assorted cleanups: use Println, rename vars for consistency

cli-plugins/examples/helloworld/main.go

@@ -12,24 +12,24 @@ import (
 )
 
 func main() {
-	plugin.Run(func(dockerCli command.Cli) *cobra.Command {
+	plugin.Run(func(dockerCLI command.Cli) *cobra.Command {
 		goodbye := &cobra.Command{
 			Use:   "goodbye",
 			Short: "Say Goodbye instead of Hello",
 			Run: func(cmd *cobra.Command, _ []string) {
-				fmt.Fprintln(dockerCli.Out(), "Goodbye World!")
+				_, _ = fmt.Fprintln(dockerCLI.Out(), "Goodbye World!")
 			},
 		}
 		apiversion := &cobra.Command{
 			Use:   "apiversion",
 			Short: "Print the API version of the server",
 			RunE: func(_ *cobra.Command, _ []string) error {
-				cli := dockerCli.Client()
-				ping, err := cli.Ping(context.Background())
+				apiClient := dockerCLI.Client()
+				ping, err := apiClient.Ping(context.Background())
 				if err != nil {
 					return err
 				}
-				fmt.Println(ping.APIVersion)
+				_, _ = fmt.Println(ping.APIVersion)
 				return nil
 			},
 		}
@@ -38,7 +38,7 @@ func main() {
 			Use:   "exitstatus2",
 			Short: "Exit with status 2",
 			RunE: func(_ *cobra.Command, _ []string) error {
-				fmt.Fprintln(dockerCli.Err(), "Exiting with error status 2")
+				_, _ = fmt.Fprintln(dockerCLI.Err(), "Exiting with error status 2")
 				os.Exit(2)
 				return nil
 			},
@@ -56,33 +56,33 @@ func main() {
 					return err
 				}
 				if preRun {
-					fmt.Fprintf(dockerCli.Err(), "Plugin PersistentPreRunE called")
+					_, _ = fmt.Fprintln(dockerCLI.Err(), "Plugin PersistentPreRunE called")
 				}
 				return nil
 			},
 			RunE: func(cmd *cobra.Command, args []string) error {
 				if debug {
-					fmt.Fprintf(dockerCli.Err(), "Plugin debug mode enabled")
+					_, _ = fmt.Fprintln(dockerCLI.Err(), "Plugin debug mode enabled")
 				}
 
 				switch optContext {
 				case "Christmas":
-					fmt.Fprintf(dockerCli.Out(), "Merry Christmas!\n")
+					_, _ = fmt.Fprintln(dockerCLI.Out(), "Merry Christmas!")
 					return nil
 				case "":
 					// nothing
 				}
 
 				if who == "" {
-					who, _ = dockerCli.ConfigFile().PluginConfig("helloworld", "who")
+					who, _ = dockerCLI.ConfigFile().PluginConfig("helloworld", "who")
 				}
 				if who == "" {
 					who = "World"
 				}
 
-				fmt.Fprintf(dockerCli.Out(), "Hello %s!\n", who)
-				dockerCli.ConfigFile().SetPluginConfig("helloworld", "lastwho", who)
-				return dockerCli.ConfigFile().Save()
+				_, _ = fmt.Fprintln(dockerCLI.Out(), "Hello", who)
+				dockerCLI.ConfigFile().SetPluginConfig("helloworld", "lastwho", who)
+				return dockerCLI.ConfigFile().Save()
 			},
 		}
 

cli-plugins/hooks/printer.go

@@ -11,8 +11,8 @@ func PrintNextSteps(out io.Writer, messages []string) {
 	if len(messages) == 0 {
 		return
 	}
-	fmt.Fprintln(out, aec.Bold.Apply("\nWhat's next:"))
+	_, _ = fmt.Fprintln(out, aec.Bold.Apply("\nWhat's next:"))
 	for _, n := range messages {
-		_, _ = fmt.Fprintf(out, "    %s\n", n)
+		_, _ = fmt.Fprintln(out, "   ", n)
 	}
 }

cli/command/checkpoint/create.go

@@ -40,8 +40,8 @@ func newCreateCommand(dockerCli command.Cli) *cobra.Command {
 	return cmd
 }
 
-func runCreate(ctx context.Context, dockerCli command.Cli, opts createOptions) error {
-	err := dockerCli.Client().CheckpointCreate(ctx, opts.container, checkpoint.CreateOptions{
+func runCreate(ctx context.Context, dockerCLI command.Cli, opts createOptions) error {
+	err := dockerCLI.Client().CheckpointCreate(ctx, opts.container, checkpoint.CreateOptions{
 		CheckpointID:  opts.checkpoint,
 		CheckpointDir: opts.checkpointDir,
 		Exit:          !opts.leaveRunning,
@@ -50,6 +50,6 @@ func runCreate(ctx context.Context, dockerCli command.Cli, opts createOptions) e
 		return err
 	}
 
-	fmt.Fprintf(dockerCli.Out(), "%s\n", opts.checkpoint)
+	_, _ = fmt.Fprintln(dockerCLI.Out(), opts.checkpoint)
 	return nil
 }

cli/command/cli.go

@@ -114,7 +114,7 @@ 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)
+		_, _ = fmt.Fprintln(cli.Err(), "Failed to initialize:", err)
 		os.Exit(1)
 	}
 	return cli.client
@@ -475,7 +475,7 @@ 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)
+		_, _ = fmt.Fprintln(cli.Err(), cli.initErr)
 	}
 	return cli.dockerEndpoint
 }

cli/command/container/cp.go

@@ -129,13 +129,12 @@ func NewCopyCommand(dockerCli command.Cli) *cobra.Command {
 		Use: `cp [OPTIONS] CONTAINER:SRC_PATH DEST_PATH|-
 	docker cp [OPTIONS] SRC_PATH|- CONTAINER:DEST_PATH`,
 		Short: "Copy files/folders between a container and the local filesystem",
-		Long: strings.Join([]string{
-			"Copy files/folders between a container and the local filesystem\n",
-			"\nUse '-' as the source to read a tar archive from stdin\n",
-			"and extract it to a directory destination in a container.\n",
-			"Use '-' as the destination to stream a tar archive of a\n",
-			"container source to stdout.",
-		}, ""),
+		Long: `Copy files/folders between a container and the local filesystem
+
+Use '-' as the source to read a tar archive from stdin
+and extract it to a directory destination in a container.
+Use '-' as the destination to stream a tar archive of a
+container source to stdout.`,
 		Args: cli.ExactArgs(2),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			if args[0] == "" {

cli/command/container/create.go

@@ -274,7 +274,7 @@ func createContainer(ctx context.Context, dockerCli command.Cli, containerCfg *c
 		if errdefs.IsNotFound(err) && namedRef != nil && options.pull == PullImageMissing {
 			if !options.quiet {
 				// we don't want to write to stdout anything apart from container.ID
-				fmt.Fprintf(dockerCli.Err(), "Unable to find image '%s' locally\n", reference.FamiliarString(namedRef))
+				_, _ = fmt.Fprintf(dockerCli.Err(), "Unable to find image '%s' locally\n", reference.FamiliarString(namedRef))
 			}
 
 			if err := pullAndTagImage(); err != nil {
@@ -292,15 +292,15 @@ func createContainer(ctx context.Context, dockerCli command.Cli, containerCfg *c
 	}
 
 	for _, w := range response.Warnings {
-		_, _ = fmt.Fprintf(dockerCli.Err(), "WARNING: %s\n", w)
+		_, _ = fmt.Fprintln(dockerCli.Err(), "WARNING:", w)
 	}
 	err = containerIDFile.Write(response.ID)
 	return response.ID, err
 }
 
 func warnOnOomKillDisable(hostConfig container.HostConfig, stderr io.Writer) {
 	if hostConfig.OomKillDisable != nil && *hostConfig.OomKillDisable && hostConfig.Memory == 0 {
-		fmt.Fprintln(stderr, "WARNING: Disabling the OOM killer on containers without setting a '-m/--memory' limit may be dangerous.")
+		_, _ = fmt.Fprintln(stderr, "WARNING: Disabling the OOM killer on containers without setting a '-m/--memory' limit may be dangerous.")
 	}
 }
 
@@ -309,7 +309,7 @@ func warnOnOomKillDisable(hostConfig container.HostConfig, stderr io.Writer) {
 func warnOnLocalhostDNS(hostConfig container.HostConfig, stderr io.Writer) {
 	for _, dnsIP := range hostConfig.DNS {
 		if isLocalhost(dnsIP) {
-			fmt.Fprintf(stderr, "WARNING: Localhost DNS setting (--dns=%s) may fail in containers.\n", dnsIP)
+			_, _ = fmt.Fprintf(stderr, "WARNING: Localhost DNS setting (--dns=%s) may fail in containers.\n", dnsIP)
 			return
 		}
 	}

cli/command/container/stats.go

@@ -299,7 +299,7 @@ func RunStats(ctx context.Context, dockerCLI command.Cli, options *StatsOptions)
 			for _, line := range strings.Split(statsTextBuffer.String(), "\n") {
 				// In case the new text is shorter than the one we are writing over,
 				// we'll append the "erase line" escape sequence to clear the remaining text.
-				_, _ = fmt.Fprint(&statsTextBuffer, line, "\033[K\n")
+				_, _ = fmt.Fprintln(&statsTextBuffer, line, "\033[K")
 			}
 
 			// We might have fewer containers than before, so let's clear the remaining text

cli/command/context/create.go

@@ -34,11 +34,11 @@ func longCreateDescription() string {
 	buf := bytes.NewBuffer(nil)
 	buf.WriteString("Create a context\n\nDocker endpoint config:\n\n")
 	tw := tabwriter.NewWriter(buf, 20, 1, 3, ' ', 0)
-	fmt.Fprintln(tw, "NAME\tDESCRIPTION")
+	_, _ = fmt.Fprintln(tw, "NAME\tDESCRIPTION")
 	for _, d := range dockerConfigKeysDescriptions {
-		fmt.Fprintf(tw, "%s\t%s\n", d.name, d.description)
+		_, _ = fmt.Fprintf(tw, "%s\t%s\n", d.name, d.description)
 	}
-	tw.Flush()
+	_ = tw.Flush()
 	buf.WriteString("\nExample:\n\n$ docker context create my-context --description \"some description\" --docker \"host=tcp://myserver:2376,ca=~/ca-file,cert=~/cert-file,key=~/key-file\"\n")
 	return buf.String()
 }
@@ -79,8 +79,8 @@ func RunCreate(dockerCLI command.Cli, o *CreateOptions) error {
 		err = createNewContext(s, o)
 	}
 	if err == nil {
-		fmt.Fprintln(dockerCLI.Out(), o.Name)
-		fmt.Fprintf(dockerCLI.Err(), "Successfully created context %q\n", o.Name)
+		_, _ = fmt.Fprintln(dockerCLI.Out(), o.Name)
+		_, _ = fmt.Fprintf(dockerCLI.Err(), "Successfully created context %q\n", o.Name)
 	}
 	return err
 }

cli/command/context/import.go

@@ -45,7 +45,7 @@ func RunImport(dockerCli command.Cli, name string, source string) error {
 		return err
 	}
 
-	fmt.Fprintln(dockerCli.Out(), name)
-	fmt.Fprintf(dockerCli.Err(), "Successfully imported context %q\n", name)
+	_, _ = fmt.Fprintln(dockerCli.Out(), name)
+	_, _ = fmt.Fprintf(dockerCli.Err(), "Successfully imported context %q\n", name)
 	return nil
 }

cli/command/context/update.go

@@ -24,11 +24,11 @@ func longUpdateDescription() string {
 	buf := bytes.NewBuffer(nil)
 	buf.WriteString("Update a context\n\nDocker endpoint config:\n\n")
 	tw := tabwriter.NewWriter(buf, 20, 1, 3, ' ', 0)
-	fmt.Fprintln(tw, "NAME\tDESCRIPTION")
+	_, _ = fmt.Fprintln(tw, "NAME\tDESCRIPTION")
 	for _, d := range dockerConfigKeysDescriptions {
-		fmt.Fprintf(tw, "%s\t%s\n", d.name, d.description)
+		_, _ = fmt.Fprintf(tw, "%s\t%s\n", d.name, d.description)
 	}
-	tw.Flush()
+	_ = tw.Flush()
 	buf.WriteString("\nExample:\n\n$ docker context update my-context --description \"some description\" --docker \"host=tcp://myserver:2376,ca=~/ca-file,cert=~/cert-file,key=~/key-file\"\n")
 	return buf.String()
 }
@@ -93,8 +93,8 @@ func RunUpdate(dockerCLI command.Cli, o *UpdateOptions) error {
 		}
 	}
 
-	fmt.Fprintln(dockerCLI.Out(), o.Name)
-	fmt.Fprintf(dockerCLI.Err(), "Successfully updated context %q\n", o.Name)
+	_, _ = fmt.Fprintln(dockerCLI.Out(), o.Name)
+	_, _ = fmt.Fprintf(dockerCLI.Err(), "Successfully updated context %q\n", o.Name)
 	return nil
 }
 

cli/command/context/use.go

@@ -24,19 +24,19 @@ func newUseCommand(dockerCli command.Cli) *cobra.Command {
 }
 
 // RunUse set the current Docker context
-func RunUse(dockerCli command.Cli, name string) error {
+func RunUse(dockerCLI command.Cli, name string) error {
 	// configValue uses an empty string for "default"
 	var configValue string
 	if name != command.DefaultContextName {
 		if err := store.ValidateContextName(name); err != nil {
 			return err
 		}
-		if _, err := dockerCli.ContextStore().GetMetadata(name); err != nil {
+		if _, err := dockerCLI.ContextStore().GetMetadata(name); err != nil {
 			return err
 		}
 		configValue = name
 	}
-	dockerConfig := dockerCli.ConfigFile()
+	dockerConfig := dockerCLI.ConfigFile()
 	// Avoid updating the config-file if nothing changed. This also prevents
 	// creating the file and config-directory if the default is used and
 	// no config-file existed yet.
@@ -46,10 +46,10 @@ func RunUse(dockerCli command.Cli, name string) error {
 			return err
 		}
 	}
-	fmt.Fprintln(dockerCli.Out(), name)
-	fmt.Fprintf(dockerCli.Err(), "Current context is now %q\n", name)
+	_, _ = fmt.Fprintln(dockerCLI.Out(), name)
+	_, _ = fmt.Fprintf(dockerCLI.Err(), "Current context is now %q\n", name)
 	if name != command.DefaultContextName && os.Getenv(client.EnvOverrideHost) != "" {
-		fmt.Fprintf(dockerCli.Err(), "Warning: %[1]s environment variable overrides the active context. "+
+		_, _ = fmt.Fprintf(dockerCLI.Err(), "Warning: %[1]s environment variable overrides the active context. "+
 			"To use %[2]q, either set the global --context flag, or unset %[1]s environment variable.\n", client.EnvOverrideHost, name)
 	}
 	return nil

cli/command/formatter/disk_usage.go

@@ -237,7 +237,7 @@ func (ctx *DiskUsageContext) verboseWriteTable(duc *diskUsageContext) error {
 	if err != nil {
 		return err
 	}
-	ctx.Output.Write([]byte("\nLocal Volumes space usage:\n\n"))
+	_, _ = ctx.Output.Write([]byte("\nLocal Volumes space usage:\n\n"))
 	for _, v := range duc.Volumes {
 		if err := ctx.contextFormat(tmpl, v); err != nil {
 			return err
@@ -249,7 +249,7 @@ func (ctx *DiskUsageContext) verboseWriteTable(duc *diskUsageContext) error {
 	if err != nil {
 		return err
 	}
-	fmt.Fprintf(ctx.Output, "\nBuild cache usage: %s\n\n", units.HumanSize(float64(ctx.BuilderSize)))
+	_, _ = fmt.Fprintf(ctx.Output, "\nBuild cache usage: %s\n\n", units.HumanSize(float64(ctx.BuilderSize)))
 	for _, v := range duc.BuildCache {
 		if err := ctx.contextFormat(tmpl, v); err != nil {
 			return err

cli/command/image/pull.go

@@ -66,7 +66,7 @@ func RunPull(ctx context.Context, dockerCLI command.Cli, opts PullOptions) error
 	case !opts.all && reference.IsNameOnly(distributionRef):
 		distributionRef = reference.TagNameOnly(distributionRef)
 		if tagged, ok := distributionRef.(reference.Tagged); ok && !opts.quiet {
-			fmt.Fprintf(dockerCLI.Out(), "Using default tag: %s\n", tagged.Tag())
+			_, _ = fmt.Fprintln(dockerCLI.Out(), "Using default tag:", tagged.Tag())
 		}
 	}
 
@@ -88,6 +88,6 @@ func RunPull(ctx context.Context, dockerCLI command.Cli, opts PullOptions) error
 		}
 		return err
 	}
-	fmt.Fprintln(dockerCLI.Out(), imgRefAndAuth.Reference().String())
+	_, _ = fmt.Fprintln(dockerCLI.Out(), imgRefAndAuth.Reference().String())
 	return nil
 }

cli/command/image/push.go

@@ -101,7 +101,7 @@ To push the complete multi-platform image, remove the --platform flag.
 	case !opts.all && reference.IsNameOnly(ref):
 		ref = reference.TagNameOnly(ref)
 		if tagged, ok := ref.(reference.Tagged); ok && !opts.quiet {
-			_, _ = fmt.Fprintf(dockerCli.Out(), "Using default tag: %s\n", tagged.Tag())
+			_, _ = fmt.Fprintln(dockerCli.Out(), "Using default tag:", tagged.Tag())
 		}
 	}
 

cli/command/image/remove.go

@@ -51,8 +51,8 @@ func newRemoveCommand(dockerCli command.Cli) *cobra.Command {
 	return &cmd
 }
 
-func runRemove(ctx context.Context, dockerCli command.Cli, opts removeOptions, images []string) error {
-	client := dockerCli.Client()
+func runRemove(ctx context.Context, dockerCLI command.Cli, opts removeOptions, images []string) error {
+	apiClient := dockerCLI.Client()
 
 	options := image.RemoveOptions{
 		Force:         opts.force,
@@ -62,7 +62,7 @@ func runRemove(ctx context.Context, dockerCli command.Cli, opts removeOptions, i
 	var errs []string
 	fatalErr := false
 	for _, img := range images {
-		dels, err := client.ImageRemove(ctx, img, options)
+		dels, err := apiClient.ImageRemove(ctx, img, options)
 		if err != nil {
 			if !errdefs.IsNotFound(err) {
 				fatalErr = true
@@ -71,9 +71,9 @@ func runRemove(ctx context.Context, dockerCli command.Cli, opts removeOptions, i
 		} else {
 			for _, del := range dels {
 				if del.Deleted != "" {
-					fmt.Fprintf(dockerCli.Out(), "Deleted: %s\n", del.Deleted)
+					_, _ = fmt.Fprintln(dockerCLI.Out(), "Deleted:", del.Deleted)
 				} else {
-					fmt.Fprintf(dockerCli.Out(), "Untagged: %s\n", del.Untagged)
+					_, _ = fmt.Fprintln(dockerCLI.Out(), "Untagged:", del.Untagged)
 				}
 			}
 		}
@@ -84,7 +84,7 @@ func runRemove(ctx context.Context, dockerCli command.Cli, opts removeOptions, i
 		if !opts.force || fatalErr {
 			return errors.New(msg)
 		}
-		fmt.Fprintln(dockerCli.Err(), msg)
+		_, _ = fmt.Fprintln(dockerCLI.Err(), msg)
 	}
 	return nil
 }