Split the context store interface

This is to make it easier to implement support for exporting contexts in
3rd party code, or to create mocks in tests.

2 exemples where it simplify things:
- docker-app desktop-specific context decorator (which rewrites parts of
the docker context to simplify UX when using on Docker Desktop contexts)
- ucp for including a context in the connection bundle

Signed-off-by: Simon Ferquel <simon.ferquel@docker.com>

cli/context/docker/load.go

@@ -31,7 +31,7 @@ type Endpoint struct {
 }
 
 // WithTLSData loads TLS materials for the endpoint
-func WithTLSData(s store.Store, contextName string, m EndpointMeta) (Endpoint, error) {
+func WithTLSData(s store.Reader, contextName string, m EndpointMeta) (Endpoint, error) {
 	tlsData, err := context.LoadTLSData(s, contextName, DockerEndpoint)
 	if err != nil {
 		return Endpoint{}, err

cli/context/kubernetes/endpoint_test.go

@@ -104,22 +104,22 @@ func TestSaveLoadContexts(t *testing.T) {
 
 	rawNoTLSEP, err := rawNoTLS.WithTLSData(store, "raw-notls")
 	assert.NilError(t, err)
-	checkClientConfig(t, store, rawNoTLSEP, "https://test", "test", nil, nil, nil, false)
+	checkClientConfig(t, rawNoTLSEP, "https://test", "test", nil, nil, nil, false)
 	rawNoTLSSkipEP, err := rawNoTLSSkip.WithTLSData(store, "raw-notls-skip")
 	assert.NilError(t, err)
-	checkClientConfig(t, store, rawNoTLSSkipEP, "https://test", "test", nil, nil, nil, true)
+	checkClientConfig(t, rawNoTLSSkipEP, "https://test", "test", nil, nil, nil, true)
 	rawTLSEP, err := rawTLS.WithTLSData(store, "raw-tls")
 	assert.NilError(t, err)
-	checkClientConfig(t, store, rawTLSEP, "https://test", "test", []byte("ca"), []byte("cert"), []byte("key"), true)
+	checkClientConfig(t, rawTLSEP, "https://test", "test", []byte("ca"), []byte("cert"), []byte("key"), true)
 	embededDefaultEP, err := embededDefault.WithTLSData(store, "embed-default-context")
 	assert.NilError(t, err)
-	checkClientConfig(t, store, embededDefaultEP, "https://server1", "namespace1", nil, []byte("cert"), []byte("key"), true)
+	checkClientConfig(t, embededDefaultEP, "https://server1", "namespace1", nil, []byte("cert"), []byte("key"), true)
 	embededContext2EP, err := embededContext2.WithTLSData(store, "embed-context2")
 	assert.NilError(t, err)
-	checkClientConfig(t, store, embededContext2EP, "https://server2", "namespace-override", []byte("ca"), []byte("cert"), []byte("key"), false)
+	checkClientConfig(t, embededContext2EP, "https://server2", "namespace-override", []byte("ca"), []byte("cert"), []byte("key"), false)
 }
 
-func checkClientConfig(t *testing.T, s store.Store, ep Endpoint, server, namespace string, ca, cert, key []byte, skipTLSVerify bool) {
+func checkClientConfig(t *testing.T, ep Endpoint, server, namespace string, ca, cert, key []byte, skipTLSVerify bool) {
 	config := ep.KubernetesConfig()
 	cfg, err := config.ClientConfig()
 	assert.NilError(t, err)
@@ -132,7 +132,7 @@ func checkClientConfig(t *testing.T, s store.Store, ep Endpoint, server, namespa
 	assert.Equal(t, skipTLSVerify, cfg.Insecure)
 }
 
-func save(s store.Store, ep Endpoint, name string) error {
+func save(s store.Writer, ep Endpoint, name string) error {
 	meta := store.ContextMetadata{
 		Endpoints: map[string]interface{}{
 			KubernetesEndpoint: ep.EndpointMeta,

cli/context/kubernetes/load.go

@@ -25,7 +25,7 @@ type Endpoint struct {
 }
 
 // WithTLSData loads TLS materials for the endpoint
-func (c *EndpointMeta) WithTLSData(s store.Store, contextName string) (Endpoint, error) {
+func (c *EndpointMeta) WithTLSData(s store.Reader, contextName string) (Endpoint, error) {
 	tlsData, err := context.LoadTLSData(s, contextName, KubernetesEndpoint)
 	if err != nil {
 		return Endpoint{}, err
@@ -77,7 +77,7 @@ func EndpointFromContext(metadata store.ContextMetadata) *EndpointMeta {
 // ConfigFromContext resolves a kubernetes client config for the specified context.
 // If kubeconfigOverride is specified, use this config file instead of the context defaults.ConfigFromContext
 // if command.ContextDockerHost is specified as the context name, fallsback to the default user's kubeconfig file
-func ConfigFromContext(name string, s store.Store) (clientcmd.ClientConfig, error) {
+func ConfigFromContext(name string, s store.Reader) (clientcmd.ClientConfig, error) {
 	ctxMeta, err := s.GetContextMetadata(name)
 	if err != nil {
 		return nil, err

cli/context/store/store.go

@@ -18,17 +18,49 @@ import (
 
 // Store provides a context store for easily remembering endpoints configuration
 type Store interface {
-	ListContexts() ([]ContextMetadata, error)
-	CreateOrUpdateContext(meta ContextMetadata) error
-	RemoveContext(name string) error
+	Reader
+	Lister
+	Writer
+	StorageInfo
+}
+
+// Reader provides read-only (without list) access to context data
+type Reader interface {
 	GetContextMetadata(name string) (ContextMetadata, error)
-	ResetContextTLSMaterial(name string, data *ContextTLSData) error
-	ResetContextEndpointTLSMaterial(contextName string, endpointName string, data *EndpointTLSData) error
 	ListContextTLSFiles(name string) (map[string]EndpointFiles, error)
 	GetContextTLSData(contextName, endpointName, fileName string) ([]byte, error)
+}
+
+// Lister provides listing of contexts
+type Lister interface {
+	ListContexts() ([]ContextMetadata, error)
+}
+
+// ReaderLister combines Reader and Lister interfaces
+type ReaderLister interface {
+	Reader
+	Lister
+}
+
+// StorageInfo provides more information about storage details of contexts
+type StorageInfo interface {
 	GetContextStorageInfo(contextName string) ContextStorageInfo
 }
 
+// Writer provides write access to context data
+type Writer interface {
+	CreateOrUpdateContext(meta ContextMetadata) error
+	RemoveContext(name string) error
+	ResetContextTLSMaterial(name string, data *ContextTLSData) error
+	ResetContextEndpointTLSMaterial(contextName string, endpointName string, data *EndpointTLSData) error
+}
+
+// ReaderWriter combines Reader and Writer interfaces
+type ReaderWriter interface {
+	Reader
+	Writer
+}
+
 // ContextMetadata contains metadata about a context and its endpoints
 type ContextMetadata struct {
 	Name      string                 `json:",omitempty"`
@@ -151,7 +183,7 @@ func (s *store) GetContextStorageInfo(contextName string) ContextStorageInfo {
 // Export exports an existing namespace into an opaque data stream
 // This stream is actually a tarball containing context metadata and TLS materials, but it does
 // not map 1:1 the layout of the context store (don't try to restore it manually without calling store.Import)
-func Export(name string, s Store) io.ReadCloser {
+func Export(name string, s Reader) io.ReadCloser {
 	reader, writer := io.Pipe()
 	go func() {
 		tw := tar.NewWriter(writer)
@@ -228,7 +260,7 @@ func Export(name string, s Store) io.ReadCloser {
 }
 
 // Import imports an exported context into a store
-func Import(name string, s Store, reader io.Reader) error {
+func Import(name string, s Writer, reader io.Reader) error {
 	tr := tar.NewReader(reader)
 	tlsData := ContextTLSData{
 		Endpoints: map[string]EndpointTLSData{},

cli/context/tlsdata.go

@@ -42,7 +42,7 @@ func (data *TLSData) ToStoreTLSData() *store.EndpointTLSData {
 }
 
 // LoadTLSData loads TLS data from the store
-func LoadTLSData(s store.Store, contextName, endpointName string) (*TLSData, error) {
+func LoadTLSData(s store.Reader, contextName, endpointName string) (*TLSData, error) {
 	tlsFiles, err := s.ListContextTLSFiles(contextName)
 	if err != nil {
 		return nil, errors.Wrapf(err, "failed to retrieve context tls files for context %q", contextName)