context: implement lazy loading, and other improvements

cli/command/cli.go

@@ -2,12 +2,14 @@ package command
 
 import (
 	"context"
+	"fmt"
 	"io"
 	"os"
 	"path/filepath"
 	"runtime"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/docker/cli/cli/config"
@@ -78,6 +80,8 @@ type DockerCli struct {
 	contentTrust       bool
 	contextStore       store.Store
 	currentContext     string
+	init               sync.Once
+	initErr            error
 	dockerEndpoint     docker.Endpoint
 	contextStoreConfig store.Config
 	initTimeout        time.Duration
@@ -91,6 +95,7 @@ func (cli *DockerCli) DefaultVersion() string {
 // CurrentVersion returns the API version currently negotiated, or the default
 // version otherwise.
 func (cli *DockerCli) CurrentVersion() string {
+	_ = cli.initialize()
 	if cli.client == nil {
 		return api.DefaultVersion
 	}
@@ -99,6 +104,10 @@ func (cli *DockerCli) CurrentVersion() string {
 
 // Client returns the APIClient
 func (cli *DockerCli) Client() client.APIClient {
+	if err := cli.initialize(); err != nil {
+		_, _ = fmt.Fprintf(cli.Err(), "Failed to initialize: %s\n", err)
+		os.Exit(1)
+	}
 	return cli.client
 }
 
@@ -143,7 +152,7 @@ func (cli *DockerCli) ConfigFile() *configfile.ConfigFile {
 // ServerInfo returns the server version details for the host this client is
 // connected to
 func (cli *DockerCli) ServerInfo() ServerInfo {
-	// TODO(thaJeztah) make ServerInfo() lazily load the info (ping only when needed)
+	_ = cli.initialize()
 	return cli.serverInfo
 }
 
@@ -203,8 +212,6 @@ func WithInitializeClient(makeClient func(dockerCli *DockerCli) (client.APIClien
 // Initialize the dockerCli runs initialization that must happen after command
 // line flags are parsed.
 func (cli *DockerCli) Initialize(opts *cliflags.ClientOptions, ops ...InitializeOpt) error {
-	var err error
-
 	for _, o := range ops {
 		if err := o(cli); err != nil {
 			return err
@@ -232,18 +239,6 @@ func (cli *DockerCli) Initialize(opts *cliflags.ClientOptions, ops ...Initialize
 			return ResolveDefaultContext(cli.options, cli.contextStoreConfig)
 		},
 	}
-	cli.dockerEndpoint, err = resolveDockerEndpoint(cli.contextStore, resolveContextName(opts, cli.configFile))
-	if err != nil {
-		return errors.Wrap(err, "unable to resolve docker endpoint")
-	}
-
-	if cli.client == nil {
-		cli.client, err = newAPIClientFromEndpoint(cli.dockerEndpoint, cli.configFile)
-		if err != nil {
-			return err
-		}
-	}
-	cli.initializeFromClient()
 	return nil
 }
 
@@ -282,6 +277,9 @@ func newAPIClientFromEndpoint(ep docker.Endpoint, configFile *configfile.ConfigF
 }
 
 func resolveDockerEndpoint(s store.Reader, contextName string) (docker.Endpoint, error) {
+	if s == nil {
+		return docker.Endpoint{}, fmt.Errorf("no context store initialized")
+	}
 	ctxMeta, err := s.GetMetadata(contextName)
 	if err != nil {
 		return docker.Endpoint{}, err
@@ -331,7 +329,7 @@ func (cli *DockerCli) getInitTimeout() time.Duration {
 
 func (cli *DockerCli) initializeFromClient() {
 	ctx := context.Background()
-	if !strings.HasPrefix(cli.DockerEndpoint().Host, "ssh://") {
+	if !strings.HasPrefix(cli.dockerEndpoint.Host, "ssh://") {
 		// @FIXME context.WithTimeout doesn't work with connhelper / ssh connections
 		// time="2020-04-10T10:16:26Z" level=warning msg="commandConn.CloseWrite: commandconn: failed to wait: signal: killed"
 		var cancel func()
@@ -428,9 +426,39 @@ func resolveContextName(opts *cliflags.ClientOptions, config *configfile.ConfigF
 
 // DockerEndpoint returns the current docker endpoint
 func (cli *DockerCli) DockerEndpoint() docker.Endpoint {
+	if err := cli.initialize(); err != nil {
+		// Note that we're not terminating here, as this function may be used
+		// in cases where we're able to continue.
+		_, _ = fmt.Fprintf(cli.Err(), "%v\n", cli.initErr)
+	}
 	return cli.dockerEndpoint
 }
 
+func (cli *DockerCli) getDockerEndPoint() (ep docker.Endpoint, err error) {
+	cn := cli.CurrentContext()
+	if cn == DefaultContextName {
+		return resolveDefaultDockerEndpoint(cli.options)
+	}
+	return resolveDockerEndpoint(cli.contextStore, cn)
+}
+
+func (cli *DockerCli) initialize() error {
+	cli.init.Do(func() {
+		cli.dockerEndpoint, cli.initErr = cli.getDockerEndPoint()
+		if cli.initErr != nil {
+			cli.initErr = errors.Wrap(cli.initErr, "unable to resolve docker endpoint")
+			return
+		}
+		if cli.client == nil {
+			if cli.client, cli.initErr = newAPIClientFromEndpoint(cli.dockerEndpoint, cli.configFile); cli.initErr != nil {
+				return
+			}
+		}
+		cli.initializeFromClient()
+	})
+	return cli.initErr
+}
+
 // Apply all the operation on the cli
 func (cli *DockerCli) Apply(ops ...DockerCliOption) error {
 	for _, op := range ops {

cli/command/cli_test.go

@@ -118,7 +118,7 @@ func (c *fakeClient) NegotiateAPIVersionPing(types.Ping) {
 }
 
 func TestInitializeFromClient(t *testing.T) {
-	defaultVersion := "v1.55"
+	const defaultVersion = "v1.55"
 
 	testcases := []struct {
 		doc            string
@@ -160,7 +160,8 @@ func TestInitializeFromClient(t *testing.T) {
 			}
 
 			cli := &DockerCli{client: apiclient}
-			cli.initializeFromClient()
+			err := cli.Initialize(flags.NewClientOptions())
+			assert.NilError(t, err)
 			assert.DeepEqual(t, cli.ServerInfo(), testcase.expectedServer)
 			assert.Equal(t, apiclient.negotiated, testcase.negotiated)
 		})
@@ -202,6 +203,7 @@ func TestInitializeFromClientHangs(t *testing.T) {
 		cli := &DockerCli{client: apiClient, initTimeout: time.Millisecond}
 		err := cli.Initialize(flags.NewClientOptions())
 		assert.Check(t, err)
+		cli.CurrentVersion()
 		close(initializedCh)
 	}()
 

cli/command/context/list.go

@@ -50,26 +50,54 @@ func runList(dockerCli command.Cli, opts *listOptions) error {
 	}
 	var (
 		curContext = dockerCli.CurrentContext()
+		curFound   bool
 		contexts   []*formatter.ClientContext
 	)
 	for _, rawMeta := range contextMap {
 		isCurrent := rawMeta.Name == curContext
+		if isCurrent {
+			curFound = true
+		}
 		meta, err := command.GetDockerContext(rawMeta)
 		if err != nil {
-			return err
+			// Add a stub-entry to the list, including the error-message
+			// indicating that the context couldn't be loaded.
+			contexts = append(contexts, &formatter.ClientContext{
+				Name:    rawMeta.Name,
+				Current: isCurrent,
+				Error:   err.Error(),
+			})
+			continue
 		}
+		var errMsg string
 		dockerEndpoint, err := docker.EndpointFromContext(rawMeta)
 		if err != nil {
-			return err
+			errMsg = err.Error()
 		}
 		desc := formatter.ClientContext{
 			Name:           rawMeta.Name,
 			Current:        isCurrent,
 			Description:    meta.Description,
 			DockerEndpoint: dockerEndpoint.Host,
+			Error:          errMsg,
 		}
 		contexts = append(contexts, &desc)
 	}
+	if !curFound {
+		// The currently specified context wasn't found. We add a stub-entry
+		// to the list, including the error-message indicating that the context
+		// wasn't found.
+		var errMsg string
+		_, err := dockerCli.ContextStore().GetMetadata(curContext)
+		if err != nil {
+			errMsg = err.Error()
+		}
+		contexts = append(contexts, &formatter.ClientContext{
+			Name:    curContext,
+			Current: true,
+			Error:   errMsg,
+		})
+	}
 	sort.Slice(contexts, func(i, j int) bool {
 		return sortorder.NaturalLess(contexts[i].Name, contexts[j].Name)
 	})

cli/command/context/list_test.go

@@ -39,3 +39,11 @@ func TestListQuiet(t *testing.T) {
 	assert.NilError(t, runList(cli, &listOptions{quiet: true}))
 	golden.Assert(t, cli.OutBuffer().String(), "quiet-list.golden")
 }
+
+func TestListError(t *testing.T) {
+	cli := makeFakeCli(t)
+	cli.SetCurrentContext("nosuchcontext")
+	cli.OutBuffer().Reset()
+	assert.NilError(t, runList(cli, &listOptions{}))
+	golden.Assert(t, cli.OutBuffer().String(), "list-with-error.golden")
+}

cli/command/context/testdata/list-with-error.golden

@@ -0,0 +1,3 @@
+NAME              DESCRIPTION                               DOCKER ENDPOINT               ERROR
+default           Current DOCKER_HOST based configuration   unix:///var/run/docker.sock   
+nosuchcontext *                                                                           context "nosuchcontext": context not found: …

cli/command/context/testdata/list.golden

@@ -1,5 +1,5 @@
-NAME        DESCRIPTION                               DOCKER ENDPOINT
-current *   description of current                    https://someswarmserver.example.com
-default     Current DOCKER_HOST based configuration   unix:///var/run/docker.sock
-other       description of other                      https://someswarmserver.example.com
-unset       description of unset                      https://someswarmserver.example.com
+NAME        DESCRIPTION                               DOCKER ENDPOINT                       ERROR
+current *   description of current                    https://someswarmserver.example.com   
+default     Current DOCKER_HOST based configuration   unix:///var/run/docker.sock           
+other       description of other                      https://someswarmserver.example.com   
+unset       description of unset                      https://someswarmserver.example.com   

cli/command/formatter/context.go

@@ -1,20 +1,22 @@
 package formatter
 
 const (
-	// ClientContextTableFormat is the default client context format
-	ClientContextTableFormat = "table {{.Name}}{{if .Current}} *{{end}}\t{{.Description}}\t{{.DockerEndpoint}}"
+	// ClientContextTableFormat is the default client context format.
+	ClientContextTableFormat = "table {{.Name}}{{if .Current}} *{{end}}\t{{.Description}}\t{{.DockerEndpoint}}\t{{.Error}}"
 
 	dockerEndpointHeader = "DOCKER ENDPOINT"
 	quietContextFormat   = "{{.Name}}"
+
+	maxErrLength = 45
 )
 
 // NewClientContextFormat returns a Format for rendering using a Context
 func NewClientContextFormat(source string, quiet bool) Format {
 	if quiet {
-		return Format(quietContextFormat)
+		return quietContextFormat
 	}
 	if source == TableFormatKey {
-		return Format(ClientContextTableFormat)
+		return ClientContextTableFormat
 	}
 	return Format(source)
 }
@@ -25,6 +27,7 @@ type ClientContext struct {
 	Description    string
 	DockerEndpoint string
 	Current        bool
+	Error          string
 }
 
 // ClientContextWrite writes formatted contexts using the Context
@@ -51,6 +54,7 @@ func newClientContextContext() *clientContextContext {
 		"Name":           NameHeader,
 		"Description":    DescriptionHeader,
 		"DockerEndpoint": dockerEndpointHeader,
+		"Error":          ErrorHeader,
 	}
 	return &ctx
 }
@@ -75,6 +79,12 @@ func (c *clientContextContext) DockerEndpoint() string {
 	return c.c.DockerEndpoint
 }
 
+// Error returns the truncated error (if any) that occurred when loading the context.
+func (c *clientContextContext) Error() string {
+	// TODO(thaJeztah) add "--no-trunc" option to context ls and set default to 30 cols to match "docker service ps"
+	return Ellipsis(c.c.Error, maxErrLength)
+}
+
 // KubernetesEndpoint returns the kubernetes endpoint.
 //
 // Deprecated: support for kubernetes endpoints in contexts has been removed, and this formatting option will always be empty.

cli/command/formatter/custom.go

@@ -16,6 +16,7 @@ const (
 	StatusHeader       = "STATUS"
 	PortsHeader        = "PORTS"
 	ImageHeader        = "IMAGE"
+	ErrorHeader        = "ERROR"
 	ContainerIDHeader  = "CONTAINER ID"
 )
 

cli/command/task/formatter.go

@@ -20,7 +20,6 @@ const (
 	taskIDHeader       = "ID"
 	desiredStateHeader = "DESIRED STATE"
 	currentStateHeader = "CURRENT STATE"
-	errorHeader        = "ERROR"
 
 	maxErrLength = 30
 )
@@ -61,7 +60,7 @@ func FormatWrite(ctx formatter.Context, tasks []swarm.Task, names map[string]str
 		"Node":         nodeHeader,
 		"DesiredState": desiredStateHeader,
 		"CurrentState": currentStateHeader,
-		"Error":        errorHeader,
+		"Error":        formatter.ErrorHeader,
 		"Ports":        formatter.PortsHeader,
 	}
 	return ctx.Write(&taskCtx, render)
@@ -124,11 +123,11 @@ func (c *taskContext) CurrentState() string {
 func (c *taskContext) Error() string {
 	// Trim and quote the error message.
 	taskErr := c.task.Status.Err
-	if c.trunc && len(taskErr) > maxErrLength {
-		taskErr = fmt.Sprintf("%s…", taskErr[:maxErrLength-1])
+	if c.trunc {
+		taskErr = formatter.Ellipsis(taskErr, maxErrLength)
 	}
 	if len(taskErr) > 0 {
-		taskErr = fmt.Sprintf("\"%s\"", taskErr)
+		taskErr = fmt.Sprintf(`"%s"`, taskErr)
 	}
 	return taskErr
 }

cli/context/store/metadatastore.go

@@ -59,7 +59,7 @@ func parseTypedOrMap(payload []byte, getter TypeGetter) (interface{}, error) {
 func (s *metadataStore) get(name string) (Metadata, error) {
 	m, err := s.getByID(contextdirOf(name))
 	if err != nil {
-		return m, errors.Wrapf(err, "load context %q", name)
+		return m, errors.Wrapf(err, "context %q", name)
 	}
 	return m, nil
 }
@@ -68,7 +68,7 @@ func (s *metadataStore) getByID(id contextdir) (Metadata, error) {
 	bytes, err := os.ReadFile(filepath.Join(s.contextDir(id), metaFile))
 	if err != nil {
 		if errors.Is(err, os.ErrNotExist) {
-			return Metadata{}, errdefs.NotFound(errors.Wrap(err, "context does not exist"))
+			return Metadata{}, errdefs.NotFound(errors.Wrap(err, "context not found"))
 		}
 		return Metadata{}, err
 	}

e2e/context/testdata/context-ls-notls.golden

@@ -1,3 +1,3 @@
-NAME        DESCRIPTION                               DOCKER ENDPOINT
-default *   Current DOCKER_HOST based configuration   unix:///var/run/docker.sock
-remote      my remote cluster                         ssh://someserver
+NAME        DESCRIPTION                               DOCKER ENDPOINT               ERROR
+default *   Current DOCKER_HOST based configuration   unix:///var/run/docker.sock   
+remote      my remote cluster                         ssh://someserver              

e2e/context/testdata/context-ls-tls.golden

@@ -1,3 +1,3 @@
-NAME        DESCRIPTION                               DOCKER ENDPOINT
-default *   Current DOCKER_HOST based configuration   unix:///var/run/docker.sock
-test                                                  unix:///var/run/docker.sock
+NAME        DESCRIPTION                               DOCKER ENDPOINT               ERROR
+default *   Current DOCKER_HOST based configuration   unix:///var/run/docker.sock   
+test                                                  unix:///var/run/docker.sock   

e2e/context/testdata/context-ls.golden

@@ -1,3 +1,3 @@
-NAME        DESCRIPTION                               DOCKER ENDPOINT
-default *   Current DOCKER_HOST based configuration   unix:///var/run/docker.sock
-remote      my remote cluster                         ssh://someserver
+NAME        DESCRIPTION                               DOCKER ENDPOINT               ERROR
+default *   Current DOCKER_HOST based configuration   unix:///var/run/docker.sock   
+remote      my remote cluster                         ssh://someserver