Dynamically register kubernetes context store endpoint type.

This removes the need for the core context code to import
`github.com/docker/cli/cli/context/kubernetes` which in turn reduces the
transitive import tree in this file to not pull in all of Kubernetes.

Note that this means that any calling code which is interested in the
kubernetes endpoint must import `github.com/docker/cli/cli/context/kubernetes`
itself somewhere in order to trigger the dynamic registration. In practice
anything which is interested in Kubernetes must import that package (e.g.
`./cli/command/context.list` does for the `EndpointFromContext` function) to do
anything useful, so this restriction is not too onerous.

As a special case a small amount of Kubernetes related logic remains in
`ResolveDefaultContext` to handle error handling when the stack orchestrator
includes Kubernetes. In order to avoid a circular import loop this hardcodes
the kube endpoint name.

Similarly to avoid an import loop the existing `TestDefaultContextInitializer`
cannot continue to unit test for the Kubernetes case, so that aspect of the
test is carved off into a very similar test in the kubernetes context package.

Lastly, note that the kubernetes endpoint is now modifiable via
`WithContextEndpointType`.

Signed-off-by: Ian Campbell <ijc@docker.com>

cli/command/cli.go

@@ -14,7 +14,6 @@ import (
 	"github.com/docker/cli/cli/config/configfile"
 	dcontext "github.com/docker/cli/cli/context"
 	"github.com/docker/cli/cli/context/docker"
-	kubecontext "github.com/docker/cli/cli/context/kubernetes"
 	"github.com/docker/cli/cli/context/store"
 	"github.com/docker/cli/cli/debug"
 	cliflags "github.com/docker/cli/cli/flags"
@@ -529,7 +528,6 @@ func resolveContextName(opts *cliflags.CommonOptions, config *configfile.ConfigF
 
 var defaultStoreEndpoints = []store.NamedTypeGetter{
 	store.EndpointTypeGetter(docker.DockerEndpoint, func() interface{} { return &docker.EndpointMeta{} }),
-	store.EndpointTypeGetter(kubecontext.KubernetesEndpoint, func() interface{} { return &kubecontext.EndpointMeta{} }),
 }
 
 // RegisterDefaultStoreEndpoints registers a new named endpoint

cli/command/cli_options.go

@@ -7,7 +7,6 @@ import (
 	"strconv"
 
 	"github.com/docker/cli/cli/context/docker"
-	"github.com/docker/cli/cli/context/kubernetes"
 	"github.com/docker/cli/cli/context/store"
 	"github.com/docker/cli/cli/streams"
 	clitypes "github.com/docker/cli/types"
@@ -97,7 +96,7 @@ func WithContainerizedClient(containerizedFn func(string) (clitypes.Containerize
 func WithContextEndpointType(endpointName string, endpointType store.TypeGetter) DockerCliOption {
 	return func(cli *DockerCli) error {
 		switch endpointName {
-		case docker.DockerEndpoint, kubernetes.KubernetesEndpoint:
+		case docker.DockerEndpoint:
 			return fmt.Errorf("cannot change %q endpoint type", endpointName)
 		}
 		cli.contextStoreConfig.SetEndpoint(endpointName, endpointType)

cli/command/defaultcontextstore.go

@@ -3,15 +3,11 @@ package command
 import (
 	"fmt"
 	"io"
-	"os"
-	"path/filepath"
 
 	"github.com/docker/cli/cli/config/configfile"
 	"github.com/docker/cli/cli/context/docker"
-	"github.com/docker/cli/cli/context/kubernetes"
 	"github.com/docker/cli/cli/context/store"
 	cliflags "github.com/docker/cli/cli/flags"
-	"github.com/docker/docker/pkg/homedir"
 	"github.com/pkg/errors"
 )
 
@@ -70,30 +66,22 @@ func ResolveDefaultContext(opts *cliflags.CommonOptions, config *configfile.Conf
 		contextTLSData.Endpoints[docker.DockerEndpoint] = *dockerEP.TLSData.ToStoreTLSData()
 	}
 
-	// Default context uses env-based kubeconfig for Kubernetes endpoint configuration
-	kubeconfig := os.Getenv("KUBECONFIG")
-	if kubeconfig == "" {
-		kubeconfig = filepath.Join(homedir.Get(), ".kube/config")
-	}
-	kubeEP, err := kubernetes.FromKubeConfig(kubeconfig, "", "")
-	if (stackOrchestrator == OrchestratorKubernetes || stackOrchestrator == OrchestratorAll) && err != nil {
-		return nil, errors.Wrapf(err, "default orchestrator is %s but kubernetes endpoint could not be found", stackOrchestrator)
-	}
-	if err == nil {
-		contextMetadata.Endpoints[kubernetes.KubernetesEndpoint] = kubeEP.EndpointMeta
-		if kubeEP.TLSData != nil {
-			contextTLSData.Endpoints[kubernetes.KubernetesEndpoint] = *kubeEP.TLSData.ToStoreTLSData()
-		}
-	}
+	// We open code the string "kubernetes" below because we
+	// cannot import KubernetesEndpoint from the corresponding
+	// package due to import loops.
+	wantKubernetesEP := stackOrchestrator == OrchestratorKubernetes || stackOrchestrator == OrchestratorAll
 
 	if err := storeconfig.ForeachEndpointType(func(n string, get store.TypeGetter) error {
-		if n == docker.DockerEndpoint || n == kubernetes.KubernetesEndpoint { // handled above
+		if n == docker.DockerEndpoint { // handled above
 			return nil
 		}
 		ep := get()
 		if i, ok := ep.(EndpointDefaultResolver); ok {
 			meta, tls := i.ResolveDefault()
 			if meta == nil {
+				if wantKubernetesEP && n == "kubernetes" {
+					return errors.Errorf("default orchestrator is %s but unable to resolve kubernetes endpoint", stackOrchestrator)
+				}
 				return nil
 			}
 			contextMetadata.Endpoints[n] = meta
@@ -107,6 +95,10 @@ func ResolveDefaultContext(opts *cliflags.CommonOptions, config *configfile.Conf
 		return nil, err
 	}
 
+	if _, ok := contextMetadata.Endpoints["kubernetes"]; wantKubernetesEP && !ok {
+		return nil, errors.Errorf("default orchestrator is %s but kubernetes endpoint could not be found", stackOrchestrator)
+	}
+
 	return &DefaultContext{Meta: contextMetadata, TLS: contextTLSData}, nil
 }
 

cli/command/defaultcontextstore_test.go

@@ -8,7 +8,6 @@ import (
 
 	"github.com/docker/cli/cli/config/configfile"
 	"github.com/docker/cli/cli/context/docker"
-	"github.com/docker/cli/cli/context/kubernetes"
 	"github.com/docker/cli/cli/context/store"
 	cliflags "github.com/docker/cli/cli/flags"
 	"github.com/docker/go-connections/tlsconfig"
@@ -63,9 +62,8 @@ func TestDefaultContextInitializer(t *testing.T) {
 	cli, err := NewDockerCli()
 	assert.NilError(t, err)
 	defer env.Patch(t, "DOCKER_HOST", "ssh://someswarmserver")()
-	defer env.Patch(t, "KUBECONFIG", "./testdata/test-kubeconfig")()
 	cli.configFile = &configfile.ConfigFile{
-		StackOrchestrator: "all",
+		StackOrchestrator: "swarm",
 	}
 	ctx, err := ResolveDefaultContext(&cliflags.CommonOptions{
 		TLS: true,
@@ -75,10 +73,9 @@ func TestDefaultContextInitializer(t *testing.T) {
 	}, cli.ConfigFile(), DefaultContextStoreConfig(), cli.Err())
 	assert.NilError(t, err)
 	assert.Equal(t, "default", ctx.Meta.Name)
-	assert.Equal(t, OrchestratorAll, ctx.Meta.Metadata.(DockerContext).StackOrchestrator)
+	assert.Equal(t, OrchestratorSwarm, ctx.Meta.Metadata.(DockerContext).StackOrchestrator)
 	assert.DeepEqual(t, "ssh://someswarmserver", ctx.Meta.Endpoints[docker.DockerEndpoint].(docker.EndpointMeta).Host)
 	golden.Assert(t, string(ctx.TLS.Endpoints[docker.DockerEndpoint].Files["ca.pem"]), "ca.pem")
-	assert.DeepEqual(t, "zoinx", ctx.Meta.Endpoints[kubernetes.KubernetesEndpoint].(kubernetes.EndpointMeta).DefaultNamespace)
 }
 
 func TestExportDefaultImport(t *testing.T) {

cli/context/kubernetes/load.go

@@ -1,9 +1,14 @@
 package kubernetes
 
 import (
+	"os"
+	"path/filepath"
+
+	"github.com/docker/cli/cli/command"
 	"github.com/docker/cli/cli/context"
 	"github.com/docker/cli/cli/context/store"
 	api "github.com/docker/compose-on-kubernetes/api"
+	"github.com/docker/docker/pkg/homedir"
 	"k8s.io/client-go/tools/clientcmd"
 	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
 )
@@ -17,6 +22,8 @@ type EndpointMeta struct {
 	Exec             *clientcmdapi.ExecConfig         `json:",omitempty"`
 }
 
+var _ command.EndpointDefaultResolver = &EndpointMeta{}
+
 // Endpoint is a typed wrapper around a context-store generic endpoint describing
 // a Kubernetes endpoint, with TLS data
 type Endpoint struct {
@@ -24,6 +31,12 @@ type Endpoint struct {
 	TLSData *context.TLSData
 }
 
+func init() {
+	command.RegisterDefaultStoreEndpoints(
+		store.EndpointTypeGetter(KubernetesEndpoint, func() interface{} { return &EndpointMeta{} }),
+	)
+}
+
 // WithTLSData loads TLS materials for the endpoint
 func (c *EndpointMeta) WithTLSData(s store.Reader, contextName string) (Endpoint, error) {
 	tlsData, err := context.LoadTLSData(s, contextName, KubernetesEndpoint)
@@ -61,6 +74,25 @@ func (c *Endpoint) KubernetesConfig() clientcmd.ClientConfig {
 	return clientcmd.NewDefaultClientConfig(*cfg, &clientcmd.ConfigOverrides{})
 }
 
+// ResolveDefault returns endpoint metadata for the default Kubernetes
+// endpoint, which is derived from the env-based kubeconfig.
+func (c *EndpointMeta) ResolveDefault() (interface{}, *store.EndpointTLSData) {
+	kubeconfig := os.Getenv("KUBECONFIG")
+	if kubeconfig == "" {
+		kubeconfig = filepath.Join(homedir.Get(), ".kube/config")
+	}
+	kubeEP, err := FromKubeConfig(kubeconfig, "", "")
+	if err != nil {
+		return nil, nil
+	}
+
+	var tls *store.EndpointTLSData
+	if kubeEP.TLSData != nil {
+		tls = kubeEP.TLSData.ToStoreTLSData()
+	}
+	return kubeEP.EndpointMeta, tls
+}
+
 // EndpointFromContext extracts kubernetes endpoint info from current context
 func EndpointFromContext(metadata store.Metadata) *EndpointMeta {
 	ep, ok := metadata.Endpoints[KubernetesEndpoint]

cli/context/kubernetes/load_test.go

@@ -0,0 +1,25 @@
+package kubernetes
+
+import (
+	"testing"
+
+	"github.com/docker/cli/cli/command"
+	"github.com/docker/cli/cli/config/configfile"
+	cliflags "github.com/docker/cli/cli/flags"
+	"gotest.tools/assert"
+	"gotest.tools/env"
+)
+
+func TestDefaultContextInitializer(t *testing.T) {
+	cli, err := command.NewDockerCli()
+	assert.NilError(t, err)
+	defer env.Patch(t, "KUBECONFIG", "./testdata/test-kubeconfig")()
+	configFile := &configfile.ConfigFile{
+		StackOrchestrator: "all",
+	}
+	ctx, err := command.ResolveDefaultContext(&cliflags.CommonOptions{}, configFile, command.DefaultContextStoreConfig(), cli.Err())
+	assert.NilError(t, err)
+	assert.Equal(t, "default", ctx.Meta.Name)
+	assert.Equal(t, command.OrchestratorAll, ctx.Meta.Metadata.(command.DockerContext).StackOrchestrator)
+	assert.DeepEqual(t, "zoinx", ctx.Meta.Endpoints[KubernetesEndpoint].(EndpointMeta).DefaultNamespace)
+}