfigForTest); err != nil {

pkg/config/toolset_config_test.go

@@ -8,6 +8,7 @@ import (
 	"testing"
 
 	"github.com/BurntSushi/toml"
+	configapi "github.com/containers/kubernetes-mcp-server/pkg/api/config"
 	"github.com/stretchr/testify/suite"
 )
 
@@ -31,7 +32,7 @@ type ToolsetConfigForTest struct {
 	Timeout  int    `toml:"timeout"`
 }
 
-var _ Extended = (*ToolsetConfigForTest)(nil)
+var _ configapi.Extended = (*ToolsetConfigForTest)(nil)
 
 func (t *ToolsetConfigForTest) Validate() error {
 	if t.Endpoint == "force-error" {
@@ -40,7 +41,7 @@ func (t *ToolsetConfigForTest) Validate() error {
 	return nil
 }
 
-func toolsetConfigForTestParser(_ context.Context, primitive toml.Primitive, md toml.MetaData) (Extended, error) {
+func toolsetConfigForTestParser(_ context.Context, primitive toml.Primitive, md toml.MetaData) (configapi.Extended, error) {
 	var toolsetConfigForTest ToolsetConfigForTest
 	if err := md.PrimitiveDecode(primitive, &toolsetConfigForTest); err != nil {
 		return nil, err
@@ -127,7 +128,7 @@ func (s *ToolsetConfigSuite) TestReadConfigUnregisteredToolsetConfig() {
 
 func (s *ToolsetConfigSuite) TestConfigDirPathInContext() {
 	var capturedDirPath string
-	RegisterToolsetConfig("test-toolset", func(ctx context.Context, primitive toml.Primitive, md toml.MetaData) (Extended, error) {
+	RegisterToolsetConfig("test-toolset", func(ctx context.Context, primitive toml.Primitive, md toml.MetaData) (configapi.Extended, error) {
 		capturedDirPath = ConfigDirPathFromContext(ctx)
 		var toolsetConfigForTest ToolsetConfigForTest
 		if err := md.PrimitiveDecode(primitive, &toolsetConfigForTest); err != nil {
@@ -299,7 +300,7 @@ func (s *ToolsetConfigSuite) TestStandaloneConfigDirWithExtendedConfig() {
 func (s *ToolsetConfigSuite) TestConfigDirPathInContextStandalone() {
 	// Test that configDirPath is correctly set in context for standalone --config-dir
 	var capturedDirPath string
-	RegisterToolsetConfig("test-toolset", func(ctx context.Context, primitive toml.Primitive, md toml.MetaData) (Extended, error) {
+	RegisterToolsetConfig("test-toolset", func(ctx context.Context, primitive toml.Primitive, md toml.MetaData) (configapi.Extended, error) {
 		capturedDirPath = ConfigDirPathFromContext(ctx)
 		var toolsetConfigForTest ToolsetConfigForTest
 		if err := md.PrimitiveDecode(primitive, &toolsetConfigForTest); err != nil {

pkg/http/http_test.go

@@ -26,6 +26,7 @@ import (
 	"k8s.io/klog/v2"
 	"k8s.io/klog/v2/textlogger"
 
+	configapi "github.com/containers/kubernetes-mcp-server/pkg/api/config"
 	"github.com/containers/kubernetes-mcp-server/pkg/config"
 	"github.com/containers/kubernetes-mcp-server/pkg/mcp"
 )
@@ -240,7 +241,7 @@ func TestHealthCheck(t *testing.T) {
 		})
 	})
 	// Health exposed even when require Authorization
-	testCaseWithContext(t, &httpContext{StaticConfig: &config.StaticConfig{RequireOAuth: true, ValidateToken: true, ClusterProviderStrategy: config.ClusterProviderKubeConfig}}, func(ctx *httpContext) {
+	testCaseWithContext(t, &httpContext{StaticConfig: &config.StaticConfig{RequireOAuth: true, ValidateToken: true, ClusterProviderStrategy: configapi.ClusterProviderKubeConfig}}, func(ctx *httpContext) {
 		resp, err := http.Get(fmt.Sprintf("http://%s/healthz", ctx.HttpAddress))
 		if err != nil {
 			t.Fatalf("Failed to get health check endpoint with OAuth: %v", err)
@@ -261,7 +262,7 @@ func TestWellKnownReverseProxy(t *testing.T) {
 		".well-known/openid-configuration",
 	}
 	// With No Authorization URL configured
-	testCaseWithContext(t, &httpContext{StaticConfig: &config.StaticConfig{RequireOAuth: true, ValidateToken: true, ClusterProviderStrategy: config.ClusterProviderKubeConfig}}, func(ctx *httpContext) {
+	testCaseWithContext(t, &httpContext{StaticConfig: &config.StaticConfig{RequireOAuth: true, ValidateToken: true, ClusterProviderStrategy: configapi.ClusterProviderKubeConfig}}, func(ctx *httpContext) {
 		for _, path := range cases {
 			resp, err := http.Get(fmt.Sprintf("http://%s/%s", ctx.HttpAddress, path))
 			t.Cleanup(func() { _ = resp.Body.Close() })
@@ -285,7 +286,7 @@ func TestWellKnownReverseProxy(t *testing.T) {
 		AuthorizationURL:        invalidPayloadServer.URL,
 		RequireOAuth:            true,
 		ValidateToken:           true,
-		ClusterProviderStrategy: config.ClusterProviderKubeConfig,
+		ClusterProviderStrategy: configapi.ClusterProviderKubeConfig,
 	}
 	testCaseWithContext(t, &httpContext{StaticConfig: invalidPayloadConfig}, func(ctx *httpContext) {
 		for _, path := range cases {
@@ -315,7 +316,7 @@ func TestWellKnownReverseProxy(t *testing.T) {
 		AuthorizationURL:        testServer.URL,
 		RequireOAuth:            true,
 		ValidateToken:           true,
-		ClusterProviderStrategy: config.ClusterProviderKubeConfig,
+		ClusterProviderStrategy: configapi.ClusterProviderKubeConfig,
 	}
 	testCaseWithContext(t, &httpContext{StaticConfig: staticConfig}, func(ctx *httpContext) {
 		for _, path := range cases {
@@ -365,7 +366,7 @@ func TestWellKnownHeaderPropagation(t *testing.T) {
 		AuthorizationURL:        testServer.URL,
 		RequireOAuth:            true,
 		ValidateToken:           true,
-		ClusterProviderStrategy: config.ClusterProviderKubeConfig,
+		ClusterProviderStrategy: configapi.ClusterProviderKubeConfig,
 	}
 	testCaseWithContext(t, &httpContext{StaticConfig: staticConfig}, func(ctx *httpContext) {
 		for _, path := range cases {
@@ -479,7 +480,7 @@ func TestWellKnownOverrides(t *testing.T) {
 		AuthorizationURL:        testServer.URL,
 		RequireOAuth:            true,
 		ValidateToken:           true,
-		ClusterProviderStrategy: config.ClusterProviderKubeConfig,
+		ClusterProviderStrategy: configapi.ClusterProviderKubeConfig,
 	}
 	// With Dynamic Client Registration disabled
 	disableDynamicRegistrationConfig := baseConfig

pkg/kiali/config.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 
 	"github.com/BurntSushi/toml"
+	configapi "github.com/containers/kubernetes-mcp-server/pkg/api/config"
 	"github.com/containers/kubernetes-mcp-server/pkg/config"
 )
 
@@ -20,7 +21,7 @@ type Config struct {
 	CertificateAuthority string `toml:"certificate_authority,omitempty"`
 }
 
-var _ config.Extended = (*Config)(nil)
+var _ configapi.Extended = (*Config)(nil)
 
 func (c *Config) Validate() error {
 	if c == nil {
@@ -45,7 +46,7 @@ func (c *Config) Validate() error {
 	return nil
 }
 
-func kialiToolsetParser(ctx context.Context, primitive toml.Primitive, md toml.MetaData) (config.Extended, error) {
+func kialiToolsetParser(ctx context.Context, primitive toml.Primitive, md toml.MetaData) (configapi.Extended, error) {
 	var cfg Config
 	if err := md.PrimitiveDecode(primitive, &cfg); err != nil {
 		return nil, err