skeleton to adopt Cobra completion v2

Signed-off-by: Nicolas De Loof <nicolas.deloof@gmail.com>

cli/context/store/store.go

@@ -119,6 +119,19 @@ func (s *store) List() ([]Metadata, error) {
 	return s.meta.list()
 }
 
+// Names return Metadata names for a Lister
+func Names(s Lister) ([]string, error) {
+	list, err := s.List()
+	if err != nil {
+		return nil, err
+	}
+	var names []string
+	for _, item := range list {
+		names = append(names, item.Name)
+	}
+	return names, nil
+}
+
 func (s *store) CreateOrUpdate(meta Metadata) error {
 	return s.meta.createOrUpdate(meta)
 }

cmd/docker/completions.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"strings"
+
+	"github.com/docker/cli/cli/command"
+	"github.com/docker/cli/cli/context/store"
+	"github.com/spf13/cobra"
+)
+
+func registerCompletionFuncForGlobalFlags(dockerCli *command.DockerCli, cmd *cobra.Command) {
+	cmd.RegisterFlagCompletionFunc(
+		"context",
+		func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+			names, err := store.Names(dockerCli.ContextStore())
+			if err != nil {
+				return nil, cobra.ShellCompDirectiveError
+			}
+
+			return filterForCompletion(names, toComplete), cobra.ShellCompDirectiveDefault
+		},
+	)
+	cmd.RegisterFlagCompletionFunc(
+		"log-level",
+		func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+			values := []string{"debug", "info", "warn", "error", "fatal"}
+			return filterForCompletion(values, toComplete), cobra.ShellCompDirectiveDefault
+		},
+	)
+}
+
+func filterForCompletion(values []string, toComplete string) []string {
+	var offer []string
+	for _, v := range values {
+		if strings.HasPrefix(v, toComplete) {
+			offer = append(offer, v)
+		}
+	}
+	return offer
+}

cmd/docker/docker.go

@@ -47,8 +47,13 @@ func newDockerCommand(dockerCli *command.DockerCli) *cli.TopLevelCommand {
 		},
 		Version:               fmt.Sprintf("%s, build %s", version.Version, version.GitCommit),
 		DisableFlagsInUseLine: true,
+		CompletionOptions: cobra.CompletionOptions{
+			DisableDefaultCmd: false,
+			HiddenDefaultCmd:  true,
+		},
 	}
 	opts, flags, helpCmd = cli.SetupRootCommand(cmd)
+	registerCompletionFuncForGlobalFlags(dockerCli, cmd)
 	flags.BoolP("version", "v", false, "Print version information and quit")
 
 	setFlagErrorFunc(dockerCli, cmd)

vendor.mod

@@ -21,12 +21,10 @@ require (
 	github.com/docker/swarmkit v1.12.1-0.20210726173615-3629f50980f6
 	github.com/fvbommel/sortorder v1.0.2
 	github.com/gogo/protobuf v1.3.2
-	github.com/golang/protobuf v1.5.2 // indirect
-	github.com/google/go-cmp v0.5.5
+	github.com/google/go-cmp v0.5.6
 	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510
 	github.com/imdario/mergo v0.3.12
-	github.com/json-iterator/go v1.1.10 // indirect
-	github.com/mitchellh/mapstructure v1.3.2
+	github.com/mitchellh/mapstructure v1.4.3
 	github.com/moby/buildkit v0.8.2-0.20210615162540-9f254e18360a
 	github.com/moby/sys/signal v0.6.0
 	github.com/moby/term v0.0.0-20210619224110-3f7ff695adc6
@@ -35,17 +33,15 @@ require (
 	github.com/opencontainers/image-spec v1.0.1
 	github.com/pkg/errors v0.9.1
 	github.com/sirupsen/logrus v1.8.1
-	github.com/spf13/cobra v1.1.3
+	github.com/spf13/cobra v1.3.0
 	github.com/spf13/pflag v1.0.5
 	github.com/theupdateframework/notary v0.7.1-0.20210315103452-bf96a202a09a
 	github.com/tonistiigi/go-rosetta v0.0.0-20200727161949-f79598599c5d
 	github.com/xeipuuv/gojsonpointer v0.0.0-20190905194746-02993c407bfb // indirect
 	github.com/xeipuuv/gojsonschema v1.2.0
-	golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d // indirect
-	golang.org/x/sys v0.0.0-20211025201205-69cdffdb9359
+	golang.org/x/sys v0.0.0-20211205182925-97ca703d548d
 	golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1
-	golang.org/x/text v0.3.4
-	google.golang.org/grpc v1.38.0 // indirect
+	golang.org/x/text v0.3.7
 	gopkg.in/yaml.v2 v2.4.0
 	gotest.tools/v3 v3.0.3
 	k8s.io/api v0.20.6