Refactor content_trust cli/flags handling

Remove the global variable used. Allows easier unit testing.

Signed-off-by: Vincent Demeester <vincent@sbr.pm>

cmd/docker/docker.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"os"
+	"strconv"
 	"strings"
 
 	"github.com/docker/cli/cli"
@@ -155,7 +156,7 @@ func main() {
 	stdin, stdout, stderr := term.StdStreams()
 	logrus.SetOutput(stderr)
 
-	dockerCli := command.NewDockerCli(stdin, stdout, stderr)
+	dockerCli := command.NewDockerCli(stdin, stdout, stderr, isContentTrustEnabled())
 	cmd := newDockerCommand(dockerCli)
 
 	if err := cmd.Execute(); err != nil {
@@ -175,6 +176,16 @@ func main() {
 	}
 }
 
+func isContentTrustEnabled() bool {
+	if e := os.Getenv("DOCKER_CONTENT_TRUST"); e != "" {
+		if t, err := strconv.ParseBool(e); t || err != nil {
+			// treat any other value as true
+			return true
+		}
+	}
+	return false
+}
+
 func showVersion() {
 	fmt.Printf("Docker version %s, build %s\n", cli.Version, cli.GitCommit)
 }

cmd/docker/docker_test.go

@@ -26,7 +26,7 @@ func TestClientDebugEnabled(t *testing.T) {
 
 func TestExitStatusForInvalidSubcommandWithHelpFlag(t *testing.T) {
 	discard := ioutil.Discard
-	cmd := newDockerCommand(command.NewDockerCli(os.Stdin, discard, discard))
+	cmd := newDockerCommand(command.NewDockerCli(os.Stdin, discard, discard, false))
 	cmd.SetArgs([]string{"help", "invalid"})
 	err := cmd.Execute()
 	assert.Error(t, err, "unknown help topic: invalid")