cli/command: add WithAPIClientOptions option

This option allows setting custom options to use when constructing
the API client.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/cli_options.go

@@ -104,6 +104,16 @@ func WithInitializeClient(makeClient func(*DockerCli) (client.APIClient, error))
 	}
 }
 
+// WithAPIClientOptions configures additional [client.Opt] to use when
+// initializing the API client. These options have no effect if a custom
+// client is set (through [WithAPIClient] or [WithInitializeClient]).
+func WithAPIClientOptions(c ...client.Opt) CLIOption {
+	return func(cli *DockerCli) error {
+		cli.clientOpts = append(cli.clientOpts, c...)
+		return nil
+	}
+}
+
 // envOverrideHTTPHeaders is the name of the environment-variable that can be
 // used to set custom HTTP headers to be sent by the client. This environment
 // variable is the equivalent to the HttpHeaders field in the configuration

cli/command/cli_test.go

@@ -393,3 +393,26 @@ func TestNewDockerCliWithCustomUserAgent(t *testing.T) {
 	assert.NilError(t, err)
 	assert.DeepEqual(t, received, "fake-agent/0.0.1")
 }
+
+func TestNewDockerCliWithAPIClientOptions(t *testing.T) {
+	var received string
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		received = r.UserAgent()
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer ts.Close()
+	host := strings.Replace(ts.URL, "http://", "tcp://", 1)
+	opts := &flags.ClientOptions{Hosts: []string{host}}
+
+	cli, err := NewDockerCli(
+		WithAPIClientOptions(client.WithUserAgent("fake-agent/0.0.1")),
+	)
+	assert.NilError(t, err)
+	cli.currentContext = DefaultContextName
+	cli.options = opts
+	cli.configFile = &configfile.ConfigFile{}
+
+	_, err = cli.Client().Ping(t.Context(), client.PingOptions{})
+	assert.NilError(t, err)
+	assert.DeepEqual(t, received, "fake-agent/0.0.1")
+}