Allow dynamically registered context endpoint to provide their defaults.

Previously an endpoint registered using `RegisterDefaultStoreEndpoints` would
not be taken into consideration by `resolveDefaultContext` and so could not
provide any details.

Resolve this by passing a `store.Config` to `resolveDefaultContext` and using
it to iterate over all registered endpoints. Any endpoint can ensure that their
type implements the new `EndpointDefaultResolver` in order to provide a default.

The Docker and Kubernetes endpoints are special cased, shortly the Kubernetes
one will be refactored to be dynamically registered.

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

Author: Ian Campbell

cli/command/cli.go

@@ -214,7 +214,7 @@ func (cli *DockerCli) Initialize(opts *cliflags.ClientOptions, ops ...Initialize
 	cli.contextStore = &ContextStoreWithDefault{
 		Store: baseContextStore,
 		Resolver: func() (*DefaultContext, error) {
-			return resolveDefaultContext(opts.Common, cli.ConfigFile(), cli.Err())
+			return resolveDefaultContext(opts.Common, cli.ConfigFile(), cli.contextStoreConfig, cli.Err())
 		},
 	}
 	cli.currentContext, err = resolveContextName(opts.Common, cli.configFile, cli.contextStore)
@@ -259,10 +259,11 @@ func (cli *DockerCli) Initialize(opts *cliflags.ClientOptions, ops ...Initialize
 
 // NewAPIClientFromFlags creates a new APIClient from command line flags
 func NewAPIClientFromFlags(opts *cliflags.CommonOptions, configFile *configfile.ConfigFile) (client.APIClient, error) {
+	storeConfig := defaultContextStoreConfig()
 	store := &ContextStoreWithDefault{
-		Store: store.New(cliconfig.ContextStoreDir(), defaultContextStoreConfig()),
+		Store: store.New(cliconfig.ContextStoreDir(), storeConfig),
 		Resolver: func() (*DefaultContext, error) {
-			return resolveDefaultContext(opts, configFile, ioutil.Discard)
+			return resolveDefaultContext(opts, configFile, storeConfig, ioutil.Discard)
 		},
 	}
 	contextName, err := resolveContextName(opts, configFile, store)

cli/command/defaultcontextstore.go

@@ -35,8 +35,16 @@ type ContextStoreWithDefault struct {
 	Resolver DefaultContextResolver
 }
 
+// EndpointDefaultResolver is implemented by any EndpointMeta object
+// which wants to be able to populate the store with whatever their default is.
+type EndpointDefaultResolver interface {
+	// ResolveDefault returns values suitable for storing in store.Metadata.Endpoints
+	// and store.ContextTLSData.Endpoints. If there is no default then returns nil, nil.
+	ResolveDefault() (interface{}, *store.EndpointTLSData)
+}
+
 // resolveDefaultContext creates a Metadata for the current CLI invocation parameters
-func resolveDefaultContext(opts *cliflags.CommonOptions, config *configfile.ConfigFile, stderr io.Writer) (*DefaultContext, error) {
+func resolveDefaultContext(opts *cliflags.CommonOptions, config *configfile.ConfigFile, storeconfig store.Config, stderr io.Writer) (*DefaultContext, error) {
 	stackOrchestrator, err := GetStackOrchestrator("", "", config.StackOrchestrator, stderr)
 	if err != nil {
 		return nil, err
@@ -78,6 +86,27 @@ func resolveDefaultContext(opts *cliflags.CommonOptions, config *configfile.Conf
 		}
 	}
 
+	if err := storeconfig.ForeachEndpointType(func(n string, get store.TypeGetter) error {
+		if n == docker.DockerEndpoint || n == kubernetes.KubernetesEndpoint { // handled above
+			return nil
+		}
+		ep := get()
+		if i, ok := ep.(EndpointDefaultResolver); ok {
+			meta, tls := i.ResolveDefault()
+			if meta == nil {
+				return nil
+			}
+			contextMetadata.Endpoints[n] = meta
+			if tls != nil {
+				contextTLSData.Endpoints[n] = *tls
+			}
+		}
+		// Nothing to be done
+		return nil
+	}); err != nil {
+		return nil, err
+	}
+
 	return &DefaultContext{Meta: contextMetadata, TLS: contextTLSData}, nil
 }
 

cli/command/defaultcontextstore_test.go

@@ -72,7 +72,7 @@ func TestDefaultContextInitializer(t *testing.T) {
 		TLSOptions: &tlsconfig.Options{
 			CAFile: "./testdata/ca.pem",
 		},
-	}, cli.ConfigFile(), cli.Err())
+	}, 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)