feat: add flag to print resolved config

.gitignore

@@ -1,5 +1,6 @@
 # Sometimes use these for testing
 .yamlfmt
+!integrationtest/**/.yamlfmt
 tmp
 
 # Goreleaser build folder

cmd/yamlfmt/flags.go

@@ -34,6 +34,7 @@ operation without performing it.`)
 	flagConf              *string = flag.String("conf", "", "Read yamlfmt config from this path")
 	flagGlobalConf        *bool   = flag.Bool("global_conf", false, fmt.Sprintf("Use global yamlfmt config from %s", globalConfFlagVar()))
 	flagDisableGlobalConf *bool   = flag.Bool("no_global_conf", false, fmt.Sprintf("Disabled usage of global yamlfmt config from %s", globalConfFlagVar()))
+	flagPrintConf         *bool   = flag.Bool("print_conf", false, "Print config")
 	flagDoublestar        *bool   = flag.Bool("dstar", false, "Use doublestar globs for include and exclude")
 	flagQuiet             *bool   = flag.Bool("quiet", false, "Print minimal output to stdout")
 	flagContinueOnError   *bool   = flag.Bool("continue_on_error", false, "Continue to format files that didn't fail instead of exiting with code 1.")
@@ -97,6 +98,9 @@ func getOperationFromFlag() yamlfmt.Operation {
 	if *flagDry {
 		return yamlfmt.OperationDry
 	}
+	if *flagPrintConf {
+		return yamlfmt.OperationPrintConfig
+	}
 	return yamlfmt.OperationFormat
 }
 

command/command.go

@@ -23,6 +23,9 @@ import (
 
 	"github.com/google/yamlfmt"
 	"github.com/google/yamlfmt/engine"
+	"github.com/mitchellh/mapstructure"
+
+	"github.com/braydonk/yaml"
 )
 
 type FormatterConfig struct {
@@ -159,6 +162,30 @@ func (c *Command) Run() error {
 			return err
 		}
 		fmt.Print(string(out))
+	case yamlfmt.OperationPrintConfig:
+		commandConfig := map[string]any{}
+		err = mapstructure.Decode(c.Config, &commandConfig)
+		if err != nil {
+			return err
+		}
+		delete(commandConfig, "formatter")
+		out, err := yaml.Marshal(commandConfig)
+		if err != nil {
+			return err
+		}
+		fmt.Print(string(out))
+
+		formatterConfigMap, err := formatter.ConfigMap()
+		if err != nil {
+			return err
+		}
+		out, err = yaml.Marshal(map[string]any{
+			"formatter": formatterConfigMap,
+		})
+		if err != nil {
+			return err
+		}
+		fmt.Print(string(out))
 	}
 
 	return nil

docs/command-usage.md

@@ -59,14 +59,15 @@ All flags must be specified **before** any path arguments.
 
 These flags adjust the command's mode of operation. All of these flags are booleans.
 
-| Name          | Flag       | Example                     | Description                                               |
-| :------------ | :--------- | :-------------------------- | :-------------------------------------------------------- |
-| Help          | `-help`    | `yamlfmt -help`             | Print the command usage information.                      |
-| Print Version | `-version` | `yamlfmt -version`          | Print the yamlfmt version.                                |
-| Dry Run       | `-dry`     | `yamlfmt -dry .`            | Use [Dry Run](#dry-run) mode                              |
-| Lint          | `-lint`    | `yamlfmt -lint .`           | Use [Lint](#lint) mode                                    |
-| Quiet Mode    | `-quiet`   | `yamlfmt -dry -quiet .`     | Use quiet mode. Only has effect in Dry Run or Lint modes. |
-| Read Stdin    | `-in`      | `cat x.yaml \| yamlfmt -in` | Read input from stdin and output result to stdout.        |
+| Name          | Flag          | Example                     | Description                                               |
+| :------------ | :------------ | :-------------------------- | :-------------------------------------------------------- |
+| Help          | `-help`       | `yamlfmt -help`             | Print the command usage information.                      |
+| Print Version | `-version`    | `yamlfmt -version`          | Print the yamlfmt version.                                |
+| Print Config  | `-print_conf` | `yamlfmt -print_conf`       | Print the merged configuration to use.                    |
+| Dry Run       | `-dry`        | `yamlfmt -dry .`            | Use [Dry Run](#dry-run) mode                              |
+| Lint          | `-lint`       | `yamlfmt -lint .`           | Use [Lint](#lint) mode                                    |
+| Quiet Mode    | `-quiet`      | `yamlfmt -dry -quiet .`     | Use quiet mode. Only has effect in Dry Run or Lint modes. |
+| Read Stdin    | `-in`         | `cat x.yaml \| yamlfmt -in` | Read input from stdin and output result to stdout.        |
 
 ### Configuration Flags
 

docs/config-file.md

@@ -26,6 +26,8 @@ If the flag `-global_conf` is passed, all other steps will be circumvented and t
 
 In the `-conf` flag, the config file can be named anything. As long as it's valid yaml, yamlfmt will read it as a config file. This can be useful for applying unique configs to different directories in a project. The automatic discovery paths do need to use one of the known names.
 
+In the `-print_conf` flag, merged config values will be printed.
+
 ## Command
 
 The command package defines the main command engine that `cmd/yamlfmt` uses. It uses the top level configuration that any run of the yamlfmt command will use.

engine.go

@@ -29,6 +29,7 @@ const (
 	OperationLint
 	OperationDry
 	OperationStdin
+	OperationPrintConfig
 )
 
 type Engine interface {

formatter.go

@@ -19,6 +19,7 @@ import "fmt"
 type Formatter interface {
 	Type() string
 	Format(yamlContent []byte) ([]byte, error)
+	ConfigMap() (map[string]any, error)
 }
 
 type Factory interface {

formatters/basic/formatter.go

@@ -21,6 +21,7 @@ import (
 
 	"github.com/braydonk/yaml"
 	"github.com/google/yamlfmt"
+	"github.com/mitchellh/mapstructure"
 )
 
 const BasicFormatterType string = "basic"
@@ -113,3 +114,13 @@ func (f *BasicFormatter) getNewEncoder(buf *bytes.Buffer) *yaml.Encoder {
 
 	return e
 }
+
+func (f *BasicFormatter) ConfigMap() (map[string]any, error) {
+	configMap := map[string]any{}
+	err := mapstructure.Decode(f.Config, &configMap)
+	if err != nil {
+		return nil, err
+	}
+	configMap["type"] = BasicFormatterType
+	return configMap, err
+}

integrationtest/command/command_test.go

@@ -100,3 +100,26 @@ func TestDryQuiet(t *testing.T) {
 		Update:  *updateFlag,
 	}.Run(t)
 }
+
+func TestPrintConfFlags(t *testing.T) {
+	TestCase{
+		Dir:     "print_conf_flags",
+		Command: yamlfmtWithArgs("-print_conf -continue_on_error=true -formatter retain_line_breaks=true"),
+		Update:  *updateFlag,
+	}.Run(t)
+}
+
+func TestPrintConfFile(t *testing.T) {
+	TestCase{
+		Dir:     "print_conf_file",
+		Command: yamlfmtWithArgs("-print_conf"),
+		Update:  *updateFlag,
+	}.Run(t)
+}
+func TestPrintConfFlagsAndFile(t *testing.T) {
+	TestCase{
+		Dir:     "print_conf_flags_and_file",
+		Command: yamlfmtWithArgs("-print_conf -continue_on_error=true -formatter retain_line_breaks=true"),
+		Update:  *updateFlag,
+	}.Run(t)
+}

integrationtest/command/testdata/print_conf_file/after/.yamlfmt

@@ -0,0 +1,11 @@
+continue_on_error: false
+doublestar: true
+exclude:
+  - "**/templates/*.yaml"
+gitignore_excludes: false
+gitignore_path: .my_gitignore
+line_ending: crlf
+formatter:
+    type: basic
+    retain_line_breaks_single: true
+    include_document_start: true

integrationtest/command/testdata/print_conf_file/after/a.yaml

@@ -0,0 +1,2 @@
+a:
+ b: 1

integrationtest/command/testdata/print_conf_file/before/.yamlfmt

@@ -0,0 +1,11 @@
+continue_on_error: false
+doublestar: true
+exclude:
+  - "**/templates/*.yaml"
+gitignore_excludes: false
+gitignore_path: .my_gitignore
+line_ending: crlf
+formatter:
+    type: basic
+    retain_line_breaks_single: true
+    include_document_start: true

integrationtest/command/testdata/print_conf_file/before/a.yaml

@@ -0,0 +1,2 @@
+a:
+ b: 1

integrationtest/command/testdata/print_conf_file/stdout/stdout.txt

@@ -0,0 +1,26 @@
+continue_on_error: false
+doublestar: true
+exclude:
+    - '**/templates/*.yaml'
+extensions:
+    - yaml
+    - yml
+gitignore_excludes: false
+gitignore_path: .my_gitignore
+include: []
+line_ending: crlf
+output_format: default
+regex_exclude: []
+formatter:
+    disallow_anchors: false
+    drop_merge_tag: false
+    include_document_start: true
+    indent: 2
+    indentless_arrays: false
+    line_ending: crlf
+    max_line_length: 0
+    pad_line_comments: 1
+    retain_line_breaks: false
+    retain_line_breaks_single: true
+    scan_folded_as_literal: false
+    type: basic

integrationtest/command/testdata/print_conf_flags/after/a.yaml

@@ -0,0 +1,2 @@
+a:
+ b: 1

integrationtest/command/testdata/print_conf_flags/before/a.yaml

@@ -0,0 +1,2 @@
+a:
+ b: 1

integrationtest/command/testdata/print_conf_flags/stdout/stdout.txt

@@ -0,0 +1,25 @@
+continue_on_error: true
+doublestar: false
+exclude: []
+extensions:
+    - yaml
+    - yml
+gitignore_excludes: false
+gitignore_path: .gitignore
+include: []
+line_ending: lf
+output_format: default
+regex_exclude: []
+formatter:
+    disallow_anchors: false
+    drop_merge_tag: false
+    include_document_start: false
+    indent: 2
+    indentless_arrays: false
+    line_ending: lf
+    max_line_length: 0
+    pad_line_comments: 1
+    retain_line_breaks: true
+    retain_line_breaks_single: false
+    scan_folded_as_literal: false
+    type: basic

integrationtest/command/testdata/print_conf_flags_and_file/after/.yamlfmt

@@ -0,0 +1,11 @@
+continue_on_error: false
+doublestar: true
+exclude:
+  - "**/templates/*.yaml"
+gitignore_excludes: false
+gitignore_path: .my_gitignore
+line_ending: crlf
+formatter:
+    type: basic
+    retain_line_breaks_single: true
+    include_document_start: true

integrationtest/command/testdata/print_conf_flags_and_file/after/a.yaml

@@ -0,0 +1,2 @@
+a:
+ b: 1

integrationtest/command/testdata/print_conf_flags_and_file/before/.yamlfmt

@@ -0,0 +1,11 @@
+continue_on_error: false
+doublestar: true
+exclude:
+  - "**/templates/*.yaml"
+gitignore_excludes: false
+gitignore_path: .my_gitignore
+line_ending: crlf
+formatter:
+    type: basic
+    retain_line_breaks_single: true
+    include_document_start: true

integrationtest/command/testdata/print_conf_flags_and_file/before/a.yaml

@@ -0,0 +1,2 @@
+a:
+ b: 1

integrationtest/command/testdata/print_conf_flags_and_file/stdout/stdout.txt

@@ -0,0 +1,26 @@
+continue_on_error: true
+doublestar: true
+exclude:
+    - '**/templates/*.yaml'
+extensions:
+    - yaml
+    - yml
+gitignore_excludes: false
+gitignore_path: .my_gitignore
+include: []
+line_ending: crlf
+output_format: default
+regex_exclude: []
+formatter:
+    disallow_anchors: false
+    drop_merge_tag: false
+    include_document_start: true
+    indent: 2
+    indentless_arrays: false
+    line_ending: crlf
+    max_line_length: 0
+    pad_line_comments: 1
+    retain_line_breaks: true
+    retain_line_breaks_single: true
+    scan_folded_as_literal: false
+    type: basic