bake: allow pattern matching for target names in --set

Although bake is for running multiple targets, --set required a single
target name for overriding a property. This change allows matching
multiple targets for overrides.

Signed-off-by: Tibor Vass <tibor@docker.com>

README.md

@@ -511,7 +511,7 @@ Options:
 |      --print             | Print the options without building
 |      --progress string   | Set type of progress output (auto, plain, tty). Use plain to show container output (default "auto")
 |      --pull              | Always attempt to pull a newer version of the image
-|      --set stringArray   | Override target value (eg: target.key=value)
+|      --set stringArray   | Override target value (eg: targetpattern.key=value)
 
 #### `-f, --file FILE`
 
@@ -554,14 +554,16 @@ Same as `build --progress`. Set type of progress output (auto, plain, tty). Use
 
 Same as `build --pull`.
 
-#### `--set target.key[.subkey]=value`
+#### `--set targetpattern.key[.subkey]=value`
 
-Override target configurations from command line.
+Override target configurations from command line. The pattern matching syntax is defined in https://golang.org/pkg/path/#Match.
 
 Example:
 ```
 docker buildx bake --set target.args.mybuildarg=value
 docker buildx bake --set target.platform=linux/arm64
+docker buildx bake --set foo*.args.mybuildarg=value	# overrides build arg for all targets starting with 'foo'
+docker buildx bake --set *.platform=linux/arm64		# overrides platform for all targets
 ```
 
 #### File definition

bake/bake.go

@@ -106,6 +106,26 @@ func mergeConfig(c1, c2 Config) Config {
 	return c1
 }
 
+func (c Config) expandTargets(pattern string) ([]string, error) {
+	if _, ok := c.Target[pattern]; ok {
+		return []string{pattern}, nil
+	}
+	var names []string
+	for name := range c.Target {
+		ok, err := path.Match(pattern, name)
+		if err != nil {
+			return nil, errors.Wrapf(err, "could not match targets with '%s'", pattern)
+		}
+		if ok {
+			names = append(names, name)
+		}
+	}
+	if len(names) == 0 {
+		return nil, errors.Errorf("could not find any target matching '%s'", pattern)
+	}
+	return names, nil
+}
+
 func (c Config) newOverrides(v []string) (map[string]Target, error) {
 	m := map[string]Target{}
 	for _, v := range v {
@@ -116,16 +136,19 @@ func (c Config) newOverrides(v []string) (map[string]Target, error) {
 			return nil, errors.Errorf("invalid override key %s, expected target.name", parts[0])
 		}
 
-		name := keys[0]
+		pattern := keys[0]
 		if len(parts) != 2 && keys[1] != "args" {
 			return nil, errors.Errorf("invalid override %s, expected target.name=value", v)
 		}
 
-		t := m[name]
-		if _, ok := c.Target[name]; !ok {
-			return nil, errors.Errorf("unknown target %s", name)
+		names, err := c.expandTargets(pattern)
+		if err != nil {
+			return nil, err
 		}
 
+		for _, name := range names {
+			t := m[name]
+
 			switch keys[1] {
 			case "context":
 				t.Context = &parts[1]
@@ -176,6 +199,7 @@ func (c Config) newOverrides(v []string) (map[string]Target, error) {
 			}
 			m[name] = t
 		}
+	}
 	return m, nil
 }
 

bake/bake_test.go

@@ -49,7 +49,7 @@ target "webapp" {
 	t.Run("InvalidTargetOverrides", func(t *testing.T) {
 		_, err := ReadTargets(ctx, []string{fp}, []string{"webapp"}, []string{"nosuchtarget.context=foo"})
 		require.NotNil(t, err)
-		require.Equal(t, err.Error(), "unknown target nosuchtarget")
+		require.Equal(t, err.Error(), "could not find any target matching 'nosuchtarget'")
 	})
 
 	t.Run("ArgsOverrides", func(t *testing.T) {

commands/bake.go

@@ -99,7 +99,7 @@ func bakeCmd(dockerCli command.Cli) *cobra.Command {
 
 	flags.StringArrayVarP(&options.files, "file", "f", []string{}, "Build definition file")
 	flags.BoolVar(&options.printOnly, "print", false, "Print the options without building")
-	flags.StringArrayVar(&options.overrides, "set", nil, "Override target value (eg: target.key=value)")
+	flags.StringArrayVar(&options.overrides, "set", nil, "Override target value (eg: targetpattern.key=value)")
 
 	commonFlags(&options.commonOptions, flags)